# 1" Bore x 1" Stroke Vertical i.c. Engine



## Brian Rupnow (Jan 26, 2021)

Hi Everyone---Hope your new year is going well, so far. I fell on the ice in my driveway just after Christmas and hurt my back. Between the pain from that, and my arthritis (which is exceptionally bad this year), I've had a very quiet January. Finally, today, out of boredom I sat down at my computer and started importing files from previous engines to see what would be involved in another i.c. engine. I have never built an engine before with a vertically split crank-case, so after looking at some really lovely examples on the forums, I've started putting things together on cad. I enjoy a quiet day designing, and this is what has turned up so far. Nothing really new or exciting here, but I like to see an engine coming together. I have no cnc here, just manual machinery, so that's what my engine will be based on, build-wise.---Brian


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## johnmcc69 (Jan 26, 2021)

Looking forward to seeing it come together Brian!

 John


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## ShopShoe (Jan 27, 2021)

Brian,

So sorry to hear about your back. I hope it gets better.

Meanwhile, I'll be following your new design.

--ShopShoe


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## Brian Rupnow (Jan 27, 2021)

I spent this morning sussing out the cylinder head and the valve train. It looks good to me right now, so I'll go eat some lunch and then see if it still pleases me when I come back this afternoon.


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## Eccentric (Jan 27, 2021)

I am liking it Brian.  I like the parallel cam shaft/crankshaft layout.  Will you use aluminum cyclinder and head with a cast iron liner? Or solid cast iron cylinder?  Is the stroke also going to be an 1"?, will this be on the higher compression side then?  Sorry about your slip, and I understand about the arthritis, my fingers really flare up when it gets cold.


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## petertha (Jan 27, 2021)

One suggestion I would make is: mill a flat on the head where the inlet/exhaust ports enter so that your pipe can be flanged & bolted to the head. My radial has counterbores with internal threads. They require threaded nuts, up-turned or trumpeted ends on the tubing & some kind of internal seal ring or washer (capable of temp on exhaust). And there typically isn't a lot of meat in the head for internal threads anyways. A flanged pipe & gasket eliminates a lot of these fiddle-fart issues.


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## Brian Rupnow (Jan 27, 2021)

Most of the work today was centered around the cylinder head. The carb shown is a Traxxas 4033, and the valves are 1/8" stem diameter with a 3/8" head. The exhaust is identical to what I used on the vertical hit and miss engine last year, and I'm thinking I may pack it with steel wool to see what effect that has on the sound.


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## Brian Rupnow (Jan 27, 2021)

My life is a lot simpler when I make the cylinder from solid grey cast iron. I could do an aluminum cylinder with an cast iron liner, but all that does is complicate things, and the heat dissipation is never as good. Petertha--I've never had an issue with threaded ports in the cylinder head for the carb adapter and exhaust to screw into. I could make flanged connections as you suggest, but that just makes more work. I find that a dab of 638 Loctite keeps things from coming unscrewed, but it can still be disassembled with  wrench if I need to.


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## Brian Rupnow (Jan 27, 2021)

This engine will have the timing gears on the outside of the case. They will get their own polished brass??? cover. I haven't mounted the ignition points yet, but will probably set them up to be between the crankcase and the flywheel.


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## Brian Rupnow (Jan 27, 2021)

That's enough silliness for one day. Tomorrow I'll figure out a mounting plate for the ignition points and a gas tank.


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## awake (Jan 28, 2021)

Looking good, Brian. Are you planning on using a wet sump / splash lubrication? I guess you'll need a vent for the crankcase - ? (I am asking out of ignorance, not as a veiled suggestion!)


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## Brian Rupnow (Jan 28, 2021)

Yes, it will be a wet sump. The design is not complete yet.


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## Brian Rupnow (Jan 28, 2021)

So, here we have it at 99% designed. An interesting little engine, with maybe a few shiny brass (gold??) parts just to set off the iron and aluminum cylinder and crank case.  The crankshaft and the camshaft ride on sealed ball bearings, and the cams are inside the crankcase to guarantee splash oiling from the wet sump. For a little bit of added "pretty", I've designed a rather swoopy gas tank support.---After designing and building about a dozen of this type of engine, everything begins to look the same. I will run a Viton piston ring on this engine. Any comments are welcome.


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## Brian Rupnow (Jan 28, 2021)

In this view of the engine, I have hidden the flywheel so you can see the plate which the ignition points are attached to. That plate has a split in it and rotates on a boss attached to the crank case. By unscrewing the blue handle the plate can be turned clockwise or counterclockwise, giving the ability to dynamically advance or retard the ignition while the engine is running. the drawing shows overall sizes.


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## CFLBob (Jan 28, 2021)

At last an engine where I can figure out the cubic inches of displacement in my head! 

Are you conceptually done?  There's no RPM control here.  I'm leaning toward my next build being a hit and miss., as I find that interesting. 

BTW, good to hear you're recovering from the fall.  I can joke about it, but falls on ice can be as serious as it gets.


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## Jasonb (Jan 28, 2021)

The Traxxas carb Brian shows has a throttle on it to adjust speed, timing will also have a big effect on rpm.

Looks like Brian has drawn heavily on the 1936 Midget design for this one and that actually just had a straight through venturi on it so all out or nothing. I made a carb for mine with a throttle barrel.


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## Brian Rupnow (Jan 28, 2021)

Jason---You're right. The 1936 Midget was my inspiration for this engine. Bob, I highly recommend the Kerzel horizontal hit and miss. It is a great little engine, and uses a lot of the skills you have honed on the Webster.  A word of warning though---don't use a Viton ring on the Kerzel. If you do you'll get great compression but really poor coasting cycles because of the drag.





						Brian Builds the Kerzel Hit and Miss I.C.
					

Okay Guys and Girls---A bit of a change in the game plan. I was going to build the Upshore "Farm Boy" engine, but I want this engine to be water cooled, and I found a set of free plans with what I think is a nicer cylinder design at http://www.floridaame.org/GalleryPages/g1h0106.htm This is not...




					www.homemodelenginemachinist.com


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## Ghosty (Jan 28, 2021)

Brian,
This one looks good, will be watching this.
Andrew


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## Jasonb (Jan 28, 2021)

Brian, are you going to be using a lost spark? I see you have your points on the crankshaft so will be getting a spark every turn of the crank rather than every other turn that is more usual for a 4-stroke.


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## Brian Rupnow (Jan 28, 2021)

Jason---I always mount the points to run off the crankshaft, so yes, it is a wasted spark system. Doing it this way gives you a lot more room to mount the points.


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## Brian Rupnow (Jan 28, 2021)

So, there we have it. The design is essentially finished. My computer tells me that there are a total of 74 individual components, not counting fasteners. The two crank-case halves are designed to be cut from 3" x 1" aluminum flat bar. The base can be cut from a piece of 2" x 1" aluminum flat bar. I haven't included the poppet valve which screws into the crankcase to keep the crank-case in a semi vacuum condition (to avoid oil leaks around the bearings), because I'm not really sure that I need it. If I find out "after the fact" that I do need it, it can always be added later. The oil filler tube and cap have been added, as well as a drain plug in the very bottom. An "oil level check" hole and plug have been added to the side of the crankcase.  You can see it just to the left of the outer gear case. You take out the plug and add oil in the filler tube until it starts to run out that hole. That hole is positioned so that when oil starts to run out of it, you know the oil level is correct. All of the tapped holes and clearance holes for fasteners have been added. The only thing I haven't totally decided on is how to attach the outer gear case to the crank case. If I make it from brass $$$, I can silver solder a couple of mounting tabs to it. If I cheap out and make it from aluminum, then it becomes a different story because I can't weld aluminum.


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## awake (Jan 29, 2021)

Brian, one possible concern that occurred to me in the previous set of renderings - it looks like the fuel line from the tank to the carb may wind up rather close to the flywheel - ?


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## Brian Rupnow (Jan 29, 2021)

I sent out a request for pricing this morning for material to make the two crank case pieces and the base from aluminum, enough brass to make the gas tank support, the rocker arm tower and the gearcase, and a piece of grey cast iron to make the cylinder from. I have scraps of material laying around here to make almost all of the remaining pieces. I have a section of heavy wall pipe sufficient to make the flywheel from, with a machined aluminum center.


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## Brian Rupnow (Jan 29, 2021)

Awake--Many of the models used in this engine were imported from other older machine files. It just so happened that when I imported the gas tank assembly, the discharge spigot was as you see it.--Same as the inlet port on the carburetor. In reality I will be changing their position a bit to ensure that the fuel line is well clear of the flywheel.


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## Brian Rupnow (Jan 29, 2021)

The aluminum bar for the crankcase and base was the easy part.---$30.


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## awake (Jan 29, 2021)

Brian Rupnow said:


> Awake--Many of the models used in this engine were imported from other older machine files. It just so happened that when I imported the gas tank assembly, the discharge spigot was as you see it.--Same as the inlet port on the carburetor. In reality I will be changing their position a bit to ensure that the fuel line is well clear of the flywheel.



I wondered if that might be the case. Looking forward to seeing this take shape!


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## Brian Rupnow (Jan 29, 2021)

Hah!!!--Sometimes a nights sleep helps out your thinking process!!! I can attach the gear case with two #10 shcs. I wanted to do that yesterday, but  I was thinking that the bolts would break through the side of the crankcase in the thin area behind the ball bearing. This morning I see that that is not so, there will be lots of "meat" for the screw threads which hold the gear cover up against the side of the crankcase.


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## Eccentric (Jan 29, 2021)

Brian, don't put steel wool in your muffler, I love the sound of these engines un-muffled.   I make it a practice not to count the number of parts I need to make, that way I am always "just a couple of parts away from being done."  Looking good, you don't mess around when puttin an engine together, I fiddle with one part longer than it takes you to crank out a whole new design.


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## Jasonb (Jan 29, 2021)

I'm still trying to work out where all those 74 parts are, mine only came to 58 excluding fixings and 8 of those were for the carb

Another vote for an open exhaust stub pipe.


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## Brian Rupnow (Jan 29, 2021)

The two crank-case halves will be right and left hand on a lot of the major features, but there will be a number of features which apply only to one side or the other. The first thing to do before I start cutting and carving is to drill and ream each half for a 3/16" diameter locating dowel. These holes will have virtually zero clearance between them and the dowels so that I don't end up with two crank-cases that don't match up in some of the critical areas. The dowel holes are put into the crank-case halves in areas where they don't interfere with anything else.


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## Brian Rupnow (Jan 29, 2021)

Jason--I do trust my computer on the quantity of parts, but it looks at every individual part. For instance, I have the carburetor designed as a part file, so it only gets counted as one part. The gas tank assembly is counted as 10 or 12 individual parts, and if there are three parts that are identical, the computer counts each one of them.


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## Larry G. (Jan 29, 2021)

Brian Rupnow said:


> So, there we have it. The design is essentially finished. My computer tells me that there are a total of 74 individual components, not counting fasteners. The two crank-case halves are designed to be cut from 3" x 1" aluminum flat bar. The base can be cut from a piece of 2" x 1" aluminum flat bar. I haven't included the poppet valve which screws into the crankcase to keep the crank-case in a semi vacuum condition (to avoid oil leaks around the bearings), because I'm not really sure that I need it. If I find out "after the fact" that I do need it, it can always be added later. The oil filler tube and cap have been added, as well as a drain plug in the very bottom. An "oil level check" hole and plug have been added to the side of the crankcase.  You can see it just to the left of the outer gear case. You take out the plug and add oil in the filler tube until it starts to run out that hole. That hole is positioned so that when oil starts to run out of it, you know the oil level is correct. All of the tapped holes and clearance holes for fasteners have been added. The only thing I haven't totally decided on is how to attach the outer gear case to the crank case. If I make it from brass $$$, I can silver solder a couple of mounting tabs to it. If I cheap out and make it from aluminum, then it becomes a different story because I can't weld aluminum.


Make the flat gear cover out of thin (cheap) brass sheet and the thicker curved portions out pf aluminum?


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## Brian Rupnow (Jan 29, 2021)

That doesn't work so well as there is no good way to attach them together.


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## Brian Rupnow (Jan 29, 2021)

I picked up my aluminum for the crank case and base today after lunch, and spent a quiet afternoon detailing. When right and left hand parts are simple, you can get away with one drawing, specifying "One as shown and one opposite hand". When they get fairly complicated there is much less chance of something getting machined wrong if two drawings are made, one of the right hand part and one of the left hand part.


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## werowance (Jan 29, 2021)

Brian,  i just saw the start of your build and am posting to subscribe.

one thing i thought might help is on the cylinder,  the upshur solders the cylinder to the square mounting plate and works well.  could save some cutting and stock waste.  but im watching to see how you do it.  

also sorry to hear about your fall,  i stepped out the door the other morning and slipped,  slid across the concrete porch and down 4 steps then halfway across the little stepping stones before i stopped.  i got lucky,  nothing broken.  that black ice will get you.


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## Larry G. (Jan 29, 2021)

Brian Rupnow said:


> That doesn't work so well as there is no good way to attach them together.


Some people like the look of old time riveted pressure vessels.  Lots of 4-40 button head SHCS around the perimeter?    Black steel alloy or silver SS...


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## Jasonb (Jan 30, 2021)

That's a big crankcase Brian, have you just made it to the original sizes and are going to put a small 1" bore cylinder on it as it looks to measure up more to suit the originals 1.25" bore, and you also have the large 4.5" flywheel. 

Although slightly smaller than your 1" my 24mm bore version has a crankcase 62mm tall and 80mm flywheel

You could solder up the gear cover from brass, just a flat plate with a rebate machined around it and then bend some thing strip to form the edge and solder together. If you leave the overall size of the plate larger than needed it can be filed flush to the sides after soldering.


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## Brian Rupnow (Jan 30, 2021)

This morning the 3" x 1" aluminum bar was cut to 2 pieces the correct overall length and then both pieces were drilled thru and reamed for 3/16"  alignment rods loctited into the holes to keep the plates perfectly aligned. The two holes for the shafts passing thru were both drilled and reamed to the shaft size (They will be opened up for clearance at a later stage of machining). The five counterbored holes were first drilled completely thru with the correct tap size for #10 thread, then opened up as #10 clearance holes 1" deep thru the first plate, then counterbored. Next step will be to tap the five holes for #10 thread and profile the outer edge of the two plates (while still pinned together).


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## Brian Rupnow (Jan 30, 2021)

So---the "easy" part is done. The sides have all been profiled and the holes drilled, tapped and counterbored. I have some more profiling to do on each side of the crankcase, and then the exciting part starts---machining the inside cavities. The reason that I drilled and reamed the shaft holes "on size" is to aid me when setting up in the four jaw chuck to machine the cavities. I just think it will be easier to indicate off a shaft stuck in the reamed hole than trying to pick up center from the reamed holes.


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## Brian Rupnow (Jan 30, 2021)

Using my time honored tradition of "make it up as I go along"---In order to turn that boss on the side of the crank-case, it's a trick. What I really have to do is machine all the material away except the boss. To do that, I have to be able to hold the crankcase in my rotary table. I need something to "grab onto" with the 3 jaw chuck which is permanently mounted to the rotary table. I can mill 90% of the material away by just mounting the crankcase in my swivel based vice. However, the corners need to be milled away, and for that I need the rotary table. So---I've loctited a piece of 3/8" shaft into the 3/8" bore in the crankcase, letting it stick out about 1" on each side. That will let me do the radius on both sides on the big end. Then I will press that shaft out and loctite a 5/16" shaft into the other end to allow me to radius the other end.  Not a really good method for production, but should work fine on a "one off".


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## Brian Rupnow (Jan 30, 2021)

Today I determined that if I swapped positions of the carburetor and the exhaust, that would keep my gas line away from the flywheel and give me room to mount a small, belt driven fan between the flywheel and exhaust. Similar to an earlier vertical i.c. that I designed and built a few years ago, the belt would be an o-ring driven by the flywheel. I haven't shown it here, but may have time tomorrow to do some more on the design.


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## Steamchick (Jan 31, 2021)

Brian Rupnow said:


> I picked up my aluminum for the crank case and base today after lunch, and spent a quiet afternoon detailing. When right and left hand parts are simple, you can get away with one drawing, specifying "One as shown and one opposite hand". When they get fairly complicated there is much less chance of something getting machined wrong if two drawings are made, one of the right hand part and one of the left hand part.


Hi Brian, In case I missed it. Will you be selling sets of plans after the "little beauty" is finished? - I guess you may do some odd mods as you make... so don't expect all drawings to be finalised until then. But I like the simplicicity of this engine - it looks as they did when I was a lad! I'd be proud to make this one!
K2


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## Brian Rupnow (Jan 31, 2021)

Here we are at boss machining stage-1. All of the material that can be removed has been removed using conventional "in the vice" machining. Now it's time to step over to the rotary table and round the corners on the large end boss on both sides.


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## Brian Rupnow (Jan 31, 2021)

Well, I must say---that worked out even better than I thought it was going to do. The radius on both sides only took a few minutes. Now I'll press that shaft out and loctite a shaft in the other hole so I can finish the machining at that end.


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## Brian Rupnow (Jan 31, 2021)

Steamchick--yes, after the project is completed and all of the drawings updated to reflect what actually got built, I sell the plan sets for $25 Canadian funds.


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## Basil (Jan 31, 2021)

Can't wait to see it come together. Probably my next build.


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## oldengineguy (Jan 31, 2021)

Brian  Add me to the list of people who will buy plans when available.  Looks GREAT!   Colin


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## Brian Rupnow (Jan 31, 2021)

I can't believe how well this turned out. Machining these bosses qualifies as "something I hadn't done before". Tomorrow there are about 13 or 15 holes to be added (most of them tapped). I haven't got the ball bearings yet, but they are supposed to arrive tomorrow. I don't want to separate the pieces, get all set up to bore the cavities in my 4 jaw chuck lathe, and then not have the bearings. Since there are major cavities to be bored in both halves, I have to try and decide if I should drill and tap all the holes I can now, and put up with interrupted cuts while I'm boring the major cavities, or wait until after I have bored the major cavities to put in all the threaded holes. Probably the second option makes more sense, and I do have other parts I can be working on while I wait for the bearings.


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## Brian Rupnow (Feb 1, 2021)

I have enough aluminum plate and steel ring to make a two piece flywheel. Of course, this lets me fool around a bit with the design. I kind of like this. The outer steel rim would be attached to the aluminum center with steel pins which extend thru the steel flywheel into the aluminum spokes. The heads of the pins might be visible where they extend thru the outside diameter of the flywheel, then get machined flush or I might even make them from brass and let them be a design feature.


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## Jasonb (Feb 1, 2021)

Steamchick, if you want one that looks like you remember as a lad the original drawings that this is heavily based on can be found on the net, I assume it's you on the left!





It was originally in Popular Mechanics with drawings for making your own castings and the machining drawings in a second issue but easy enough to cut from solid. If you search "midget gas engine 1936" or 1936 Midget Engine"  you can find a few and links to the drawings. Brian has included most of the modifications to the fairly basic design that I made when building my version of it though I went with the more traditional crankcase shape, starting cord pully etc.


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## Brian Rupnow (Feb 1, 2021)

Now I need some help. I am searching for a 4 or 5 blade plastic fan or propeller that is 1.375" to 1.5" outside diameter.  I'm not too concerned about the shaft size because I can make my shaft to suit. I would like to source it in North America, I don't care where it is made. I spent half an hour Googling nd couldn't find one. I want to use it as a cooling fan on this engine and I don't have room for anything larger in diameter. Does anyone have a source or a link?---Brian


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## awake (Feb 1, 2021)

Brian, I made a design for 3d printing a fan with no supports required. I plan to use the resulting fan on the Tower Engine ... that build that has been languishing for the lo these many months, but which I WILL get back to, hopefully sooner rather than later. What I don't know is whether the fan will stand up to the heat, even printed from a higher heat material like PETG. I'm hoping the air flow will keep the fan cool enough, but that remains to be seen.

I'm trying to find the file - apparently it is not where I thought it was. Hopefully I didn't accidentally delete it! (If so, I'll definitely recreate it). But in any case, if you are interested, I'll be happy to send it to you.


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## Jasonb (Feb 1, 2021)

Cut from thin sheet twist each blade to give it some set and soft solder or loctite to a hub. Does not have to be anything fancy you can just mill some radial slots and make the outside round on the rotary table. At least that way anyone buying the drawings can do the same where ever they are in the world. Did similar for the Thompson and RMC


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## Brian Rupnow (Feb 1, 2021)

Thanks Jason--I know that I can make a fan. If I can buy a manufactured plastic fan finished and ready to go for the right price, I would prefer to do that.---Brian


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## werowance (Feb 1, 2021)

i can 3d print you one if you like  send me a dfx file of the design and ill print it out in black pla for you


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## CFLBob (Feb 1, 2021)

40 mm, about 1-5/8, and 30 mm, about 1-1/8, fans are common in electronics, but are run on DC voltage.  Do you want to dismantle it and just use the fan blades?  It will be smaller than that because the named size is the case size.

40mm fan | Newegg.com 









						30mm fan | Newegg.com
					

Search Newegg.com for 30mm fan. Get fast shipping and top-rated customer service.




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## awake (Feb 1, 2021)

Ah, found it. As shown, the hub dimensions are .575" high with .55" OD and 10mm ID (yes, sorry, mixed units - I tend to work in both, depending on what is most convenient at any given moment). The ID is sized to take MF106 flanged bearings, so that the fan can turn on a 6mm shaft. The overall diameter of the fan is 2.25", and the blades are .375" high. The fan blades start out around .06" thick and taper to around .03".

Of course, any of these dimensions can be changed to suit the need. If you are interested, I'll be glad to generate an .STL file to the dimensions you need.


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## awake (Feb 1, 2021)

And here is a not-very-good picture to show the results when printed - it prints very nicely, and without supports:


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## Brian Rupnow (Feb 1, 2021)

We got bearings!!


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## awake (Feb 1, 2021)

I originally generated the fan using FreeCAD, but I have put together an OpenSCAD version - this will let anyone generate fans with whatever dimensions are desired. Hopefully it is sufficiently well commented that it will be easy to use.


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## Brian Rupnow (Feb 1, 2021)

I appreciate the offers of a 3D printed fan, and if I was going to be the only guy that built this engine, I would definitely take you up on the offer. However, I sell these plans all over North America. I want to find a solution that I can buy, because then the folks who buy my engine plans can buy their fans from the same source.---Brian


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## awake (Feb 1, 2021)

I certainly understand, and I hope I didn't come across as pushing this - just trying to give back in thanks for all of the information I have gained here! I have used the GPL license for the OpenSCAD file, so you are free to include it with the plans. I think. Maybe I need to change it to LGPL? In any case, my intention is for it to be freely available to all and sundry.


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## Brian Rupnow (Feb 1, 2021)

Okay---that's enough fun for one day. I kind of like the flywheel.


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## CFLBob (Feb 1, 2021)

I think that went by too fast for me to follow, but that's a steel rim and an aluminum plate cut round to fit it?  (Plus the cutouts)  How's the plate held to the rim so that it won't slip?


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## Brian Rupnow (Feb 1, 2021)

Magic----


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## Brian Rupnow (Feb 1, 2021)

I'm sorry Bob---Not really magic. My plan is to drill 1/8" diameter holes around the outer ring and the inner web and Loctite 1/8" dowel pins into place on the center of the web, as shown. That may be subject to a bit of change, but not much. I don't really want to weld anything because of heat distortion, but I may make the 1/8" pins from brass and a bit longer than necessary and then turn the o.d. of the outer ring so that all that really can seen it two round brass dots at each web spoke.


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## Brian Rupnow (Feb 1, 2021)

The round piece of aluminum was 3.50" in diameter. The inside of the heavy wall tube cleaned up at 3.428" diameter. I put in a 3.50 countebore for the aluminum web to set up against.


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## CFLBob (Feb 1, 2021)

Thanks for the multiple clarifications.  I guess the steel wall is about 1/2" thick for the entire rim?  Interesting design!  I'll keep watching.


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## Steamchick (Feb 2, 2021)

Jasonb: I notice your Practical Mechanics picture show a bloke Graving. That's a skill I have not practiced in a decade or so - since I have had "better" cross-slide lathes. I wonder how many of the readers even know what Graving is? In my local club there is an "oldish chap who spent his working life as a hand-turner of wood. His "forte" was to make a hat  - cowboy hat style with large brim - turned from a solid piece of wood - less than 1/8" thick. He the n softened the wood with steam and shaped it with the traditional vee in the middle, and curled brim. I have seen the photos of his display stand - they looked just like John Wayne could have worn! In his mid 70s he retired and sold all his wood-working stuff. Then  decided with an empty workshop to try metal-work. He was interested when I explained how my Grandfather taught me Graving as a boy. So he decided to "give it a try" - as it was similar to his skill as a wood-turner. - He reckoned it was easier than working out "which way to wind the wheels on the cross-slides"! My Grandfather repaired clocks and made all the screws, etc. by Graving. Worked to Vernier 1/20th millimeter sizes. From memory, I think his collet chuck was for 1/4" max. The motor must have been smaller than the 90W motor on my Unimat... the whole lathe only as big as a computer key-board. Maybe I'll make myself a graving tool and give it a go sometime! I have used a tool held in Mole grips in the past, but a bit cumbersome. I used to make small screws for him - thread cut using what he called a die plate. Probably around 6 or 8 BA? - Nostaglia is not what it used to be.
K2


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## Steamchick (Feb 2, 2021)

Brian, I am interested in your flywheel design. I have a Brass ring (from a fire extinguisher?). Of course pinning is an obvious way to attach the rim to spokes. - But maybe I'll use some round bar spokes if I make a flywheel from my Brass ring? And I may silver solder the assembly... Then I'll have to decide what to make for the engine! I am fascinated by your work.... carry on.
K2


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## Jasonb (Feb 2, 2021)

I've done a bit of graving and tend to use my woodworking HSS scrapers which cut quite well on most metals, bar in the tool post makes a simple rest. Did you notice in the photo that the midget engine is driving the lathe via a line shaft on the bench

If you do go with a soldered up flywheel then solder in two stages with the spokes done on the first heat and then the hub on the second heat, that way you don't get distortion when the ring shrinks as it cools. One I did described here Preston's Oscillator


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## Steamchick (Feb 2, 2021)

Thanks Jason - Good tips!
 K2


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## Brian Rupnow (Feb 2, 2021)

Today was the day to start counterboring the crank-cases. In this view, you can see that I have the counterbore for the 3/8" crankshaft bearing in place (It's a really deep one), and the large counterbore for the crankshaft, con-rod, and balance weights. There will be a second set-up in the 4 jaw to put in the counterbore for the camshaft bearings and cam. I would have been finished this side except that I had to take good wife down street to pick up a new microwave oven. In this horrible Covid winter, almost anything is a good reason to get out of the house.


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## Brian Rupnow (Feb 3, 2021)

The internal cavities are finished in the crank cases. No real drama here. I set both crankcases up in the lathe to bore the large cavity and the bearing cavity in the center of the big cavity. Then I realized that I didn't need to do that for the third and final cavity --it was done on the milling machine. Very happy to announce that with the bearings in place and with shafts running through both bearings, the crankcases still mate up and the locating dowels still slide into place. Now I have to drill about 15 holes thru the crankcases and thread some of them.


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## Brian Rupnow (Feb 3, 2021)

I just found out that this engine will be painted. My quotes came in today----$55.37 for brass to make the gear cover. $12.03 for the same sized material in aluminum.   $24.52 for enough brass to make the gas tank support in brass, and $4.97 for aluminum the same size. That is just outrageous. The "shine" on this engine will be shiny paint----Not Brass!!!----Brian


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## Brian Rupnow (Feb 3, 2021)

So there, (with a rather astonishing number of holes in it) sets the finished crank-case. Two holes have yet to be drilled and tapped for the gear-case, but I will wait until the gearcase is made before doing that. In the background you can see the flywheel with about a billion clamps on it. I was able to put a counterbore in one end of the outer rim, big enough to set the web up against. I Loctited it and put the clamps on. When the Loctite is totally set up, I will then do the drilling and pinning to hold the flywheel permanently together.


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## Brian Rupnow (Feb 4, 2021)

This morning I made the base. I have to pick up material downtown today, but it wasn't going to be ready until after lunch, so I put my waiting time to good use.


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## delalio (Feb 4, 2021)

This is turning out to be a beautiful engine. Great work. And I too will probably take you up on the purchase of some plans. I've never built an IC engine. I've mostly got into this hobby through model steam engines on a lathe. But IC is definitely an area I would love to try!  

Looking forward to the next update!


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## Brian Rupnow (Feb 4, 2021)

Home with more material. Grey cast iron for the cylinder and enough aluminum to make the outer gear case, the gas tank support, and a piece of 1/8" diameter brass rod to pin the flywheel with. That cost a grand total of $55.00. If you are an American looking at these prices I list for my builds, you can buy the same material for about 15 to 20% less, south of the Canadian border.


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## Brian Rupnow (Feb 4, 2021)

This gas tank support has more of an "artsy-fartsy" thing going on than the parts I usually make, but I like it. I think it adds a touch of beauty to an otherwise "plain Jane" engine. I have a bit more work to do on it, but I'll  save that for tomorrow.


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## scottyp (Feb 4, 2021)

Brian is not screwing around - nice progress!


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## CFLBob (Feb 4, 2021)

Brian Rupnow said:


> This gas tank support has more of an "artsy-fartsy" thing going on than the parts I usually make, but I like it. I think it adds a touch of beauty to an otherwise "plain Jane" engine.



It's a pretty support.


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## jack620 (Feb 5, 2021)

awake said:


> I originally generated the fan using FreeCAD, but I have put together an OpenSCAD version



Thanks for going to the trouble. I use Fusion360 and unfortunately it won’t open the file you posted. Will OpenSCAD export in a file format that Fusion360 can use?

Hers’s a list of compatible file types: File formats supported in Fusion 360 | Fusion 360 | Autodesk Knowledge Network


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## Steamchick (Feb 5, 2021)

Nothing wrong with Artsy Fartsy! - Looks good to me!
K2


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## awake (Feb 5, 2021)

jack620 said:


> Thanks for going to the trouble. I use Fusion360 and unfortunately it won’t open the file you posted. Will OpenSCAD export in a file format that Fusion360 can use?
> 
> Hers’s a list of compatible file types: File formats supported in Fusion 360 | Fusion 360 | Autodesk Knowledge Network



OpenSCAD can produce .stl files, and not much else - but since I originally modelled this in FreeCAD, I can export to a step file or similar from there. Will do that shortly ...


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## Brian Rupnow (Feb 5, 2021)

I couldn't install the gas tank support without machining the body of the gas tank to mount and see what it looked like in place. I'm happy with that. This afternoon I hope to make the cylinder.


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## awake (Feb 5, 2021)

jack620 said:


> Thanks for going to the trouble. I use Fusion360 and unfortunately it won’t open the file you posted. Will OpenSCAD export in a file format that Fusion360 can use?
> 
> Hers’s a list of compatible file types: File formats supported in Fusion 360 | Fusion 360 | Autodesk Knowledge Network





awake said:


> OpenSCAD can produce .stl files, and not much else - but since I originally modelled this in FreeCAD, I can export to a step file or similar from there. Will do that shortly ...



To keep from filling up Brian's thread with OT traffic, I have started another thread on this: https://www.homemodelenginemachinist.com/threads/3d-printed-cooling-fan.32893/ - I have put .step and .iges files there, along with the original FreeCAD files, plus additional explanation of how I generated this.


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## Brian Rupnow (Feb 5, 2021)

And just at the point where I was congratulating myself on what a fine machinist I was getting to be---My parting off blade decided to squirm around in the holder, and eat the center fin damn near off. Do you know what "Hubris" is?  Ah, poop!!! We'll just cut off all the lower fins and run with it. It won't affect the way the engine works--the hottest part is up near the top of the cylinder anyways.


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## Brian Rupnow (Feb 5, 2021)

Well, this is a slightly different look than I had in mind, but it will do. By the time the cylinder base gets squared off everything else gets mounted to the engine, it won't be noticeable. If anybody asks, well, "I planned it this way!!"


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## jack620 (Feb 5, 2021)

I'm just amazed at how quickly you progress Brian. It would take me weeks to get this far. Looks like it's going to be a great engine. I wish I had a milling machine.


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## Brian Rupnow (Feb 6, 2021)

And if you wonder what I've been doing for the last 7 hours, this is it. A cylinder head. It certainly is nice to have a milling machine with such tremendous headroom as this one. In this picture the head is raised almost to it's limits with the engine held in the mill vice while I drill the holes in the top of the cylinder for the cap screws which hold the head in place.


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## Brian Rupnow (Feb 6, 2021)

And what exciting things are in store for tomorrow??---A big clean up to get all of the cast iron dust and chips off my lathe and mill. Nasty, nasty stuff!!!  I may work up enough energy to pin the spokes in the flywheel with a piece of brass rod I bought, but no seven hour thrash like today.


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## Brian Rupnow (Feb 7, 2021)

Having a bit of a lazy day today. Lathe and mill clean up and maybe pin the flywheel together as per the drawing.


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## Brian Rupnow (Feb 7, 2021)

Ugly, but it seems to be working fine. Will post a shot after Loctite has set up and pins have been filed and sanded flush with outer diameter.


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## Steamchick (Feb 7, 2021)

Brian Rupnow said:


> And what exciting things are in store for tomorrow??---A big clean up to get all of the cast iron dust and chips off my lathe and mill. Nasty, nasty stuff!!!  I may work up enough energy to pin the spokes in the flywheel with a piece of brass rod I bought, but no seven hour thrash like today.


A magnet in a polythene bag is my "anti-iron dust" contraption. Turn the bag inside out to removerify the magnet (free of dust) and keep the iron dust in the bag. The black dust not picked-up will be the free carbon from the cast iron. Then a good wipe with an oiled cloth to collect any remain abrasive detritus.
But you know all that, I'm sure, Brian.


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## Steamchick (Feb 7, 2021)

Brian Rupnow said:


> And what exciting things are in store for tomorrow??---A big clean up to get all of the cast iron dust and chips off my lathe and mill. Nasty, nasty stuff!!!  I may work up enough energy to pin the spokes in the flywheel with a piece of brass rod I bought, but no seven hour thrash like today.


A magnet in a polythene bag is my "anti-iron dust" contraption. Turn the bag inside out to removerify the magnet (free of dust) and keep the iron dust in the bag. The black dust not picked-up will be the free carbon from the cast iron. Then a good wipe with an oiled cloth to collect any remain abrasive detritus.
But you know all that, I'm sure, Brian.


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## Brian Rupnow (Feb 7, 2021)

I have a shop vac that is almost as old as me. When I finish a cast iron job, I vacuum everything, wash everything down with varsol, and then wipe everything down with a clean cloth. I then apply a bit of #30 oil to the ways and spread it everywhere with my fingers.


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## Steamchick (Feb 8, 2021)

Hi Brian, Just Like I was taught in the 1960s for my school workshop job, then, when 13, my Saturday job! - When I learned the Magnet trick. That's more than 50 years ago I started work... I got quite intimate with machinery before I thought of girls - when my school friends were getting "into-mates" on the rugby pitch.
K2


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## Brian Rupnow (Feb 8, 2021)

There is more work involved with this flywheel than I like to mention, but it is nice.  You can see the top of the 1/8" brass dowels that hold the outer steel rim to the aluminum center. They cleaned up really nice. Also, you can see the steel starter hub on the near side where my electric drill starter connects.


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## Steamchick (Feb 8, 2021)

Excellent work Brian. Keep it up.
K2


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## Brian Rupnow (Feb 8, 2021)

I had the devil of a time with this rocker arm tower. Had no problem making the large piece which bolts to the cylinder head. I reamed the top hole with a 3/16" reamer, and then decided that rather than silver solder the rocker pin into it, I would machine it to have a press fit. I started out with a piece of 1/4" cold rolled and machined it to be about 0.010" oversize. then I decided to take the remaining bit off with file and emery paper, aiming for 0.189" diameter for a press fit. I sanded, and I sanded and I filed and I filed, checking every 20 seconds with a micrometer so that I didn't turn it undersize. I eventually got it down to 0.189" and started to press it into place, heating the larger part with my oxy acetylene torch to expand it a little---and it went crooked!!! Then I had to take it apart, straighten it out (burned the Hell out of my finger doing so). Then I was successful in getting it pressed into place, but I'm sure glad I wasn't paying myself machinists wages, because it took about four times longer than it should of. The good news is that while I was rooting around in my box of goodies looking for a 1/4"-32 sparkplug, I found a couple of 1/8" ball bearings that I didn't know I had. They will be perfect for my cooling fan shaft.


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## Brian Rupnow (Feb 8, 2021)

I've spent a bit of time sussing out the cooling fan, using the bearings I found earlier today while searching for a sparkplug. As it turns out, they weren't 1/8" after all, but were 3 millimeter. (which is about 0.118"). That's okay, close enough. I can make them work. I don't see any problem with the support bracket nor the pulley, but I'm afraid that  if I make a fan it will look like it was made by a cave man. It's difficult right now with this Covid thing, because I can't actually go over to Sayal Electronics and look for a fan. I've looked at a great number of fans on the internet, but for something like this I'd really like to see it before I bought it. The fan as shown is 1 5/16" outer diameter with a 3mm center hole and it blows towards the cylinder, turning clockwise when viewed from the flywheel side of the engine. I could use a 35 mm diameter metric fan. I'm not sure just what I'll do, but I'm happy to get the bracket designed and to have found some bearings.


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## Brian Rupnow (Feb 9, 2021)

I wouldn't go so far as to say I HATE making rocker arms, but they are not something I'd machine for enjoyment. And they're stuck right up on top of the engine for God and everybody to see, so they have to be done right. I've managed to use up an entire morning making these ones, but they look okay. I'm running out of "easy" things to make, but I still have some lifter guide bushings and the gas tank assembly to finish.


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## Steamchick (Feb 9, 2021)

Hi Brian. I guess you dissassemble later to drill oil ways for rockers, etc? I guess you'll put a pretty little brass oiler on top of the rocker shaft mount to feed them? That will catch the eye and distract from the rocker arms I think? 
I'm not bothered about the appearance of the rockers the way you suggest, but you could mill some grooves either side of the rockers to lose weight and make them look like "H" section castings? Knowing your work they'll be a real good looking feature then.
Cheers!
K2


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## Steamchick (Feb 9, 2021)

Hi again, Are the rockers steel?
K2


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## Brian Rupnow (Feb 9, 2021)

There!! Enough work for one day. I see that I have mislabeled these lifter guides as valve guides. Oh well, I can change the name tomorrow. Going upstairs now to drink Kahlua.----Yes the rockers are steel.


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## Brian Rupnow (Feb 9, 2021)

Steamchick---I'm not that sophisticated. No oil holes or galleries for the rockers. Just a squirt of oil before running the engine.


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## CFLBob (Feb 9, 2021)

Brian, is the gas tank steel, too?  Are you going to put on a glass end cap or something pretty like that or something like a pipe cap? 

The way I interpreted the drawings back on the early pages was a glass cap.


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## Brian Rupnow (Feb 9, 2021)

The gas tank is steel. I have been dissed by a fellow forum member on how big and clunky the pipe caps I normally use for gas caps look, and I think I agree with him. I don't think I will use any glass, but I will probably come up with something   a bit sleeker looking. I haven't totally thought it through yet, but stay tuned, it could happen this week.


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## Steamchick (Feb 10, 2021)

No Probs Brian. I am thinking more of a guy who shows his engines at our club events: Always complains that his models wear too quickly, but he doesn't make any provision for oiling, and runs long periods.. If your engine was powering something for any length of time I guess you would add some oiling. One guy built a 9 cylinder radial - said it only ran once before everything rattled and he lost compression - so never run since. He said he wasn't going to build the plane for it - so it didn't matter. Sad that all that work had such a short life. But there you go... I come from industries where the product has to last decades, or hundreds of thousands of miles, so lubrication is a prime consideration for me.
K2


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## Jasonb (Feb 10, 2021)

The rockers don't really use enough oil to warrant fitting oil cups and you would likely need caps to them so the rocking did not slosh the oil about. I tend to use a very small ctr drill to make a hole with CSK edge which is enough to hold a drop of oil applied as needed.

As for shape you can go at them with a needle file to soften them up a bit and file the main profile so it's a bit more organic or if you have CNC some fancy curves become a lot easier.  Add to that turned and straight knurled adjusters rather than cap screws and smaller hex lock nuts if you want a less industrial look. At the end of the its whatever makes the individual builder happy that really matters.


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## Steamchick (Feb 10, 2021)

Look nice!
My idea was for a single oiler in the post, with drilling to the rocker bearings.
In terms of shape, I spent most of my design career working shapes to minimise stress raisers and material. I had to double the dynamic performance of a job, while reducing cost by 25%.... not easy, but did-it while increasing the Service interval by a factor of 10. So I am keen to see other clever design ideas applied, rather than just Victorian engineering. Each to his own.

K2


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## Brian Rupnow (Feb 10, 2021)

Today I seem to be suffering from a bad case of "lazy arse". I don't feel like doing much. Maybe today I will prepare a couple of gear blanks. If I find any energy later in the day,  might even cut teeth on them.


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## Brian Rupnow (Feb 10, 2021)

I like cutting gears. The more you do it, the easier it gets. As long as you have the right cutter selected---and as long as you have the cutter vertically centered on the chuck---and as long as your depth of cut is set right---and as long as your carriage stops are set so you don't run a cutter into the hardened chuck jaws and ruin it---and as long as you count the number of rotations and remember to move the sector arms each time you cut a tooth--and remember a little cutting oil once in a while, why, there's nothing to it!!!


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## jkimberln (Feb 10, 2021)

Easier if you have a gear hobber, which I do.  Unfortunately I don't have a 24 DP hob.  I only have 20, 32, and 64.  Wonder if I can change a couple dimensions and still build your engine?  I'll have to look into that.


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## Brian Rupnow (Feb 10, 2021)

Jkimberln--Let me do a little research on this. I'm pretty sure that there is a little gear magic that works with 32 and 64 dp gears. The only two sure things right now are the center to center distance which is 1.563" and that it must be an exact 2:1 ratio. I will delve into this and post what I find out. A lot of people want to build this engine.---Brian


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## Poppy Ott (Feb 10, 2021)

I also have a gear hobber.  I have equipment to make my own form-relieved hobs, but only can do D.P. not module.  Those I have bought on Amazon, from China.  Delivery is not speedy (a couple months) but they have been good and at $80.00 the price is right.  You could look there for a 24 DP hob.


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## Brian Rupnow (Feb 10, 2021)

Okay, this I have found out so far---For 48 DP gears, they would have twice as many teeth so it would be 50 tooth and 100 tooth combination but the center to center distance would stay the same as I currently have for the 24dP gear teeth.--For 32DP gears, a 32 tooth and 64 tooth would give a 2;1 ratio and a 1.563" center distance.


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## jkimberln (Feb 10, 2021)

I've looked into the gear DP idea too and with what I have available, the easiest way to make the gears is to use 1.0 mod and cut the teeth a little deeper in order to get the tooth clearance.  That way, the tooth count and the ctc distance can remain the same.  Not ideal but it would work.  I also considered a couple pulleys and a timing belt but that might screw up the looks of the engine, plus a tensioner might be needed.  I have a couple queries out for hobs and there is the Chinese suppliers as Poppy mentions.  I hear tell that Ash Gear will also rent hobs but I've never tried that and it would probably be too expensive.


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## Eccentric (Feb 10, 2021)

I hear you Brian, making gears is fun, but like you said there is a lot of "as long as yous..."  I find my self holding my breath with each cut, each increment of the indexer, thinking to myself, "all right, I haven't screwed it up yet, only thirty seven more to go."  

You are making great progress.  It is already a great looking engine.  What people don't see is the behind the scenes work on the CAD model and creating the drawings.


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## Brian Rupnow (Feb 11, 2021)

A gearcase is being born--and so far this morning it's been a hard labour. I expect  to finish it after I get some lunch!!


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## Brian Rupnow (Feb 11, 2021)

Well!!! That took much more time than I thought it would. The fitting of the gearcase to the crankcase took longer than machining the gearcase. This is the kind of thing where you only get one chance to drill and tap the holes in the correct place in the crankcase, and not have the inside of the gearcase rubbing on one of the gears. My solution to this involves many layers of masking tape around the large gear, to the point where it will just barely fit into the cavity in the gearcase. It doesn't sound like a lot when you say it fast, but it's taken me most of the afternoon to get it to this point. I'm happy with it, but I started this morning at 8:00 and just finished up now at 3:50.


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## werowance (Feb 11, 2021)

Brian,  i use a portable ignition unit sort of like you have done on several of your engines so that i dont have to do a sperate coil and battery pack etc for each engine.  but found going from cm6 to 1/4 x 32 plug a regular coil wire wouldnt work for me.  i ended up making a decent adapter but curious if you have a setup to continue using your portable ignition/coil unit or if you will make a seperate ignition unit that will just fit the 1/4x32 setup.  long story short, im just curious to see what your setup is or how you will be for firing the plug.   looking for better solutions while still keeping the coil in a portable box and using it on different engines.


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## Brian Rupnow (Feb 12, 2021)

Werowance--some of my engine hi-tension leads with normal plug boots on the end and take a full size ignition wire, which plugs right into the end of the coil. I also have some hi tension leads from Roy Sholl that are about 3 mm in diameter.  There is a trick. Make a plug about 2 1/2" long that fits your coil, from wood. Drill the wood lengthwise with a hole just big enough for the small wire to pass thru. Push the wire thru it and bare the last 1/8" of the wire, folding it back over the leading edge of the wood. Use  a little crazy glue to keep the wire inside the wood. Then depending on which engine you want to run, use the appropriate plug wire.----Brian


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## Brian Rupnow (Feb 12, 2021)

Okay---I did build something today. Not a complex critter by any means, but now the engine has an exhaust system.


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## awake (Feb 12, 2021)

Brian Rupnow said:


> Okay---I did build something today. Not a complex critter by any means, but now the engine has an exhaust system.


Sometimes even the little parts can leave us ...

... wait for it ...

... exhausted!


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## Brian Rupnow (Feb 12, 2021)

I'm going to make a fan to cool my engine. I wanted to buy a pre made fan, but couldn't find one I liked on the internet, and the local hobby shop doesn't have anything close to what I want. Jason made his own cooling fan, and he did it very well. He posted pictures of two different fans he had made on one of the forums, and I'm impressed. I have one piece of 0.050" thick mild steel here (Which I think started life as an inspection hatch cover on an electrical box.) I designed and printed out a 10 blade fan 1.75" diameter, and glued it to the steel. Tomorrow I will drill the 3mm center hole and cut it out using my rotary table and then cut the slots between each blade on my bandsaw. The bandsaw blade cuts a 1/16" kerf and I don't have any files that thin except for a couple of ignition point files to clean up the cuts with after they are sawn. I will let you know what happens.----Brian


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## Vietti (Feb 12, 2021)

Dwight Giles in MEB described making small engine fans.  I've made three of them and rally like the look with a ss spider and riveted brass blades, 5 blades.


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## Steamchick (Feb 13, 2021)

Hi Brian, I suggest you make an anvil form - "die block" I think is a more correct term? Then each bend/twist of the fan blade will be the same. BUT practice on a piece of scrap with the die block to make sure it gives you the shape you want before attacking the cut circle. I have never done it, but my Dad told me how.... Anyway, a guy with your expertise probably knows better anyway! I just like to see if my thinking is correct. (If there is a better way, you show us all).
Well done on another interesting build.
K2


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## Jasonb (Feb 13, 2021)

It's a lot less effort to give each blade a twist with a pair of long nosed pliers, that's how I did mine


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## Steamchick (Feb 13, 2021)

You are a better twister than I am David! - The eyes can see where to hit, but the arm does its own thing - sometimes seems independent of any brain attached! (Not that the brain would be right anyway!). I have made fans - just very noisy! Apparently there's a lot of aerodynamic stuff to make them quiet and efficient. But at slow speed, almost anything will work - it just needs to look like a "proper job" - which yours does and mine never do.
Cheers!
K2


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## Rdean33422 (Feb 13, 2021)

Excellent build
I am currently building a single cylinder vertical IC engine of my own design so watching your progress closely.
I do have a couple of questions.
How will the cam gears be lubricated?
How do you determine the oil level in the crankcase?

Thanks
Ray


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## Brian Rupnow (Feb 13, 2021)

The cam gears are lubricated with gear grease for external gears (almost any thick grease will do). The cover is easily removed with two bolts if you want to apply more grease. You will see a blue bolt head just to the left of the gearcase, and a filler tube just below the gas tank. You remove the bottom bolt beside the gearcase and pour oil in the filler tube until it starts to run out the bottom hole. That is the correct level for the oil to be at. Then you put the bolt back in and you're done.


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## Brian Rupnow (Feb 13, 2021)

Today's rattlesnake roundup starts with an ignition cam. Probably one of the easiest parts on the entire engine to make. The dual set screws keep the engine from getting "out of time" if the cam slips on the crankshaft.


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## Rdean33422 (Feb 13, 2021)

OK
So when the oil is filled to the proper level and the rod is at BDC how far into the oil does the rod end extend when the engine is not running?
Thanks 
Ray


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## Brian Rupnow (Feb 13, 2021)

It's a tricky little dance, and it goes like this----There is a round plate up against the side of the crank-case which is bolted in place with flat head screws from inside the crankcase. It doesn't move. Then there is a separate plate which the ignitions points mount to, and it is a sliding fit over the previously mentioned plate, and it has a handle (not shown) that can rotate it around the previously mentioned plate to adjust timing while the engine is running, and lock it in place. The ignition cam sets on the crankshaft and is locked in place. It's a lot to figure out if you haven't seen this before, but it does allow for "dynamic" timing.


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## Brian Rupnow (Feb 13, 2021)

So here we have the second step in the fan blade saga---The outside diameter was cut using an endmill, cutting with the side of the endmill, while a 3/16" diameter bolt  was places thru the center-hole of the fan and held in my milling vice. This is a very unsafe and "grabby" way to cut, and I held things very tightly and remembered everything my mom ever said about "Brian, you're going to cut your fingers off with that jacknife!!!" Fortunately, no fingers were cut off, so then I used a big sheet metal screw to attach the fan to a piece of wood. This way I could take one cut on the bandsaw, back out, spin the fan blade 36 degrees and repeat the cut, until all the cuts were made. No deburring has been done yet, and the blades haven't been torqued to 30 degrees yet. I will make some kind of funky jig to ensure that each blade gets torqued the same amount.


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## Brian Rupnow (Feb 13, 2021)

I have a really scrofulous old drill press vice, that works for holding just about anything. Clamped to the corner of my desk, it makes a good filing jig to hold the fan in place while I file and deburr inside the slots. My ignition points file which you can see in the foreground is a perfect fit into the slots cut by the bandsaw blade. Next step will be to soak the fan in some boiling water to get the paper pattern off.


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## Brian Rupnow (Feb 13, 2021)

Well, for a first time ever fan experience, that wasn't too bad. If I had it to do again, I would use 1/16" plate instead of the 0.050" that I used, but that is what I had. I silver soldered a hub onto the one side, and right now it's setting in a jar of pickling salts to get some of the flux off, and hopefully some of the rust. Tomorrow I will figure out just how I'm going to attach the 3 mm shaft, and probably give the fan some primer paint to fill the rust pits. Sorry about the blurry picture. I'll put up a better pic when it's finished.


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## Brian Rupnow (Feb 14, 2021)

If my time was worth anything, this might be the most expensive cooling fan in the world. It is fully fabricated and uses 3mm sealed ball bearings on the fan shaft. I fabricated the 1" pulley as well. if I had known how well this was going to turn out, I would have bought a new piece of 1/16" steel plate to make the fan from. All I had on hand was a rather pitted and horrible piece of 0.050" thick metal that started life as an inspection hatch on an electrical box. I have a little cosmetic work to do on the fan yet, but now that I have the experience of making a fan, I may just buy a piece of metal and build another fan. I was going to put a groove for the drive belt into the flywheel, but it seems to track just fine as it is, and I hate to cut on the flywheel.


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## Steamchick (Feb 15, 2021)

Looks "Cool"! Brian. Much neater than my attempts!
K2


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## Brian Rupnow (Feb 15, 2021)

Someone asked the other day what the oil level in the crankcase would be. The oil level is determined by a removeable plug in the side of the crank case. This picture shows the oil level.


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## Steamchick (Feb 15, 2021)

I like it! A splash like a load of birds in a bird bath! supplies plenty of oil splash to bearings, underside of piston and cylinder walls to keep them cool.
K2


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## Brian Rupnow (Feb 15, 2021)

In the time honored offered tradition of "Making it up as I go along", today I have a con rod up on the lathe.  The overall shape of the con rod, the bolt on cap, and the bores in both ends are finished in previous steps. Here I have made up a simple fixture to which I can attach the con rod in order to turn meat away from both sides, so I end up with a raised "boss" at the big ends. What is shown is the first step, machining the side material away to expose the first big end boss. Now I will flip the part over in the fixture and do the other side "big end boss". I will probably finish up the other ends with my rotary table and milling machine.


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## Brian Rupnow (Feb 15, 2021)

Todays fun limit has been reached. We have a finished connecting rod. Sometimes I wish I had a media blaster to even out the finish on things I machine so they would show up better on camera. ah well, nobodies going to see it once it's installed in the engine. It is aluminum 6061 t6 material. I don't generally put bronze bushing shells in these con rods, as they never see heavy lugging loads and aren't run often enough to make a difference.





.


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## Eccentric (Feb 15, 2021)

Looking good Brian.  If you are to make another fan, what would you think about a thin strip of metal wrapped around the outside of the blades to protect a finger that strayed too close when the engine is running.  Think of a section of tin can cut to match the outside diameter of the fan--that sounds dangerous too.   Or maybe a shround integral to the mount?

I remember the time I was reviewing an electronic packaging design that had an exposed running fan.  I pointed to it and asked the engineer with me, "shouldn't that fan have a grill over it?"  And it took the tip of my finger right off.


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## Brian Rupnow (Feb 15, 2021)

Look at the solid model. The exhaust system sets directly above the fan (see post #136). I know the fan is there, and I know not to stick my finger in it. I no longer have to deal with "Safety Committees". They were the bane of my existence!!!


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## Brian Rupnow (Feb 15, 2021)

Here's a picture of a half grown piston. It will reach adulthood tomorrow. Why is the skirt so thick?---I really don't know. That's made from an old piston drawing that I brought forward and used on this engine. I think I'll thin that skirt down tomorrow when I have it up on the rotary table.


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## CFLBob (Feb 15, 2021)

Brian Rupnow said:


> Why is the skirt so thick?---I really don't know.



Perfect quote.  Sometimes things seem to have a mind of their own.


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## Steamchick (Feb 16, 2021)

Bob, I thought a skirt was like security doors when the tradesman's entrance door is left open... The wind blows in...
I was told a definition of skirt by an older guy in the workshop many decades ago. - A skirt hides a multitude of sins, and provides easy access to the sinners! - But "politically correct" didn't exist back then.

But (for the un-initiated) on a piston the skirt does a lot of work: 

It provides location to keep the rings square to the bore. It actually provides a bit of spring to cushion "oscillating" loads, so must be fatigue resistant. - It may even have splits to tune the "spring", for varying operating temperatures (fit to bore). Rings don't actually help align the piston - they float in the grooves, or rather the piston floats around them.
It is a sliding bearing surface that maintains the oil film upon which it floats. This surface may be reduced to small pads, that are 10~20 micron above the rest of the surface, which reduces the oil film under pressure in shear and therefore "friction"...
It conducts heat from the piston crown to cylinder walls to cool the crown (via the oil film)
It conducts heat to the oil (splash) to also help cool the piston crown.
It helps stiffen the location between the gudgeon pin bosses and the ring location
At Hepworth and Grandage I was told the "clever bits" of a piston are the skirt and ring-pack. The rest is simple mechanical support for thos 2 features. They had a lot of different studies and computer models of skirts to optimise the heat flow, stresses, stiffness, surface shape, etc. within the skirt design. There have been more designs of skirts than you can imagine, and the latest (in your car engine) are real "mini-skirts" - or "jock-flaps" - compared to the appearance of Brian's knee-length version.   Yes, Brian, it needs to be reduced a lot. (I just don't know how to design it!).
Great job you are doing.
K2


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## awake (Feb 16, 2021)

Brian Rupnow said:


> Todays fun limit has been reached. We have a finished connecting rod. Sometimes I wish I had a media blaster to even out the finish on things I machine so they would show up better on camera. ah well, nobodies going to see it once it's installed in the engine. It is aluminum 6061 t6 material. I don't generally put bronze bushing shells in these con rods, as they never see heavy lugging loads and aren't run often enough to make a difference.
> 
> 
> 
> ...


Brian, what is the size of the upper end hole / pin?


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## Brian Rupnow (Feb 16, 2021)

Awake---3/16" diameter. 
 This morning I lapped the cylinder with a 1" expanding lap using 400 grit lapping paste (you can just see a corner of it in the foreground.) until it was about 1.002 finished diameter. I had turned the piston to 1.003" diameter yesterday, An expanding lap will always leave a small "bell mouth" at the end of the cylinder, and it can work to your advantage. Once the piston would just start to go into the cylinder end, I mounted the cylinder in my 3 jaw chuck on the lathe, and using a handle I had made up to hold the inside of the piston, coated the piston liberally with 600 grit compound and slowly worked it into the cylinder with the lathe running at about 50 rpm. Once it would pass completely thru the cylinder I stopped and cleaned everything up with laquer thinners. The piston to cylinder fit is perfect.


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## Steamchick (Feb 17, 2021)

Hi Brian, In my humble experience (NOT having been a piston designer! - but I have handled a lot of pistons in the last 50 years...) - I feel the skirt "looks" thick. I don't know how to calculate the stiffness, heat flow, etc. to work out what is needed, but I do know that modern engines (since aluminium pistons became popular) try and reduce the mass at the pumping end... and on the swinging bits for that matter.
Also, (and again I don't understand the Engineering) the piston land above and between rings is always slightly reduced in diameter compared to the skirt so there is never any contact between that part of the piston and the cylinder. I guess only 0.001 smaller diameter than the skirt, but on a "race-tuned" 2-stroke reducing the top land by 0.001" eliminated the frequent seizures that had been occurring.  I guess it may be to permit "crown expansion" due to the higher temperature at that end of the piston..... or something? - Or possibly something to do with the gases (Pressure) getting to the piston rings to affect the seal? I worked with a piston guy who explained the difficult time he was having trying to reduce the clearance at the piston crown so as to reduce the volume of unburned gases from that region that caused tailpipe emissions (not a problem for you engine! A lot of his problem was getting a big enough gap so the ring pack performed correctly (Gas pressure?), avoiding any contact at that part of the piston under extreme temperature differentials when warming up... (Pistons warm very quickly, cylinders slowly, so differential expansion can cause scuffing and seizures until cylinders reach optimum temperature) and reducing the volume of "cold" trapped gas that doesn't burn.

May not be an issue with your engine/operation....
Keep up the good work, still looking good!
K2


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## Brian Rupnow (Feb 17, 2021)

I reduced the piston skirt thickness from 0.125" to 0.080".


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## Steamchick (Feb 17, 2021)

Sounds good to me... (but I'm not an expert, just an interfering old #[email protected]%=÷€《!). It probably looks relatively thick compared to the diameter. (My wife says I look relatively thick all the time, compared to others...).
K2


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## Brian Rupnow (Feb 17, 2021)

Not a lot of machining done today, but some. I made up the fittings for the discharge end of the gas tank and got everything silver soldered or J.B. Welded together and cleaned up. Gas tank is now ready for paint.  Gas tank, gear case, flywheel and rocker arms will be painted, and maybe the cooling fan. I haven't thought much about a color yet, but it will be a Tremclad color. Laying on the desk behind the engine is a piece of 1144 stress-proof steel I picked up today to become a one piece crankshaft, and a length of 1/2" brass round rod to make miscellaneous bits and bobs from.


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## oldCB (Feb 18, 2021)

Brian Rupnow said:


> Look at the solid model. The exhaust system sets directly above the fan (see post #136). I know the fan is there, and I know not to stick my finger in it. I no longer have to deal with "Safety Committees". They were the bane of my existence!!!


Ya........safety guy almost got me killed in a steel mill a couple of times........absolute morons......usally appointed by plant managers Bad subject with me too!


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## Brian Rupnow (Feb 18, 2021)

And at the closing of the day---We have two valve cages and two valves. The valves haven't been separated from their parent material yet, as I will use that for a "handle" when lapping the valves into their seats in the valve cages. The valve cages will get a hole thru the side, but won't be drilled until after they are Loctited into the cylinder head. That way I can drill the cylinder head and the valve cage at the same time. The cages will get the valve seat cut into them after they have been loctited into the head. In an earlier post I mentioned that I had picked up a weird size endmill. The maximum diameter of the valve cages is 0.375" diameter. They are sunk into a counterbore in the cylinder head. A   0.375" counterbore would have been too small, and a .438" counterbore would be too big. My "weird size" counterbore is 0.406" diameter, which should be "just right".(Makes me think of Goldilocks and the three bears).


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## Brian Rupnow (Feb 19, 2021)

Today I used my odd size endmill and put the counterbores for the valve cages into the cylinder head. The cages were coated with #638 Loctite and then pushed into place. You can't really call it a press fit, because if it was a press fit the brass cages would collapse. It's more of a "perfect sliding fit". I will wait 24 hours for the Loctite to cure, then drill inlet and exhaust ports thru the cylinder head and the valve cages at the same time. Then I will lap the valves into the seats. I also made the timing adjustment handle today. I took a quick look thru all my available compression springs to see if any of them would work as valve springs, but I haven't made up my mind yet. Also made the adapter for the Traxxas carb but forgot to include it in the picture. I attached the gas tank into it's snazzy support using J.B. Weld. I'm running out of small things to make. Still have the cams and the crankshaft to machine. The cams and lifters will be made from 01 steel and flame hardened.


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## Steamchick (Feb 20, 2021)

Hi Brian, Sounds like the weird end mill may be an imperial sized 10mm? (approx 0.040" to the 1mm. = makes it a 10mm tool bit I think?). Someone told me decades ago, that a lot of engine makers (and others) "copied" ideas from each other. The 26tpi cycle thread was an imperial copy of the metric 1mm thread pitch,  a 3 and lots of 64ths inch piston in many cars and motorcycle engines was actually the nearest to 80mm.. etc. When you consider the influx of "continental European" immigrants (Dutch, Swedish, French, Italian, Spanish, German, etc.) into the USA after 1800, it is hardly surprising that may who knew metric sizes (not feet and inches) made things "the same size as at home" - but converted them to the USA National inch sizes. Even "us Brits" have used ccs for engine displacement since Henry Ford was a tiny lad! - Perhaps being a bit closer to the technical pioneers of Messrs Otto and Carnot - and Renault (Of course!)?


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## Steamchick (Feb 20, 2021)

Kicked the calculator... (Solar powered, and only works in good light) and it confirms my calculation was just a bit off. 0.406" IS a bit weird! - doesn't match the known measurement system of this amateur...
K2


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## danallen (Feb 20, 2021)

Steamchick said:


> 0.406" IS a bit weird! - doesn't match the known measurement system of this amateur...
> K2


It is 13/32" for us in the States. Tools this size are readily available.


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## Brian Rupnow (Feb 20, 2021)

Actually, the endmill is 13/32 which is a true imperial inch size, just a bit uncommon.


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## Brian Rupnow (Feb 20, 2021)

Today seen the cylinder head drilled for intake and exhaust ports, and the muffler, carb adapter and carburetor mounted to the cylinder head. The oil filler tube was machined, along with the brass screw-on filler cap. I drove up north to see my 100 year old mother today, but she is fading badly. The nursing home is all locked down under Covid rules, and I had to get a test earlier in the week to confirm that I didn't have it.


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## Brian Rupnow (Feb 21, 2021)

I'm doing a bit of assembly this morning, and these three shots are interesting. In the bottom of the main bearing cavity in this half of the gearcase, you will see the heads of four #6 flat head capscrews. They pass thru the gearcase and attach a steel ring on the outside of the gearcase. The plate with the handle on it is the plate to which the ignition points are attached. Screwing the handle in locks the points mounting plate in place. Unscrewing the handle half a turn lets me rotate that plate while the engine is running. Since the ignition points are attached to this plate, this lets me advance or retard the ignition timing while the engine is running.


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## Brian Rupnow (Feb 21, 2021)

A shot of the other half of the gear case shows the oil filler tube pressed and Loctited into place.


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## Steamchick (Feb 22, 2021)

Hi Brian, Some of us are also in similar situations re: elderly parents. My Mother is 99 and going well - in a care home - with Dementia and has been deaf since I can remember (60+ years) so phones and Skype are no use... The care home is 8 ~12 hours drive - or a 1 hour flight, but with the current COVID quarantine we must stay within 5 miles of home and only allowed out for Essential journeys.  (2 a week to supermarket! + 1 last week to clinic for a vaccination). With a lack of available flights and accommodation we haven't seen her for 13 months, not that she knows anyway. I guess we are all going a bit stir crazy in our own ways by now....
Makes me wonder what the new "Normal" will be when COVID is behind us? = Maybe a bit "wild" like the 1920s Flappers or late 1960s Flower Power? A major financial depression? - No point even thinking about it either way! - Back to the Garage!

K2


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## Brian Rupnow (Feb 22, 2021)

Elvis has not left the building---Elvis has struggled all day with cams and tappets.   I don't make cams often enough to have all the steps memorized. Basically, that means that every time I make a cam, I have to refer to a bunch of notes I have made and try to decipher what I actually meant when I wrote them. Here we have one cam, setting in place with a mushroom head tappet. Tomorrow I will make the second cam. Piece of cake, now that I have refreshed all my memories by making the first cam.


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## Ghosty (Feb 22, 2021)

Brian, I also have the same problem, also with gear cutting, I just don't do enough of them anymore to remember it all
Cheers
Andrew


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## Steamchick (Feb 23, 2021)

Hi Brain, - oops! (typo). Brian. Perhaps (when you have an idle moment? - Ha!) you can attach some of the deciphered notes on cam-machining? - I would have to start with a circle - then use a BIG File! (+ marking blue, DTI and cam follower...). So will find it very interesting. Or maybe include with plans for the engine - then I'll buy those.
K2


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## Brian Rupnow (Feb 23, 2021)

And now we have two finished, hardened, oil quenched cams. That cam nearest the front looks a bit ragged on the edge, but it's not. The macro setting on my camera finds little flaws so small that they can't be seen by the naked eye. I have to go out to the hardware store and look at the paint color chart for Tremclad paint, and then it's almost crankshaft time.


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## Steamchick (Feb 23, 2021)

Look really good to me from over 3000 miles away!
K2


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## Brian Rupnow (Feb 23, 2021)

Uh-Oh--Something just happened. I was happily milling away a whole lot of 1144 stress-proof that wasn't going to be part of the crankshaft. Milling machine just stopped---lost all power. First I looked for the ratty little glass fuse that my old mill had, but this mill doesn't seem to have any separate little glass fuse. Next I checked the breaker in my electrical box.---It was okay. I don't know if the motor has a thermal overload cut out or not.---Doesn't have any visible reset button. Well, Poop!!! I didn't feel that much like working anyways, but I have to figure out what is happening with the mill before I can do any more.


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## Ghosty (Feb 23, 2021)

Brian, any sneaky cut out /limit /safety switches on it that could have failed.
Cheers
Andrew


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## Brian Rupnow (Feb 23, 2021)

I'll talk to their technician in Toronto tomorrow morning. It may be something simple like a reset button on the motor, but I don't see anything. It's not a huge deal to take the mill to Toronto for repair, but it's a giant pain in the xxxx to get the mill from my shop out to my garage where it can be loaded into my truck.


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## Brian Rupnow (Feb 24, 2021)

I just spoke to the technician at BusyBee and he said that the problem is 99% sure to be an "electronic board" that controls the motor. The board is only about $12.00, and he said that it should be quite simple to repair myself, so he is express shipping it up to me. Seeing that it is such a major undertaking to move my mill, I think this will be the best thing to do, and I can repair the mill "in place". Right now I'm suffering from terrible arthritis pain in my wrists, forearms, and hands, so if I take a break for a couple of days I won't feel terribly bad about it. I had an x-ray of both hands the day before yesterday, and am supposed to have a blood test  on Monday. I've had minor arthritis for years, but nothing compared to this. Ironically, the mill broke down on the very last part for this new engine, the crankshaft.


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## Steamchick (Feb 25, 2021)

Hi Brian. I have mild arthur-it us from gout... but so far nothing disabling. You have my sympathy so get well soon.
K2


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## Brian Rupnow (Feb 25, 2021)

I'm, setting here typing with a wrist brace on both right and left arms. There seems to be some confusion whether my suffering is arthritis or carpal tunnel syndrome. I've had carpal tunnel issues before, but there was no pain or swelling involved, just numb and tingly fingers. Ultimately, the numbness and tingly fingers went away on it's own. My good wife, who always seems to know more than I do about most things, has declared that I am suffering from carpal tunnel syndrome. The doctor hasn't weighed in on this issue yet, and is waiting for me to have a blood test on Monday. I've only had these wrist braces on for about 4 hours today, and I must admit that my hands do feel better than the day before. I had to go to my local hardware store to buy some ice melting salt for my concrete steps, and while I was there, I looked at the color charts for Tremclad paint. The choice came down to either cyan (sky blue) or fire red, so I went with the red. I plan on painting the gas tank, gear cover, flywheel, and the rocker arms and rocker arm support tower. The rest of the engine will remain either aluminum color or brass color, with no painted finish. I think that the fan and it's support will be semi gloss black.----Brian


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## Richard Hed (Feb 26, 2021)

Brian Rupnow said:


> I'm, setting here typing with a wrist brace on both right and left arms. There seems to be some confusion whether my suffering is arthritis or carpal tunnel syndrome. I've had carpal tunnel issues before, but there was no pain or swelling involved, just numb and tingly fingers. Ultimately, the numbness and tingly fingers went away on it's own. My good wife, who always seems to know more than I do about most things, has declared that I am suffering from carpal tunnel syndrome. The doctor hasn't weighed in on this issue yet, and is waiting for me to have a blood test on Monday. I've only had these wrist braces on for about 4 hours today, and I must admit that my hands do feel better than the day before. I had to go to my local hardware store to buy some ice melting salt for my concrete steps, and while I was there, I looked at the color charts for Tremclad paint. The choice came down to either cyan (sky blue) or fire red, so I went with the red. I plan on painting the gas tank, gear cover, flywheel, and the rocker arms and rocker arm support tower. The rest of the engine will remain either aluminum color or brass color, with no painted finish. I think that the fan and it's support will be semi gloss black.----Brian


If you have carpal tunnel, you may wish to consult with an accupucturist.  Accupuncture Might help, but if it is arthritis, I thimk it would not help.


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## johnmcc69 (Feb 26, 2021)

I think it will be nice to see this engine with some paint, it's not often we see paint on your engines.
 Nice work all around & hope the wrist pain eases off for you.

 John


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## Brian Rupnow (Feb 26, 2021)

Thank you John.  Painting is a relatively new thing for me, and I'm not really sure about how I feel about it. It does make the models more visually attractive. Richard--I always thought acupuncture was Chinese bull$hit, but a few years ago I had one hip and top part of my leg went all numb. I tried all of the modern medical treatments and therapies to fix it, and none of them worked. One of my therapists suggested acupuncture, and since nothing else had worked I said go ahead and do it . Amazingly, after only a few acupuncture sessions, the feeling was restored in my hip and leg, as good as new. I'm not nearly so suspicious of acupuncture now.---Brian


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## Richard Hed (Feb 26, 2021)

Brian Rupnow said:


> Thank you John.  Painting is a relatively new thing for me, and I'm not really sure about how I feel about it. It does make the models more visually attractive. Richard--I always thought acupuncture was Chinese bull$hit, but a few years ago I had one hip and top part of my leg went all numb. I tried all of the modern medical treatments and therapies to fix it, and none of them worked. One of my therapists suggested acupuncture, and since nothing else had worked I said go ahead and do it . Amazingly, after only a few acupuncture sessions, the feeling was restored in my hip and leg, as good as new. I'm not nearly so suspicious of acupuncture now.---Brian


I never considered it bull, but I definitely wasn't sure what it was or how it workt, but I have had similar miraculous results.  Does not work for cancer, I thimk it will not work for arthritis, but not sure.


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## Eccentric (Feb 27, 2021)

I wish you all the best Brian. I had carpal tunnel to the point I could not use my right hand and have trained myself to use a left-hand mouse. With all of the computer work you have been doing on your latest master piece, I am not surprised you are having wrist issues. It takes a concerted effort to relax your hand when using the mouse. A wrist brace has really helped me, and having a good pad under my wrist for both the keyboard and the mouse helps a bit as well.

I like your choice of fire red and look forward to seeing how it looks on the engine.  It seems there are not many of us IC builders left these days and we need to encourage and support each other.  Brian, know I am actively watching your build and have always been a fan.  Again, wishing you the best.


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## Brian Rupnow (Feb 28, 2021)

Thank you Eccentric---That was a very kind post. Whatever is wrong with my hands, I think it is more related to all of the machining I have been doing. 3d work on the computer has never bothered me. I have two wrist braces on, and am waiting for a blood test tomorrow. Whatever it is, it's damned painful and uncomfortable.


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## Richard Hed (Feb 28, 2021)

Brian Rupnow said:


> Thank you Eccentric---That was a very kind post. Whatever is wrong with my hands, I think it is more related to all of the machining I have been doing. 3d work on the computer has never bothered me. I have two wrist braces on, and am waiting for a blood test tomorrow. Whatever it is, it's damned painful and uncomfortable.


What does your butcher--I mean, doctor say about glucosamine?  It helps me a little, maybe not enough but a little.  I workt last summer in the harvest in which when I was driving the harvester, I was always gripping two objects:  with left hand, the steering wheel; with right hand, the joy-stick.  I did this for five months which meant that my finger joints were squeezed together for too many hours in the day.  This causes the joint material, cartilege, to be compressed like a sponge for too long.  This will end up in one of the forms of arthritis eventually.  Was your work in machining like that?  The thing is, if you are working for yourself, you can take a break when ever yuou like.  Working for someone else, you can't.


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## dnalot (Feb 28, 2021)

Brian Rupnow said:


> I have two wrist braces on, and am waiting for a blood test tomorrow. Whatever it is, it's damned painful and uncomfortable.



I share your pain. My hands, especially my thumbs are in pain 24/7. I was diagnosed with osteoarthritis and psoriatic arthritis. I am being treated with a biologic injection now. It helps some with the pain but leaves me so depleted that I can only work in the shop a couple hours a day. I guess getting old is not for wimps. Just keep your eyes on the prize and keep on trucken.

Mark T


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## Brian Rupnow (Feb 28, 2021)

I've has carpal tunnel syndrome before, but not this bad. Last time I had it was about 10 years or more ago, and I don't remember a lot about it. I know that they offered me surgery to correct it and I said no, and after a few months it went away by itself. I want to be able to finish this engine.


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## Brian Rupnow (Mar 1, 2021)

I've sat around the house with wrist braces on and done nothing for three or four days and I'm going crazy!!! I really wasn't happy with the cooling fan I had made from an old pitted piece of 0.050" thick plate. The process worked fine, but the pitted material looked awful. This afternoon I snooped around in by boxes of cut-offs, and found a 2" diameter piece of 316 stainless steel, just long enough to grip in my chuck jaws and turn to 1 3/4" outer diameter. I had enough material to make a fan blade 0.060" thick with a 1/8" thick x 1/2" diameter hub on it. I will investigate cutting the slots with a cut-off saw to give the sides of the blades a little smoother finish than a band-saw cut. Does anyone know if this material takes silver solder okay?


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## dnalot (Mar 1, 2021)

Yes S.S. silver solders just fine.

Mark T


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## johwen (Mar 2, 2021)

Hello Brian,
Don't Know if you know this but..
Soak your wrist *pain* in a solution of warm water and *Epsom salt* for 15 minutes. The water should be as high temperatures *can* handle. You *will* have to absorb the pulse in a solution of cold water for 30 seconds. There are MANY other things you *can do* from your own home to *cure* your *carpal tunnel* problems. The Epsom salts turns into magnesium and additionally buy a high quality dose of Magnesium capsules and take a maximum dose of this daily for all aches and pains.
!n 1991 I was going to a Chiro 3 time a week for 6 months and not one day was I without back pain. after getting onto Magnesium today at 86 I have no aches or pain and walk 5K per day 5 days per week.
Hope this helps Brian also cut out as much sugar as you can as it is acidic. Acid causes pain! Stay well. John


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## Steamchick (Mar 2, 2021)

Hi Brian,
I knew a guy who had been crippled with arthuritis. (25 years ago). He went on an acid free diet: No wine, only beer and gin (he had a huge wine cellar - a connoisseur.). No tea of COFFEE. Mineral water only, Not spring water. Seriously, everything he had ever eaten was studied and he hit the "no acid" mark - after which he recovered in a month to get back to work! He reckoned it was almost miraculous. But depends on your problem if you can starve Arthur of acid and get better, or if another problem. I have mild gout. I've been taking Turmeric all winter for the Arthur in my finger joints (damaged by cold from motorcycling all winter, and the gout). It seems to work as although the joints are a bit swollen, mostly they don't hurt. Or at least most days. In October it was 6 days pain, 1 day relief, now 1 day pain per week.
Hope you find a solution to your problem soon. Having had the carpal tunnel thing from the early years of using a computer mouse I know it took me 6 weeks before I was "good to go", and loose the wrist splint.
Cheers mate!
K2


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## Steamchick (Mar 2, 2021)

For silver soldering Stainless (nickel based alloys) you need a special flux, or suffer poor "wetting" by the fluidus. (A surface tension problem). It also copes with the higher temperature solders you are likely to use. I found Stainless 304 stays on a copper boiler didn't seal until I used the flux for stainless... "Seemed" to be held strongly, but were threaded into the copper anyway, however they all leaked at the solder to S/S interface - not good for a boiler! Cleaning the flux off needs a hard chisel, it isn't water soluble like the regular flux for copper work.
Could a friction weld work for you? - The fan is very low power! - e.g. boss with flange held in chuck for rotation: fan located on boss, and pressed onto surface with a sleeve (Axial pressure from tail-stock) NOT rotating. Run, press gently, till hot. When hot stop lathe apply pressure simultaneously and the fan may weld onto the flange of the boss...
Enjoy!
K2.


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## Brian Rupnow (Mar 9, 2021)

My greatest apologies to all who were following this thread. I was hoping to be finished by the end of February but my 74 year old body is causing me some distress right now, so I have to slow down a bit. Between carpal tunnel syndrome in my wrists and arthritis in my knees, I have been told by the doctor to back off a bit. There is the vague spectre of knee replacement surgery lurking in the background, but I doubt it will actually come to that. I will continue updating this thread (everything is completed except for the crankshaft and counterweights and spring keepers for the valves). Hang in there folks, this will get finished, just not as quickly as I had hoped.---Brian


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## Ghosty (Mar 9, 2021)

Brian,
Don't worry about the hobby, get yourself as fit as you can first, every thing else will follow
Cheers
Andrew


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## Rdean33422 (Mar 9, 2021)

Your health is the most important thing now.
Stay well

Ray


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## Steamchick (Mar 10, 2021)

Look after number 1 - then she'll be fit enough to look after you - or make the end "painless" while she inherits the Insurance! 
Stick in there Brian, Reading doesn't need that much joint movement. STAY WARM - the cold in the workshop affects me most in this season.
We'll all chat again when you are improved (unless She gets you first!).
K2


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## jamesmattioli (Mar 10, 2021)

Brian Rupnow said:


> My greatest apologies to all who were following this thread. I was hoping to be finished by the end of February but my 74 year old body is causing me some distress right now, so I have to slow down a bit. Between carpal tunnel syndrome in my wrists and arthritis in my knees, I have been told by the doctor to back off a bit. There is the vague spectre of knee replacement surgery lurking in the background, but I doubt it will actually come to that. I will continue updating this thread (everything is completed except for the crankshaft and counterweights and spring keepers for the valves). Hang in there folks, this will get finished, just not as quickly as I had hoped.---Brian


Spero molta salute per te rimettiti in forma, il motore lo finirai in futuro. Ciao


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## Brian Rupnow (Mar 12, 2021)

Okay!! I'm still fighting carpal tunnel in my hands, but today boredom got the better of me, so I've made a bit more progress. In a perfect world, I would machine all of my parts exactly to the drawings I make.---In the real world, I come close, but there are a few areas where this gets very critical.  One of these places is the width between the ball bearings in the crankcase. There is very little clearance between the inside of the ball bearings and the crankshaft, which is the part I'm making next. If there is too much clearance, then there will be issues of crankshaft endplay. The engine will still run okay, but there will be mysterious clanks and bangs issuing from the crankcase as the crankshaft revolves and slides back and forth between the bearings. If there isn't enough clearance, then the crankshaft won't revolve when the two halves of the crankcase are bolted tightly together. I don't have a tool that will reach down thru the top of the crankcase to measure the clearance between the bearings. My answer to this is to machine a couple of "sleeves" from 1/2" diameter material. One is slid over the end of a piece of 3/8" shafting and Loctited in place. After the Loctite has set up, the shaft is slid thru the bearing on one side of the crankcase and the sleeve is butted up against the inside of the ball bearing. The other sleeve is then slid over the other end of the 3/8" shaft, slid close to it's approximate position +1/2" and a dab of Loctite put on the shaft. Then quickly, before the Loctite sets up, the other half of the crankcase (with bearing in place) is slid over the shaft until it contacts the second sleeve and pushes it ahead of the bearing until the crankcases are touching each other and bolted together. After the Loctite has set up, the two crankcase halves will be separated and I can measure the distance outside to outside of the two sleeves which are loctited to the shaft. This will tell me what the exact distance is between the two ball bearings so I can machine the crankshaft to fit with about 0.010" of overall clearance.


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## Steamchick (Mar 13, 2021)

Clever Brian (as usual)! I may have followed basically the same approach (if I had come across this problem) as I was taught as a teenage apprentice... Insert a shaft all the way through the pair of bearings (True-size to check alignment is perfect) where there is a pair of sleeves also inserted between the bearings: The sum of these sleeves is rather less than the total width between the bearings. But each sleeve is fitted with a locking screw. So the sleeves can be slid up to touch the inside faces of the bearings, locked in place (access through the crankcase mouth) and then upon splitting the cases afterwards the dimension you want is available, - Same process, just locking screws instead of Loctite. Also used to determine shims for gear-box shaft end-float correction, etc. - or any other internal dimension. Can also be used externally, as the length of rod can be measured, the thickness of sleeves measured and the projection of rod from an external sleeve can me confirmed with a depth mic or other. The a simple computation subtracting the "external elements" from the rod length gives the overall outside dimension of the bearing pair.
Show us a pig (of a problem) and we have many ways to kill it!
It's good to be reminded of these techniques! Thanks Brian.


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## Brian Rupnow (Mar 13, 2021)

This morning bright and early, and I'm looking for things I need to do yet. I'm about to make the valve spring retainers from brass, but I needed some reference dimensions from the valve springs I am going to use first, so I thought I might as well make a drawing of the springs while I had them out being measured.


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## Brian Rupnow (Mar 13, 2021)

Here we have both valves, valve springs, and spring keepers assembled in the cylinder head. The valves were lapped into the seats first with #320 grit lapping paste, then 400 grit lapping paste, and finally with 600 grit lapping paste. After lapping the valves had the "handle portion" above the taper trimmed off and about .025" left at 5/16" diameter before the taper begins.


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## CFLBob (Mar 13, 2021)

Brian, I thought you were slowing down?  

Don't hurt yourself.  

Don't mean to be preachy, but I've seen far, far too many people just getting over an injury re-injure themselves because "it doesn't hurt that bad" and they plunge back to it.


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## Brian Rupnow (Mar 13, 2021)

CFLBob--Thank you for your concern. I am feeling a bit better, and there is always a good chance of dying from boredom. The work to install the valves and make the keepers was one of those things I could do mostly while setting down.


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## Tim Wescott (Mar 13, 2021)

Hey Brian -- you may have covered this already, but what are you doing for keepers on the valve stem ends?  The ones that I've dealt with (old Toyotas and even older Chevys) were split cones that engaged with a shallow groove on the end of the valve stem.  I can't see successfully scaling that down unless you have Awesome Machining Powers.


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## Brian Rupnow (Mar 13, 2021)

Tim---End of valve is cross drilled. Valve spring retainer has  flange around it. Valve spring retainer pin fits cross-ways thru valve and flange on spring retainer keeps it in place.


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## Tim Wescott (Mar 13, 2021)

OK.  Interesting.  Thanks.


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## Brian Rupnow (Mar 14, 2021)

This is something worth mentioning---I find that these small, slow running 4 cycle engines work well with a total valve opening of 0.080" to 0.100". This of course is determined by the shape of the cam.  It is always a good idea after the valve springs and valves are installed to use a finger to open the valve fully, and assure that the spring will actually let the valve open by about 0.025" more than that. If the spring compresses fully and the valve isn't opening as far as the cam dictates, something is going to bend or break. You will either bend the rocker, bend the pushrod, or (rarely) break the camshaft.


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## Brian Rupnow (Mar 15, 2021)

With my newly repaired mill, I was finally able to turn my round piece of 1144 stessproof steel into a bar. I swear to God, there is as much work getting the material from a round bar (which is the only shape you can buy) to a piece of flat bar as there is in all the rest of the crankshaft machining. I milled one side flat, then used the bandsaw to cut the other side flat, then used the mill again to machine the third side flat. I haven't machined any of it down to finished size, because I'm trying to machine it in a manner to keep ahead of any bending or twisting of the material as internal stresses are released. 1144 doesn't move much, but it does move.


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## Brian Rupnow (Mar 15, 2021)

The crankshaft is up on the lathe being turned. In this view, I have just finished machining the con rod boss, and the con-rod is setting in place for a trial fit. All of the turning was done with the carbide nosed cut-off tool in the picture.


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## Richard Hed (Mar 15, 2021)

Brian Rupnow said:


> The crankshaft is up on the lathe being turned. In this view, I have just finished machining the con rod boss, and the con-rod is setting in place for a trial fit. All of the turning was done with the carbide nosed cut-off tool in the picture.



Did that carbide make a nice clean cut?  What speed did you go at when you got down to the thickness of the diameter?  Did you polish it afterwards?

Oh, woe are we--I forgot till now, it is the Ides of March, the unholy day Caesar was murdered!  Also the day after Einstein's birthday.


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## Brian Rupnow (Mar 15, 2021)

Carbide made a beautiful cut at about 200 rpm. I hit 0.375" right on the money, did a very small amount of polishing clean up.


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## stihl1master (Mar 15, 2021)

Brian Rupnow said:


> This is something worth mentioning---I find that these small, slow running 4 cycle engines work well with a total valve opening of 0.080" to 0.100". This of course is determined by the shape of the cam.  It is always a good idea after the valve springs and valves are installed to use a finger to open the valve fully, and assure that the spring will actually let the valve open by about 0.025" more than that. If the spring compresses fully and the valve isn't opening as far as the cam dictates, something is going to bend or break. You will either bend the rocker, bend the pushrod, or (rarely) break the camshaft.


is it the pictures, r the was seat are extremely over size ??


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## Brian Rupnow (Mar 15, 2021)

The valve seats are not oversize. they are part of the valve cage.


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## Steamchick (Mar 16, 2021)

Tim Wescott said:


> Hey Brian -- you may have covered this already, but what are you doing for keepers on the valve stem ends?  The ones that I've dealt with (old Toyotas and even older Chevys) were split cones that engaged with a shallow groove on the end of the valve stem.  I can't see successfully scaling that down unless you have Awesome Machining Powers.


Hi Tim, I'll try and answer for Brian, so he can carry-on making and doing his excellent write-ups. 
Actually, it isn't beyond the machining skills of most hobby machinists to make split collets - but usually they make parallel collets instead of the tapered collets on full-sized production engines. (Which are designed to minimise material mass and fatiguing stresses). Remember the ""Toyota" et al manufacturers want to guarantee 150,000 miles in 10 years use... that's 3000 hours without failure - so they design and manufacture for valves and collets to be so under-stressed they'll almost never fail in 3 times that life.
A simple rectangular groove 0.020" ~  0.040" deep in the stem of the valve with simple cylindrical split collets to engage in the spring-cap - a hole counter-bored maybe 0.040" ~0.080" larger than the valve stem clearance hole, with collets to suit, will be perfectly adequate and machinable by most. BUT this engine is so simple and under-stressed that the pin and hole arrangement that Brian is using will be OK - and simpler to manufacture.
Does that answer your question adequately?
Unless I mis-understand why you chose the pin arrangement, Brian? - Keep up the excellent work.
K2


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## Tim Wescott (Mar 16, 2021)

@Steamchick : it is utterly irrational, but if I built a model stationary engine, I'd feel bad if I didn't put it to some use where it would have the opportunity to deliver value until it wore out.  Even if it was just some "hobby" value, like running the generator that runs a model train track or something.

This is _not_ to be construed as a judgement on y'all -- you guys are sane. I'm the one tetched in the head.


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## Richard Hed (Mar 16, 2021)

Tim Wescott said:


> This is _not_ to be construed as a judgement on y'all -- you guys are sane. I'm the one tetched in the head.


Don't be too sure of that.  Why, after all, four of us who live in this here body, all agree that the fifth one is the only one who is not sane--you NEVER want to talk to HIM!

Also, I agree, even a model should do something like run a generator or a wheat grinding machine.


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## Brian Rupnow (Mar 16, 2021)

And there we have it boys and girls.  A completely finished crankshaft!! It turned out nice, no visible runout. Now I get to hitch up my horse and drive over to the physical therapist to see what he is going to do about my numb fingers and sore wrists.


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## Steamchick (Mar 16, 2021)

Tim, "You are a better man than I.... " to quote Kipling. I just like to see them running, but do try and add a generator and lamp if possible. But I'm not really into winding generators, so bicycle dynamos are my convenient loads to make them work..... As to powering a railway... any scale.. Wow!
Enjoy.
But my comment wasn't meant to denergrate anything you all do, just a recognition that models generally are made to demonstrate a principle, and such things as precision ground valves and collets for durability are not necessary for the duty cycle of the models. Hence I was defending what I thought Brian's decision for pinned valve spring caps would be.
Sorry if I raised your blood pressure, not my intent.
K2


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## olympic (Mar 16, 2021)

Brian Rupnow said:


> With my newly repaired mill, I was finally able to turn my round piece of 1144 stessproof steel into a bar. I swear to God, there is as much work getting the material from a round bar (which is the only shape you can buy) to a piece of flat bar as there is in all the rest of the crankshaft machining. I milled one side flat, then used the bandsaw to cut the other side flat, then used the mill again to machine the third side flat. I haven't machined any of it down to finished size, because I'm trying to machine it in a manner to keep ahead of any bending or twisting of the material as internal stresses are released. 1144 doesn't move much, but it does move.





Brian Rupnow said:


> And there we have it boys and girls.  A completely finished crankshaft!! It turned out nice, no visible runout. Now I get to hitch up my horse and drive over to the physical therapist to see what he is going to do about my numb fingers and sore wrists.





Brian Rupnow said:


> And there we have it boys and girls.  A completely finished crankshaft!! It turned out nice, no visible runout. Now I get to hitch up my horse and drive over to the physical therapist to see what he is going to do about my numb fingers and sore wrists.


Nice crankshaft Brian!

Though I'm not a machinist, I recently tried my hand at this (first time I tried something like this), using mystery steel from a trailer hitch drawbar, and it worked after I annealed it overnight in the wood stove.

What I would like to know is what kind of band saw you used and how you cut the steel to size. I have a Chinese 4x6 band saw that doesn't seem to like working in vertical mode, so I had to resort to chain drilling to come close to a decent size before I turned it down in the lathe.

The result has, as far as I can tell, about .0015 TIR, so I think I can live with it; otherwise I'll just have another go at it.

Any advice on cutting steel with a Chinese band saw would be welcome.


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## Brian Rupnow (Mar 16, 2021)

I have an old 16" vertical wood cutting bandsaw to which I added a second jackshaft and pulleys to bring the rpm down to a speed for cutting steel. It works great--I use a 3/4"  x 1/16" metal cutting blade. My cuts ae all straight cuts---the blade is too wide to cut curves with.


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## olympic (Mar 16, 2021)

I wondered about that. I may have to look into modifying my "real" band saw with a countershaft.

Thanks.


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## Steamchick (Mar 17, 2021)

I have a hacksaw... and a sore shoulder.
K2


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## olympic (Mar 17, 2021)

Steamchick said:


> I have a hacksaw... and a sore shoulder.
> K2



Good point. I use my hacksaw a lot, too.


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## Brian Rupnow (Mar 17, 2021)

Olympic--if you already have a wood cutting bandsaw and want to use it for wood and/or metal, instead of putting in a jackshaft, take a look at a 3 speed standard automotive transmission. That way you can select one speed for cutting wood, and one for cutting metal, and a third gear for anything in between. you wouldn't use the reverse gear for anything.


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## Brian Rupnow (Mar 17, 2021)

Progress is being made. Today the engine is assembled with the finished crankshaft for the first time, and everything goes round and round like I had anticipated. Next step will be to machine a set of counterweights, a couple of pushrods, and do some creative painting.


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## Steamchick (Mar 17, 2021)

Excellent work Brian! You are appreciated for your quality of work and speed of build as well as the frequent postings of your progress, trials and tribulations. A joy to read and watch!
Just hope the pain in your hands etc. can be resolved soon.
Thankyou!
K2


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## olympic (Mar 17, 2021)

Brian Rupnow said:


> Olympic--if you already have a wood cutting bandsaw and want to use it for wood and/or metal, instead of putting in a jackshaft, take a look at a 3 speed standard automotive transmission. That way you can select one speed for cutting wood, and one for cutting metal, and a third gear for anything in between. you wouldn't use the reverse gear for anything.


Great idea, Brian. I have an old Pinto 4-speed out in the shed, and that may just work.

And I can indeed use the reverse, for undoing mistakes.

Looks like all those big power lines across the road from you haven't affected your brain at all....


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## Brian Rupnow (Mar 17, 2021)

I don't have the best set-up for wintertime painting here.  It goes something like this--Get all the parts to be painted ready for paint and held in spare vices, vise grips, or anything else that's handy. Set up my big garbage pail with a board on top outside my office door. Set all the fixtured parts outside on the board, then paint them outside. After 10 minutes, move all the fixtured pieces inside where it's warm to dry. Wait one hour---change all the fixtured pieces around so the unpainted side is exposed, then carry them all back outside to set on the garbage pail. Spray paint again outside, then carry them all back inside to dry. It keeps most of the paint stink outside.  I may get a bit high setting in my office until the paint is totally dry, but ya gets your kicks wherever you can----


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## Brian Rupnow (Mar 17, 2021)

Olympic--where the heck are you, and how did you know about all my power-lines?


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## Richard Hed (Mar 18, 2021)

Brian Rupnow said:


> I don't have the best set-up for wintertime painting here.  It goes something like this--Get all the parts to be painted ready for paint and held in spare vices, vise grips, or anything else that's handy. Set up my big garbage pail with a board on top outside my office door. Set all the fixtured parts outside on the board, then paint them outside. After 10 minutes, move all the fixtured pieces inside where it's warm to dry. Wait one hour---change all the fixtured pieces around so the unpainted side is exposed, then carry them all back outside to set on the garbage pail. Spray paint again outside, then carry them all back inside to dry. It keeps most of the paint stink outside.  I may get a bit high setting in my office until the paint is totally dry, but ya gets your kicks wherever you can----


Oh, well the wacky weed is legal here for a few years now.


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## pileskis (Mar 18, 2021)

Brian Rupnow said:


> Olympic--where the heck are you, and how did you know about all my power-lines?


Google earth!!  Your address is on all of your drawings you publish! 
I’ve seen your power lines too!!

By the way, next time the truck or the satellite flies by, can you make sure your lawn is cut and those bushes trimmed up???

Sid


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## Brian Rupnow (Mar 18, 2021)

This morning yielded a pair of bolt on counterweights for the crankshaft. They fit inside the crankcase as shown, and don't interfere with any thing as they rotate. I am almost ready to begin final assembly. I always go a little bit crazy deciding how to set the cams on my camshaft, but that is the only difficult part of what is left.


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## Brian Rupnow (Mar 18, 2021)

Ah, Google Earth.--Forgot about that. I try and keep anything illegal inside where the spy satellite can't see it!!!


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## Tim Wescott (Mar 18, 2021)

pileskis said:


> Google earth!!  Your address is on all of your drawings you publish!
> I’ve seen your power lines too!!
> 
> By the way, next time the truck or the satellite flies by, can you make sure your lawn is cut and those bushes trimmed up???



On the control line stunt forum, my location is given in lat/lon, with enough digits of precision that you can land a smart bomb on the toilet in my garage.

I like checking Google Earth's maps from time to time, to see what the state of my field was when they took it -- there's a control line circle out there that's sometimes mowed, sometimes not.


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## Tim Wescott (Mar 18, 2021)

Brian Rupnow said:


> This morning yielded a pair of bolt on counterweights for the crankshaft...



I was wondering why no counterweights when I saw that shaft -- now I know.  I assume you didn't want to start with an even _bigger_ hunk of steel from which to machine the whole thing in one piece.


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## Brian Rupnow (Mar 18, 2021)

Yes Tim, that is why the counterweights are bolt on.---Brian


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## olympic (Mar 18, 2021)

Brian Rupnow said:


> Olympic--where the heck are you, and how did you know about all my power-lines?


No Google Earth needed here; I used to live in Barrie, and know Carson Rd. well.


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## Vietti (Mar 18, 2021)

How did you size your counterweights?

John


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## Brian Rupnow (Mar 18, 2021)

We're not set up to run yet, but my, it certainly is pretty!! Tomorrow is "Make gaskets day" and try to set up the cams to the correct position on the cam shaft.


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## Brian Rupnow (Mar 18, 2021)

Vietti--it was "best guess". there is a proper way to set the counterweight, but it is rather involved and requires a weigh scale that I don't have.


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## Tim Wescott (Mar 18, 2021)

Vietti -- Balancing Small Engines by ET Westbury: Page 2

But no single-cylinder engine is going to be perfectly balanced; the best you can do is minimize the vibration.  And some designers purposely under- or over-balance, depending on whether they want the engine vibration to be weighted (as it were) more toward vibrating in a circle or along a line.  So doing it b'guess & b'gosh isn't bad -- especially for a light engine.

Brian, the sensitive scales are cheap, and these days you can buy them from Amazon.  This means you don't need to go to a head shop and ask for a "cocaine scale".


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## CFLBob (Mar 18, 2021)

Tim Wescott said:


> Brian, the sensitive scales are cheap, and these days you can buy them from Amazon. This means you don't need to go to a head shop and ask for a "cocaine scale".



Don't overlook Horrible Freight.  I got a good gram scale there.


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## Brian Rupnow (Mar 19, 2021)

This morning I remade the fan from 316 stainless. For some reason I found this fan to be difficult to make. It steps outside the bounds of normal machining, and seems to have about a thousand sharp edges that are difficult to get to with anything bigger than an ignition points file. It definitely looks better than the previous fan which I had made from a badly pitted piece of 0.050" metal I had laying around. It tucks in under the exhaust system, which should be enough to keep my fingers out of it.---And before you rush to tell me---I know that the paint isn't going to stay on the o.d. of the flywheel with that o-ring running on it. The plan is to sand all the paint off the outside diameter of the flywheel before I use it.


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## Brian Rupnow (Mar 19, 2021)

CFLBob--Harbor freight doesn't sell in Canada.


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## Tim Wescott (Mar 19, 2021)

Brian, I suspect we have opposite aesthetic sensibilities here, but  I'd leave that flywheel painted, and run the engine long enough so that the paint is just naturally worn off by the belt.

Shiny metal surfaces that got that way by honest wear says "this is a hard-working machine" to me.


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## Brian Rupnow (Mar 19, 2021)

And if you wondered where the electrics are, there they are, tucked in behind the flywheel. When the flywheel is installed, they are hidden in behind it.


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## Brian Rupnow (Mar 20, 2021)

The gaskets are all made and installed (except for the one between the crank-case halves). The ignition timing has been set. In this picture I am setting the exhaust valve opening with a printed degree wheel and a pointer attached to the crankshaft. This valve is easy to set. I just loosen off the set screws holding the small gear to the crankshaft, rotate the flywheel until the piston is at the very top of it's stroke (as determined by a a hex wrench down the sparkplug hole resting on top of the piston), this corresponds with the zero degree mark on the degree wheel.  Then turn the flywheel until the pointer is pointing at 25 degrees before bottom dead center and lock the crankshaft in position. Then I turn the large gear on the camshaft in the appropriate direction, until the cam just contacts the lifter and starts to move the rocker arm. Then I tighten the set screws in the small gear on the crankshaft in that position.  Setting the intake cam position is going to be considerably more difficult, as I have no access to the cam to lock it to the cam shaft. I will have to calculate the degrees of offset between the intake and exhaust valve and remove the camshaft from the engine to set that. For the sake of the picture I have turned the flywheel and crankshaft to a position that shows the pointer.


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## Brian Rupnow (Mar 20, 2021)

I'm doing some pondering here, and it has to do with the rotational position of the intake cam. Both of my cams are exactly the same shape, and both of my valves are exactly the same shape. Top dead center and bottom dead center of the piston are exactly 180 degrees apart. My exhaust valve is set to begin opening 25 degrees before bottom dead center and to close at about 35 degrees after top dead center.--If I position my cams to be exactly 180 degrees apart, then it stands to reason that my intake valve will begin to open about 25 degrees before top dead center and close at approximately 25 degrees after bottom dead center.  I'm not certain how this valve timing will effect the performance of the engine, but it certainly makes it a lot easier for me if I can just position the cams to be 180 degrees to each other.--Does anyone have thoughts on this?---Brian


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## Ghosty (Mar 20, 2021)

Brian,
This is the cam layout that I use, may be some help.
Cheers
Andrew


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## TonyM (Mar 21, 2021)

.


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## Charles Lamont (Mar 21, 2021)

IMHO that is too late for the exhaust and too early for the inlet. You would do better to open the exhaust about 40° before bottom dead, and close not later than 20° after top dead. 20° before and 40° after would be OK for the inlet, but a bit later might be better, down to 10° before and 50° after. That would put your cams 210° crankshaft rotation apart, or 105° on the camshaft.


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## dsage (Mar 21, 2021)

I agree with Charles. You're not going to get much vacuum (low intake charge and low power) if you leave the exhaust open that late. A 10 to 20 deg after TDC closing would be more typical and effective. You're just going to be sucking exhaust back into the intake instead of fuel.
Perhaps this explains your comments in the past of your engines not having much power??
Check out Crane Cams (or many others) for typical cam timing specs. Pick one for a stock replacement application.


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## Brian Rupnow (Mar 21, 2021)

Okay, working with the cams I have made, (which have 120 degrees of angular contact ) that means that it affects 240 degrees of crankshaft action. so, I begin to open the intake 15 degrees before top dead center and it closes 45 degrees after bottom dead center. the exhaust begins to open 30 degrees before bottom dead center and closes 30 degrees after top dead center. The angular difference between the cam lobes is approximately 100 degrees when fixed in place on the cam shaft. The following bit of arcane knowledge is something i researched and read about a few years ago when I built my opposed twin i.c. engine.

Now let me see if I can get my head around this. The piston is moving from top dead center to bottom dead center on the power stroke, with both valves closed. 30 degrees before bottom dead center, the exhaust cam which is leading begins to open the exhaust valve. Since there is a 1:2 relationship between crankshaft revolution and camshaft revolution, that translates to 15 degrees of camshaft rotation.

As the piston reaches bottom dead center and begins to travel up on the exhaust stroke, the exhaust valve stays open during the full upwards travel of the piston which represents 180 degrees of crankshaft rotation, or 90 degrees of camshaft rotation. Then as the piston reaches top dead center on the exhaust stroke, the exhaust valve stays open for 30 degrees of crankshaft rotation (15 degrees of camshaft rotation) during the intake stroke before it fully closes. This adds up to a total of 240 degrees of crankshaft rotation, or 120 degrees of camshaft rotation.

So—Let’s back up a little bit to where the piston is coming up to top dead center on the exhaust stroke with the exhaust valve wide open. 15 degrees of crankshaft rotation (7.5 degrees of camshaft rotation) before the piston reaches top dead center, the intake valve begins to open. It stays open thru the full intake stroke of the piston (180 degrees of crankshaft rotation, 90 degrees of camshaft rotation, and then as the piston reaches bottom dead center on the intake stroke and begins to move upward on the compression stroke, the intake valve stays open for an additional 45 degrees of crankshaft rotation, (22.5 degrees of camshaft rotation.)

This adds up to a total of 240 degrees of crankshaft rotation, (120 degrees of camshaft revolution).

So---we see that the exhaust cam and the intake cam must in this case have the same profile, since they must both be “active” an equal number of degrees of rotation. We also see that there is a total of 45 degrees of overlap at top dead center where both intake and exhaust valves are open at the same time.---this is typical of a “mid-range power/speed”  engine. Hi speed/ hi-performance engines can have a greater overlap, while slower running engines must have a smaller overlap.

Now, there is a marvelous calculation used to position the intake and exhaust cams rotationally in respect to one and other. I have read this calculation enough times to make my head explode, and will repeat it here:

“Take the total of the valve open periods, divide by 2, subtract the total valve overlap and divide the result by 2”

So—the total of the valve open periods is 480 degrees of crankshaft rotation, divided by 2= 240 degrees.

240 degrees -45 degrees of overlap=195 degrees. Then 195 divided by 2=97.5 degrees of rotational separation between the intake and exhaust cam lobes.

This information was gleaned from a number of sources, but primarily from information found in “Model Four Cycle Gasoline Engines” by C.L. Mason and in “Miniature Internal Combustion Engines” by Malcolm stride.

I laid this out in 3d cad, independently, and came up with a lobe separation of  97.43 degrees, which confirms the long winded mathematical approach.


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## Tim Wescott (Mar 21, 2021)

That seems like an awfully long valve duration for a slow engine.  I'm +1 on the suggestion made by @dsage to look at commercial cams -- but to that I'd add that even a boring old stock cam in an automotive application is designed for some degree of extra time to give the valves time to do their work.  By the 1950's American engines were designed to idle at 500 RPM, and to turn up to somewhere between 2000 to 3000 RPM depending on how feisty the engine designer was feeling.  For engines displacing 30 cubic inches per cylinder that's definitely getting into the range where you need to give the air some time to get a clue that it's supposed to be moving and get underway.

So if you're going to start with a "boring old stock cam" grind, I'd suggest that you don't go any _more_ in overlap or duration for a low-speed motor.

Edit: if you're amenable to just copying full-scale practice, I'd recommend starting with an older lawnmower engine.


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## Charles Lamont (Mar 21, 2021)

I still think you have the exhaust timed too late. Don't worry about opening the exhaust too early.

For example, my E T Wesbury designed Seagull (which you saw over at MEM, on it's second day running, you asked a question) is not designed as a performance engine, but rather as a 'flexible, docile' low compression engine, designed for 'collar work'. It has a 130° exhaust cam, opening 60° before bottom dead, and closing 20° after top dead. The 120° inlet is timed at 10° before TDC, and 50° after BDC.

OTOH, Westbury's Sealion is a performance OHC design, and you can hear the rorty nature of several examples on YouTube. That has a 140° exhaust cam, opening a whole 70 degrees before bottom dead, and closing, yup, 30° after top dead - but as I said, it is a sporty job.


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## Charles Lamont (Mar 21, 2021)

Brian, at a gallop through, I don't understand you calculation. It seems to be unnecessarily complicated anyway, and I am not surprised it is causing brain pain. I have just done a couple of pencil sketch timing diagrams using your (eccentric) timing angles, and they show me the cams are 97.5° apart, as per your calculation. Timed symmetrically 15-45 for both, they would be at 105°.


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## Brian Rupnow (Mar 21, 2021)

I get lost in this cam timing business, and the only thing holding me back from running the engine is setting the cams. I will set it up to run with the last numbers I gave and see what happens. In the best possible case, the engine will run and we'll all be happy. In the worst possible case, the engine won't run, and I'll have to pull it apart to change the cam timing. I do thank you guys for chiming in and helping.---Brian


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## dsage (Mar 21, 2021)

It will run as you have it.
If you want to play afterward adjust the valve lash a bit larger. I'm not sure if your mechanism will tolerate that (push rods need to be in pockets ??) That will make the vales open later and close earlier. I your case you may pick up a bit of power. Of course you'll lose some lift but....


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## johwen (Mar 22, 2021)

For a smooth running engine at lower speeds an inlet opening at 10- degrees BTDC and exhaust closing 15 to 30 ATDC. This allows the inertia of the exhaust to act upon the early opening of the inlet valve to start the intake mixture to start on its way. Opening the exhaust valve early say around 50-60 degrees BBDC is OK as the combustion has done most of its work up to around 100 degrees ATDC. Keep up the great work Brian. Bare in Mind that mild timing will give low end performance and vice versa transfer power higher in the rev range. Because your cams can be individually timed start off with a mild valve overlap and then change the timing varying the overlap with say inlet and then exhaust then both until you are happy with the results. John


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## Brian Rupnow (Mar 22, 2021)

This is another shot of setting the exhaust cam in the correct position, using a degree wheel and a dial indicator. I kept setting it over and over again "by eye", and each time it ended up in a different rotational position. Finally I resorted to a dial indicator so I could actually see the needle start to move when turning the cam gear by hand. I wanted to get the exhaust cam positioned correctly before pulling things apart to set the intake cam. What I have now seems to be repeatable, so I think it's time to pull the engine apart and set the intake cam, using the exhaust cam as reference.


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## dsage (Mar 23, 2021)

That's a sound procedure. One I've used many times to check final cam timing. Assuming your rockers are not a 1:1 ratio if you move your dial indicator over to the top of the valve rather than the top of the push rod and remove all the lash you can also measure your valve lift while you're at it.
BTW. If you intend to have a bit of valve lash, you should measure at the valve to get the actual valve timing since the lash will effectively alter the timing. (as I mentioned before) lash will effectively cause the valve to open late and close early.
Looks good to me.


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## Steamchick (Mar 23, 2021)

Tim Wescott said:


> Brian, I suspect we have opposite aesthetic sensibilities here, but  I'd leave that flywheel painted, and run the engine long enough so that the paint is just naturally worn off by the belt.
> 
> Shiny metal surfaces that got that way by honest wear says "this is a hard-working machine" to me.


I agree Tim. - As long as the thing doesn't end-up messy with the belt slipping on young fresh and tender paint... It is only driving the little fan so probably "flea-loading". so should be OK. A bit of violin bow rosin on the o-ring will help prevent slippage as well. And if it is as precise as we all expect from Brian's work it will leave a tidy narrow line of shiny steel when the paint has worn off. 
Brian,
I agree with your balancing philosophy: On more than one engine I have simply used the "unbalanced" casting" parts of the flywheel to off-set the worst of the natural imbalance. I usually get rid of most of the primary imbalance that way, and somehow it is nice to see the engine balanced, but not to electric motor levels, so there is still a tremble from secondary and tertiary harmonics, etc. but nothing damaging. I'm sure you have spun the engine by hand to check (feel) the reduction of vibration by adding those balance weights, so you know they are close enough, before you connect the valve train?
Can you let us know the valve timing, and ignition timing you will set?
Good work Sir!
K2


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## Brian Rupnow (Mar 23, 2021)

Somehow, I'm not getting any joy from the cams that I made. I can set them to open at the exact time that they are supposed to, but they are staying open too long. The only thing that will account for that is  that instead of having 240 degrees of interaction with the crankshaft (120 degrees of camshaft), I am getting much more than that. I have spent most of today measuring and adjusting and I have to stop now and think about what I am going to do.


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## werowance (Mar 23, 2021)

Brian, its looking very impressive.   for some reason i stopped getting update notices so hadnt seen updates since your carple tunnel on your hands.  you have progressed alot.  by chance do you have any close up shots of your new fan while its installed?  it looks great and am just curious about the bends and tweaks it had to have.  hoping a close up will show it better.

at any rate looking forward the running video  which i know wont be long from now


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## Brian Rupnow (Mar 25, 2021)

Yowee!!!--Something very, very strange is going on.  I just couldn't believe that my cams were far enough out to cause the issues I've been having with valve timing. I have spent three days going over everything I have done while building this engine, and nothing jumps out at me. Then, this morning, I loosened of the set screws in both timing gears, put a mark on a single tooth of each gear, and turned the small gear by hand. Since I'm running an exact 2:1 ratio, the marks on the two gears should line up, then be out of line by exactly 180 degrees, then line up again on the second rotation.---but that's not happening. On every second rotation, the alignment marks are out by one tooth, and gaining on each revolution. How can this be???  So, next thing was to count the number of teeth on each gear. The small gear has 25 teeth just like it's supposed to have. The large gear has 48 teeth, not 50 like it's supposed to have!!! How can this be--The center to center distance on the crankshaft and camshaft are correct for a 25 tooth and a 50 tooth gear. And the two gears mesh okay!!! I've never had this happen before. Next move will be to check my drawings and engineering information and remake the big gear.--What a strange, strange thing.


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## awake (Mar 25, 2021)

Oh, well, that should be no problem. The engine will be correctly timed every now and then, when everything lines up again - surely that will be good enough?

 Joking aside, glad you found this - this is the sort of error that can be so hard to detect!


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## BaronJ (Mar 25, 2021)

Brian Rupnow said:


> Yowee!!!--Something very, very strange is going on.  I just couldn't believe that my cams were far enough out to cause the issues I've been having with valve timing. I have spent three days going over everything I have done while building this engine, and nothing jumps out at me. Then, this morning, I loosened of the set screws in both timing gears, put a mark on a single tooth of each gear, and turned the small gear by hand. Since I'm running an exact 2:1 ratio, the marks on the two gears should line up, then be out of line by exactly 180 degrees, then line up again on the second rotation.---but that's not happening. On every second rotation, the alignment marks are out by one tooth, and gaining on each revolution. How can this be???  So, next thing was to count the number of teeth on each gear. The small gear has 25 teeth just like it's supposed to have. The large gear has 48 teeth, not 50 like it's supposed to have!!! How can this be--The center to center distance on the crankshaft and camshaft are correct for a 25 tooth and a 50 tooth gear. And the two gears mesh okay!!! I've never had this happen before. Next move will be to check my drawings and engineering information and remake the big gear.--What a strange, strange thing.



Hi Brian,

It is a bit like the "out by one" error when programming !
I recall something about the number of teeth plus 2 when calculating gears.


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## awake (Mar 25, 2021)

N+2 is used for calculating the OD of the gear blank - the pitch diameter is calculated from N, and the OD is calculated from N+2.


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## Brian Rupnow (Mar 25, 2021)

HELP!!!---I'm losing it this afternoon. I have a 90:1 ratio rotary table. I'm using a 20 hole divider plate. My chart says that for a 50 tooth gear I need one full turn of the handle (which gives 4 degrees) and 16/20 of a complete turn. When I made this 48 tooth gear (which was supposed to be 50 tooth) I turned the crank on the rotary table one full turn and 16 open holes. Obviously, that was wrong. Doing some layout work with my cad system, it seems that The 16/20 should have been 15 holes plus one more space to where the crank pin engages with a hole in the divider plate.  If I'm right, then that may account for the wrong number of teeth on my gear. Somebody sort me out please---I've looked at this until I'm going cross-eyed.---Brian


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## coulsea (Mar 25, 2021)

The more you think the more confused you get. you don't count the hole that it is already in, it should go into the sixteenth hole. because you are 4 holes short of a full turn it should form a pattern and every 5th tooth you will be back to your starting hole. (it is early in the morning and i am only on my second coffee so the 5th tooth may be wrong but there will be a repeated pattern)


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## ICEpeter (Mar 25, 2021)

Hello,
Brian, I am sure your dividing head is equipped with a shear on top of the hole plate that you set to include the number of holes between the two shear legs, that are required to move your gear blank in the fraction part (16/20) of moving the required distance for tooth cutting. Typically, you set the shear to include the number of holes you need to repeat (15) when cutting your 50 teeth gear whereby the left leg of the shear is against the pin that is in the current hole and the other leg of the shear is positioned clearing the 15th hole. That means the shears span includes / covers 16 holes (15 plus one where the pin is in) When you turn the handle to make one full turn of the gear blank you keep turning until the pin is over the shears other legs hole and put the pin in there. Then move the shear until its new position, left leg, rests again against the locator pin. Repeat for all 50 teeth. I am not sure if I explained it properly and understandably, if not my apology.
Peter J.


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## awake (Mar 25, 2021)

90 / 50 = 1-40/50 = 1-4/5, or (since you are using a 20-hole index), 1-16/20. Thus, you need to turn one full revolution plus *16* holes, not 15 - so when the pin is in position 1, you will next turn a full revolution and go on until the pin is in position 17 - *17*, not 16.

What is really confusing me is that, if you made the previous gear by using 15 holes rather than 16 in a 20-hole index - in other words, 1-15/20 = 1-3/4 turns each time - you would have produced a 51.4 tooth gear - it should have been very obvious that something was wrong when you got to the end. To get a 48 tooth gear, you would need to use 90 / 48 = 1-42/48 = 1-7/8 holes. IOW, you would need to be using a different indexing circle (e.g., a 16-hole circle, with your gap set to turn 1 revolution plus 14 holes each time).


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## ICEpeter (Mar 25, 2021)

awake said:


> 90 / 50 = 1-40/50 = 1-4/5, or (since you are using a 20-hole index), 1-16/20. Thus, you need to turn one full revolution plus *16* holes, not 15 - so when the pin is in position 1, you will next turn a full revolution and go on until the pin is in position 17 - *17*, not 16.
> 
> What is really confusing me is that, if you made the previous gear by using 15 holes rather than 16 in a 20-hole index - in other words, 1-15/20 = 1-3/4 turns each time - you would have produced a 51.4 tooth gear - it should have been very obvious that something was wrong when you got to the end. To get a 48 tooth gear, you would need to use 90 / 48 = 1-42/48 = 1-7/8 holes. IOW, you would need to be using a different indexing circle (e.g., a 16-hole circle, with your gap set to turn 1 revolution plus 14 holes each time).




Well, Brian, to check how it works out you can manually turn the handle 50 times plus using either 16 holes within the shears span or 17 holes as awake says. It maybe hard on your hands since you have an arthritis condition I understand but doing it without actually cutting the gear will give you piece of mind when after 50 positions you end up returning at the starting point with 50 teeth divisions  where you wanted to be. Once you went through that exercise you will have confirmed the setting for a 50 tooth gear wheel.
Peter J.


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## coulsea (Mar 25, 2021)

as awake said. Looking at the charts you must have made the 48 tooth gear correctly or it would be obviously wrong as in part of a tooth. the simple solution is to re make the 25 as a 24 with a slightly shallower cut on the teeth (just make up for half the difference in OD, and have twice the backlash). no one will know.


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## ICEpeter (Mar 25, 2021)

coulsea said:


> as awake said. Looking at the charts you must have made the 48 tooth gear correctly or it would be obviously wrong as in part of a tooth. the simple solution is to re make the 25 as a 24 with a slightly shallower cut on the teeth (just make up for half the difference in OD, and have twice the backlash). no one will know.



Brian,
I attached a file for you from Little Machine shop referring the use and set up of a dividing head. About page 4 or 5 there is a description about the use of the shear and how to set up the shear span. I am sure that will answer your question of the "How To" It confirms what I said in my post 271 Please take the time to read the Little Machine shop article.
Peter J.


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## Brian Rupnow (Mar 25, 2021)

The little machine shop rotary table is a 72:1 ratio, not a 90;1 ratio like the one I have.--Shouldn't change the process though. My theory about this debacle is this---If, in setting up to cut a 50 tooth gear I went one hole too far each time, then the spaces between the teeth will be a very small amount larger each time I cut a space. This means that there will eventually be less room on the gears pitch diameter for teeth than was intended---but it's damned odd that it worked out so evenly to 48 teeth, and that it still meshed with the 25 tooth gear.


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## ICEpeter (Mar 25, 2021)

Brian Rupnow said:


> The little machine shop rotary table is a 72:1 ratio, not a 90;1 ratio like the one I have.--Shouldn't change the process though. My theory about this debacle is this---If, in setting up to cut a 50 tooth gear I went one hole too far each time, then the spaces between the teeth will be a very small amount larger each time I cut a space. This means that there will eventually be less room on the gears pitch diameter for teeth than was intended---but it's damned odd that it worked out so evenly to 48 teeth, and that it still meshed with the 25 tooth gear.



Brian,
I realize that. I believe whats important to you is the description on page 4 and 5 relating to the number of holes to be included in the set up of the span of the shear / sector arm to indicate how many number of holes should be included when setting up the sector arm for the correct number of holes. The way you went about, you included one hole to much and should have done 15 holes plus the one the pin was in, i.e. the span of the sector arm would have included 16 holes total - 15 open holes and one hole where the locator pin is in. You weren't sure about that and I hoped the Little Machine shop article would help with that.
Peter J.


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## werowance (Mar 25, 2021)

Mine is 90 to one.  here is the chart for mine if it helps


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## werowance (Mar 25, 2021)

and if it helps even more here is the pdf from grizley - which is the one i use but mine is a phase ii brand but the dividing plates and all seem to be the same.

g1760_m.pdf (grizzly.com)


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## Jasonb (Mar 26, 2021)

Quadrant should be set to have 17holes between the fingers. 1 for the pin and the 16 you need to move

If you set the quadrant to one hole too many you would have moved 4deg + (17/20) x 4 = 7.4deg spacing which gives about 48.5 teeth so you may have had some slip an the arbour too.

here is a Video I did to go with my "Milling for beginners" book/articles you can see there are the 6 holes required plus the one the pin goes into between the fingers.


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## Steamchick (Mar 26, 2021)

Thankyou Brian, for sharing this. I haven't got the gear nor the need - nor bottle - to try gear cutting. But I do enjoy and appreciate your honesty in sharing your mistakes and all the guys who jump in to help and advise. This is a humbling but enjoyable experience witnessing kindness in text to help you resolve your problems. (I didn't ever expect you to have any such issues - it is like finding out that Teacher is a normal person!).
Hope the hands are getting better?
K2


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## awake (Mar 26, 2021)

ICEpeter said:


> Brian,
> I realize that. I believe whats important to you is the description on page 4 and 5 relating to the number of holes to be included in the set up of the span of the shear / sector arm to indicate how many number of holes should be included when setting up the sector arm for the correct number of holes. The way you went about, you included one hole to much and should have done 15 holes plus the one the pin was in, i.e. the span of the sector arm would have included 16 holes total - 15 open holes and one hole where the locator pin is in. You weren't sure about that and I hoped the Little Machine shop article would help with that.
> Peter J.


Peter, what you are describing would be correct if he needed to move 15 holes at a time, but that would result in the ratio of 1-15/20 = 1-3/4, which would give 51.4 teeth. He needs to move 16 holes at a time, so 16 + 1 for the pin between the sector arms.


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## Brian Rupnow (Mar 26, 2021)

After much head scratching and reading the responses on three different forums, I come up with this. The math appears to be correct. On the first gear I cut which ended up with 48 teeth and not the 50 I was aiming for, I was going one space too many  before each cut.
What I have shown here is what the correct set-up should have been to get 50 teeth.


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## awake (Mar 26, 2021)

I don't want to beat this horse to death, but I can't resist one more post.

The problem with relying on charts has been described above: the charts are based on a table with a certain ratio in the worm gear. If your table doesn't match that ratio, the charts will be completely, utterly wrong. A secondary issue is that you may or may not have the same set of indexes as are covered in the chart.

That is why I depend on the math rather than on any charts - that, and because the math is really rather simple. Let's take a dividing head with a worm gear ratio of 60:1. None of the charts mentioned above cover this table ... but not to worry. I want my gear to have N number of teeth in one complete revolution. How many complete turns of the handle will it take to achieve one complete revolution of the gear blank? 60 - because the worm ratio is 60:1. So I need to divide those 60 turns by the N teeth that I need to cut: 60/N. This tells me exactly how much I need to turn the handle for each tooth.

Let's say that my goal is 32 teeth. If I plug 60/32 into the calculator, I get 1.875 - but this is a place where fractions are better than decimals, so let's do it the old fashioned way; 60/32 = 1 remainder 28, or 1-28/32, which can be simplified to 1-7/8. Now I just need to find an index circle based on a multiple of 8 - 16, 24, 32 ... any of these will do. For whatever index circle I use, I will convert 7/8 to match: 14/16, 21/24, 28/32. So if I use a 24 hole index, I will need to turn the handle 1 full revolution plus 21 holes.

As discussed above, that means I need to set the sector arms up to span *22* holes - one for the current location of the index pin, and then 21 more to achieve the desired 21/24 ratio.

Okay, describing it like this above, I have to admit it may sound complicated. But really, the key is to remember that you want N teeth out of R revolutions of the handle, where R is the ratio of your dividing head.


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## Jasonb (Mar 26, 2021)

There is also the problem of a couple of charts that come with the imported R/Ts have one or two errors in them


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## Tim Wescott (Mar 26, 2021)

So just put a bigger flywheel* on it, stick your nose in the air, and explain to people that it's a 4800 stroke engine.  An external valve that swaps the exhaust with the intake when the cam is exactly 180 degrees out of what it should be might be a good idea, but then it'll be a 2400 stroke engine.

* much, much bigger.


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## Tim Wescott (Mar 26, 2021)

Or throw in the towel, use a 1:1 gear ratio, and put pen clickers in your lifters: Engineers Explain How Click Pens Work - Pen Vibe

(And if the facetiousness irritates rather than amuses -- say so and I'll try to stop.  It's just that you've gone and made exactly the kind of mistake that I might have, so I'm abusing you with exactly the kind of humor that I'd aim at myself in a similar situation).


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## Brian Rupnow (Mar 26, 2021)

As far as I know, I made this gear using exactly the same math inputs as all my other gears. I didn't end up with any half teeth or unusually thick teeth. That's why it is such a puzzler. I have made many, many gears and never had a problem. I made this exact same gear for the Rockerblock engine and it has the correct number of teeth. If I made any mistakes with this gear it was probably from using one space to many on the divider plates. I'm going to make it again this afternoon using the information in the drawing I posted. I will let you know how that turns out.---Very, very weird!!!


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## dnalot (Mar 26, 2021)

I made the Adrino rotary table for dummies.  Gear making since then has been easy.

Mark T


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## Steamchick (Mar 27, 2021)

Don't beat yourself up over this one Brian. Use the "age" excuse and say " can't remember what I did".  It gets sympathy as well as the help everyone is providing. I am now old enough to get away with that one, and I assume you are my Senior?
Whatever, this has been a most interesting thread because things didn't come out right first time. And very educational for amateurs like me!
Thanks,
K2


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## awake (Mar 27, 2021)

Jasonb said:


> Quadrant should be set to have 17holes between the fingers. 1 for the pin and the 16 you need to move
> 
> If you set the quadrant to one hole too many you would have moved 4deg + (17/20) x 4 = 7.4deg spacing which gives about 48.5 teeth so you may have had some slip an the arbour too.
> 
> here is a Video I did to go with my "Milling for beginners" book/articles you can see there are the 6 holes required plus the one the pin goes into between the fingers.




One note that I would add to this video for the sake of beginners: don't forget that rotary tables and dividing heads have some backlash. As a result, you never want to "back up" to the desired position; always move forward so that the backlash is taken up. (If you overshoot, move backwards far enough to go past the backlash, then come "forwards" to the desired position.)


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## Brian Rupnow (Mar 27, 2021)

Okay--Here we go, second time around!!--And this time it has 50 teeth, and it meshes fine with the 25 tooth gear on the engine, at the correct centers for a 25 tooth and a 50 tooth gear. Why did the other (first) 50 tooth gear end up with 48 teeth?---I have absolutely no idea. The blank size was the same, the material was the same. I must have set the sector arms at one hole more than they should have been set at on the 20 hole divider plate. That is the very first gear that I've made that  didn't come out right---I've cut about 40 gears prior to the bad one. We'll remember that gear forever now, and double check my machine settings before I make any more gears.


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## Ghosty (Mar 27, 2021)

Brian,
We all make minor mistakes, just cut a 24 tooth gear and you will have another set, then, just design an engine to take them.
Cheers
Andrew


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## Brian Rupnow (Mar 27, 2021)

No, that gear is too weird to keep around. If I keep it, sooner or later I will use it and then not be able to figure out what happened to my gear ratios. Into the garbage with that sucker. I have a hard enough time remembering the things I do right without having to remember the things I did wrong.


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## Richard Hed (Mar 28, 2021)

Brian Rupnow said:


> No, that gear is too weird to keep around. If I keep it, sooner or later I will use it and then not be able to figure out what happened to my gear ratios. Into the garbage with that sucker. I have a hard enough time remembering the things I do right without having to remember the things I did wrong.


Why not just mark on it with indelible ink the number of teeth and hang it on the wall?


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## johwen (Mar 28, 2021)

Bury it Brian and mount it on the cross. Those fairies at the bottom of the garden are the culprits they sneak around at night and change settings. they have been to my place too, sometimes often. John


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## Brian Rupnow (Mar 28, 2021)

Engine is reassembled and almost ready to go. Today I took a bit of time and made an adapter with 1/4"-32 threads on the end, which will screw into the sparkplug hole. It is hollow, and has an airline attached to it. I will screw it into the sparkplug hole tomorrow and hook a regulator onto it and apply some air pressure. This will let me see if I have any leaks in the intake or exhaust valve or around the ring.


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## gartof (Mar 28, 2021)

Brian Rupnow said:


> Engine is reassembled and almost ready to go. Today I took a bit of time and made an adapter with 1/4"-32 threads on the end, which will screw into the sparkplug hole. It is hollow, and has an airline attached to it. I will screw it into the sparkplug hole tomorrow and hook a regulator onto it and apply some air pressure. This will let me see if I have any leaks in the intake or exhaust valve or around the ring.


Brian  did you single point that thread?


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## Brian Rupnow (Mar 29, 2021)

No, I used a die.


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## Brian Rupnow (Mar 29, 2021)

This morning I screwed my new adapter into the sparkplug hole and cranked up the pressure on the air regulator. This pressurized the cylinder, and immediately showed a massive head gasket leak. There is a ring of material about 0.080" thick on the cylinder head that fits into the top of the cylinder to locate it accurately, and somehow when I tightened the head bolts I had the cylinder head "cocked" enough that it didn't squeeze the head gasket evenly all the way around. This was remedied by removing the head and trimming away a bit of the gasket, then reinstalling the cylinder head and tightening the bolts properly so that the head gasket was held tight all the way around. Next thing that showed up was that I didn't have enough clearance between the exhaust rocker arm and the pushrod, so the valve was never closing. A bit of adjustment fixed that. That was the only major air leaks that were showing up on that test. Next, I filled the gas tank with Coleman fuel and turned on the ignition, and cranked the engine over with my variable speed drill. It did suck the fuel up thru the transparent fuel line, and it gave a few rather anemic blasts of smoke from the exhaust and was firing, somewhat erratically.  Okay---I'm good with that for preliminaries. Going to eat some lunch now, and hope for better results this afternoon.


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## glue-itcom (Mar 29, 2021)

Brian Rupnow said:


> The gaskets are all made and installed (except for the one between the crank-case halves). The ignition timing has been set. In this picture I am setting the exhaust valve opening with a printed degree wheel and a pointer attached to the crankshaft. This valve is easy to set. I just loosen off the set screws holding the small gear to the crankshaft, rotate the flywheel until the piston is at the very top of it's stroke (as determined by a a hex wrench down the sparkplug hole resting on top of the piston), this corresponds with the zero degree mark on the degree wheel.  Then turn the flywheel until the pointer is pointing at 25 degrees before bottom dead center and lock the crankshaft in position. Then I turn the large gear on the camshaft in the appropriate direction, until the cam just contacts the lifter and starts to move the rocker arm. Then I tighten the set screws in the small gear on the crankshaft in that position.  Setting the intake cam position is going to be considerably more difficult, as I have no access to the cam to lock it to the cam shaft. I will have to calculate the degrees of offset between the intake and exhaust valve and remove the camshaft from the engine to set that. For the sake of the picture I have turned the flywheel and crankshaft to a position that shows the pointer.


Looks like you could fit a neoprene o-ring on the fan pulley and just run it on the surface of the flywheel. Might be easier than a big belt around both.

Really like the design


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## Brian Rupnow (Mar 29, 2021)

Nigel---that is what I am using for a belt.---A neoprene o-ring.---Brian


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## werowance (Mar 29, 2021)

hi Brian,  not to beat a dead horse on the gear but if i ever have a scrape or bruise that i have to explaine to someone then i call it a massive bar fight and i won or i ran etc.  so call it "well i was having a GREAT time doing something" lol

at any rate i see you are using a 1/4 x 32 plug over the usual cm6 you often use.   i just want to watch and see your setup for that with your external ignition kit.   i use an external ignition kit as well, i made an adapter that works just fine but am interested in how you and everyone else does it.  assuming your going to use your portable ignition unit.


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## dsage (Mar 30, 2021)

Brian:
While you have the pressure testing setup you can measure your "real" valve timing by using your degree wheel and listening for the valves to open and close. Just for piece of mind that it's as expected.


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## Brian Rupnow (Mar 30, 2021)

Werowance--Normally I use the 10 mm sparkplug because it is available thru PartSource as an automotive part. however, on this cylinder head design, there wasn't enough room for a 10 mm plug. Thats why I went to the 1/4"-32 plug.  DSage--You can't hear these valves opening and closing. You have to do it by eye when you see the rocker arm start to move, or with a dial indicator as I showed in an earlier post.----Brian


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## Brian Rupnow (Mar 30, 2021)

Werowance---everything you asked about my ignition power box in this thread.---Brian





						Power Box
					

Yes, I know, its a rather strange thread title. While I wait for CNC parts to arrive for my Opposed Piston engine, I am thinking of my collection of i.c. engines. I now have the Webster, the Kerzel hit and miss, the Atkinson engine, the Odds and Ends engine by Philip Duclos, the "Rupnow engine"...




					www.homemodelenginemachinist.com


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## dsage (Mar 30, 2021)

Brian Rupnow said:


> Werowance--Normally I use the 10 mm sparkplug because it is available thru PartSource as an automotive part. however, on this cylinder head design, there wasn't enough room for a 10 mm plug. Thats why I went to the 1/4"-32 plug.  DSage--You can't hear these valves opening and closing. You have to do it by eye when you see the rocker arm start to move, or with a dial indicator as I showed in an earlier post.----Brian



To clarify:
With the air pressure applied to the cylinder through the spark plug hole you should be able to hear the exhaust valve open / close by the air pressure release / cut off in the exhaust pipe and the intake open / close at the carb. Then you take note of those points on your degree wheel.


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## oldengineguy (Mar 30, 2021)

Brian; Been following this build with great interest. Just looked back at the Mar 3 post of installed fan . Is it going to stay together at 7500 RPM ? Assuming 5 in flywheel and 3/4 in fan pulley its gonna be buzzing at 1000 engine RPM.   Just saying,    Colin


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## Brian Rupnow (Mar 30, 2021)

Oldengineguy---I'll let you know if it flies apart.---Brian


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## werowance (Mar 30, 2021)

_Brian appreciate that (the link),  my ignition unit is very similar to yours.  full size ford style coil , using regular points, on off switch, ballast resister etc.  i guess what i was really wanting to see is how you brought the spark from that coil over to the 1/4 32 spark plug.  i made an adapter for mine which i am ok with the result but this is something that i feel i could do better at and just am curious to see how you bring the coil wire from the top of the ford style coil and adapt it down to the smaller plug.   the cm6 would actually accept a normal ford coil plug  wire where the 1/4 x 32 needs something smaller. so wanted to learn about your solution as many do their own little built in coil just for that engine where you often use your portable coil system.   and i also think thats a good idea and do the same._


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## Brian Rupnow (Mar 31, 2021)

Okay Werowance---Here you go.---Find a piece of wooden dowel that is a "good" fit into the end of the coil, and long enough to stick out thru the hole in the box about 1" when it is seated in the coil.  Drill a hole lengthwise thru the piece of wood, big enough to run the insulated coil wire completely thru it. The coil wire should be about 18" long between the sparkplug boot and the bare end which fits into the wood. Cut about 3/4" of insulation away from the non sparkplug end of the coil wire. Coat the last 3" or 4 " of the stripped end of the coil wire and coat it with slow setting glue and push it thru the wood until the bared end sticks out of the wood. Fold the wires back over the outside of the wood, coat them with glue and smooth them against the wood. Now, when dry, you can insert the wood thru the hole in the box into the coil.---If you require a different sparkplug boot, make up a second coil wire assembly. the 1" of wood which extends beyond the side of the box lets you grip the wood in your fingers and pull it completely out, then you can push in a different coil wire assembly.


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## Brian Rupnow (Mar 31, 2021)

A pressure test of the cylinder indicates that I have a very leaky head gasket just below the inlet from the carburetor.  I'm not certain why, but I will pull the head off and take a look. I generally don't have problems with leaky head gaskets, and since this is the second time a head gasket leak has been indicated I will have to closely check the cylinder head and cylinder to make sure there is not some mechanical issue preventing the head gasket from sealing.


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## Brian Rupnow (Mar 31, 2021)

YES!!! Engine is up and running on it's own. Right now I need to grow about three more hands to run the starter (my 3/8" variable speed drill) and the throttle and the timing lever, but we are running. HAPPY DANCE!!! A video will follow when I get to it.


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## oldengineguy (Mar 31, 2021)

Congratulations! Hooray! On to the next. Want drawings ASAP... Colin


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## Brian Rupnow (Mar 31, 2021)

Here we go---first run!!! Tomorrow I will spend a bit of time taming this beast, but it's up and running. Joy Joy  Happy Happy---the complete plan set of detail and assembly drawings are finished, and can be purchased thru Paypal for $25 Canadian funds. (There are 50 drawings).


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## Brian Rupnow (Mar 31, 2021)

The head on that engine requires two long and two short head-bolts. I had mistakenly used four long bolts, so two of them on the sloped side of the piston bottomed out before tightening the head down correctly. Once I realized what I'd done and replaced two of the bolts with shorter bolts, the head came down into place and sealed all the way around on the head gasket.


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## Tim Wescott (Mar 31, 2021)

Brian Rupnow said:


> The head on that engine requires two long and two short head-bolts.



Your production department should have a word with Engineering about that.


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## Tim Wescott (Mar 31, 2021)

Does the fan keep it cool enough?  It looks good.


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## Brian Rupnow (Mar 31, 2021)

Thanks Tim--I won't know about how effective the fan is until I get some more run time tomorrow.---Brian


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## Smokey Joe (Mar 31, 2021)

Congrats Brian. Looks and sounds great.
Joe


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## werowance (Mar 31, 2021)

Brian Rupnow said:


> Okay Werowance---Here you go.---Find a piece of wooden dowel that is a "good" fit into the end of the coil, and long enough to stick out thru the hole in the box about 1" when it is seated in the coil.  Drill a hole lengthwise thru the piece of wood, big enough to run the insulated coil wire completely thru it. The coil wire should be about 18" long between the sparkplug boot and the bare end which fits into the wood. Cut about 3/4" of insulation away from the non sparkplug end of the coil wire. Coat the last 3" or 4 " of the stripped end of the coil wire and coat it with slow setting glue and push it thru the wood until the bared end sticks out of the wood. Fold the wires back over the outside of the wood, coat them with glue and smooth them against the wood. Now, when dry, you can insert the wood thru the hole in the box into the coil.---If you require a different sparkplug boot, make up a second coil wire assembly. the 1" of wood which extends beyond the side of the box lets you grip the wood in your fingers and pull it completely out, then you can push in a different coil wire assembly.


Brian, im sorry but i am talking about the 1/4 x 32 side of things  how did you adapt down to it?  i guess what i am asking is i would like to see your coil wire adaptation to the smaller plug.  from your description above im getting you are speaking of the coil side and not the plug side?  or am i mistaken?  sorry but the coil side i have down pat.  its the smaller plug side that i am adapting down and my adapter works but something i just want to see more of because just because i made something that works doesnt mean that i did it right or that it cant be done better


but want to say CONGRATS,  IT RUNS! and LOOKS GOOD.  with all caps because it deserves it!


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## werowance (Mar 31, 2021)

sorry to post again,  but after reading what i said i should say -
 i really just want to see how you did the plug wire on the spark plug side.  not the coil side. photos are good explanations are great to. but dont want to push it with my questions


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## Brian Rupnow (Apr 1, 2021)

I buy pre made sparkplug wire ends along with the appropriate size plug-wire from Roy Shol in the USA.


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## Brian Rupnow (Apr 1, 2021)

I love these Traxxas 4033 carburetors. They work so well on 1" bore engines. I have built a number of my own carburetors, and they work very well, but they are kind of like sparkplugs.---I can buy them cheap, so why bother building them? This philosophy may not agree with other machinists out there, but it's the way I feel. I have one problem with the 4033 carbs---If left alone on the engine, the engine vibration makes the throttle advance to the point where the engine is screaming wide open, which is somewhat terrifying. I have solved this by machining a throttle lever with a built in compression spring at the pivot point and a link to the Traxxas throttle. This works, but it is always  a bit more work and sometimes looks out of place. Does anyone have a simple solution to this issue? Someone suggested that I run some crazy glue into the pivoting throttle body to stiffen it up, but I think that is more likely to ruin the carburetor.----Brian


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## Brian Rupnow (Apr 1, 2021)

This is my engine with what I call my "Casey Jones throttle lever" A couple of Belleville washers between the throttle arm and the throttle arm mount  will keep the throttle arm from moving under vibration. A 1/16" diameter wire link ties it to the throttle lever. That way the throttle doesn't open or close unless I manually move the lever.


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## CFLBob (Apr 1, 2021)

Brian Rupnow said:


> This is my engine with what I call my "Casey Jones throttle lever" A couple of Belleville washers between the throttle arm and the throttle arm mount  will keep the throttle arm from moving under vibration. A 1/16" diameter wire link ties it to the throttle lever. That way the throttle doesn't open or close unless I manually move the lever.


I think I'm going to put one of those onto my Webster.  It doesn't vibrate out of place since my modification, but it's not secure either.


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## Tim Wescott (Apr 1, 2021)

Brian Rupnow said:


> ... I have one problem with the 4033 carbs---If left alone on the engine, the engine vibration makes the throttle advance to the point where the engine is screaming wide open, which is somewhat terrifying. ...



Just looking at a picture of one, it appears to be a bog-standard RC carburetor.  Does the throttle arm come off?  If you replaced that bellows seal with a right-sized O-ring, or put a spring inside it you may be able to add enough friction to the thing so it'll stay in place.  (Or throw the bellows away and replace it with a spring -- I've never seen a bellows in that spot in an RC carb, so I'm not sure if it's really necessary.  I think if it were me I'd take it off and see what happens, without recommending that anyone else do so.)

Basically, it's designed to be driven by a servo in an RC car; for that service friction is a bad thing, so to the extent that they're going to exert any effort at all in that area, it'll be to make it as free-moving as possible.


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## Brian Rupnow (Apr 1, 2021)

Tim---the Traxxas 4033 carb has a very clever design. Turning the throttle arm does two things. First, it opens the main passage for more air flow, as you would expect a throttle type carburetor to do. However, the throttle arm is on a very coarse pitch thread so that when it swings to the open position it also opens up the main fuel jet to allow more fuel to flow along with the increased air flow. That rubber bellows is what allows the throttle arm and inner venturi to both swing and move axially without letting air leak in from the atmosphere.----Brian


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## Tim Wescott (Apr 1, 2021)

Brian Rupnow said:


> Tim---the Traxxas 4033 carb has a very clever design. Turning the throttle arm does two things. First, it opens the main passage for more air flow, as you would expect a throttle type carburetor to do. However, the throttle arm is on a very coarse pitch thread so that when it swings to the open position it also opens up the main fuel jet to allow more fuel to flow along with the increased air flow. That rubber bellows is what allows the throttle arm and inner venturi to both swing and move axially without letting air leak in from the atmosphere.----Brian



First: Gotcha on the function of the bellows -- so if you did anything to increase friction, you couldn't touch that.

Second: Twin-needle carbs, as you describe, are the current "bog standard" for RC planes.  20 years ago they were cutting edge.  Now, it's only the most entry-level of entry level engines that use air-bleed carburetors -- and those engines are all going south, with the "low power, heavy, easy to use" market segment being swallowed whole by electrics.


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## Brian Rupnow (Apr 1, 2021)

I've decided that since I have the time, with no other engine builds planned, that I will machine a much swoopier throttle mounting bracket. Since this engine already has a decidedly "swoopy" gas tank mount, it might as well have a "swoopy" throttle mounting bracket as well. Nobody in Barrie carries Belleville spring washers, so I called Brafasco in Barrie and ordered a couple of dozen of them.


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## Tim1974 (Apr 2, 2021)

Any thoughts on running that carb on a 9 cylinder radial with 1 inch bore ?


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## Brian Rupnow (Apr 2, 2021)

Not really Tim. I don't think it would be big enough, but I really don't know.---Brian


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## Brian Rupnow (Apr 2, 2021)

Today I finished up my "Casey Jones" throttle and linkages. I don't have my Belleville washers yet, so I put a small neoprene o-ring in between the throttle arm and the piece it is attached to, to keep the arm from moving out of position. Tomorrow I will test it and make a new video. I have sold quite a few drawing packages of this engine, and I realize that not everyone will use the same carburetor as I did. I will post detail drawings of these three throttle parts, which were not in the original drawing package.


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## Brian Rupnow (Apr 2, 2021)

Here we have the throttle lever mounting bracket, which picks up two of the bolts used to hold the cylinder in place.


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## Brian Rupnow (Apr 2, 2021)

The throttle lever itself---


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## Brian Rupnow (Apr 2, 2021)

And finally, the throttle link which runs from the throttle lever over to the carburetor.


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## johnmcc69 (Apr 2, 2021)

A real nice job on this one Brian, I think the paint turned out really nice!

 Great work!

 John


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## Brian Rupnow (Apr 2, 2021)

John--The painted engines do look nice.---And every time I touch the damned things the paint gets scraped, nicked, or flakes off. I think that if I was really honest about painted engines, I would only recommend powder coating. Powder painted parts are almost bulletproof. Spray on enamels simply don't stand up to even minor abuse.


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## Tim Wescott (Apr 2, 2021)

A two-part epoxy or urethane finish might do.

I think there's even a rattle-can epoxy that you can get.  I only saw it on a model airplane forum, so I can't remember whether you do something special to activate it, or if it gets mixed when you buy it.  At any rate, once it's activated you have 20 hours or so to finish the job, then it hardens in the can.

If you want to know, I'll ask around for you.


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## Jbern (Apr 2, 2021)

Brian, really nice looking engine, great work. I would love to build it, how can I purchase the blue prints?


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## IC-man (Apr 3, 2021)

Hi Brian,
I too would like to have purchase  details of your plans for this engine.


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## Tim1974 (Apr 3, 2021)

Have you tried that hi temp paint that you bake in oven for a while? I used some years ago and was impressed


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## Brian Rupnow (Apr 3, 2021)

JBern-I sell the complete drawing package for $25 Canadian funds. There are 50 individual drawings. Go to Paypal and pay $25 Canadian to [email protected]   Paypal will contact me, then I send a .zip file of pdf drawings to you.---Brian


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## Brian Rupnow (Apr 3, 2021)

So, we're all finished up here. This is the final video. The engine runs very well and has been a very nice build. Good luck to all of you who have purchased a set of plans. I may take the rest of the summer off now, as I have developed quite bad carpal tunnel syndrome in my hands, so I want to stay out of the machine shop for an extended period of time until it clears up.---Brian Rupnow


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## CFLBob (Apr 3, 2021)

Brian - if I may ask - any idea what caused your carpal tunnel problems? 

The place I retired from had mandatory ergonomics training once a year and while they went beyond the usual keyboard things the vast majority of the ergonomics classes talk about, the emphasis was on the keyboard.  They talked about it from using wire cutters all day and programming in rest breaks to stretch.  In real life (not work) though, the only two people I know who have had carpal tunnel surgery were both on a cane and it was from bending their wrist backward too much. 

It doesn't seem like turning the wheels on the mill or lathe would lead to CTS.


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## Brian Rupnow (Apr 3, 2021)

I've had carpal tunnel problems in the past, and it is affected by how much you are moving and flexing your hands. I used to build hot-rods basically from scratch, and as in machining there is a tremendous amount of flexing and use of the hands. Some people get it, some don't. I know that when I had it bad about 15 years ago it was bad enough that I was offered corrective surgery. I declined to have the surgery, and after about 3 months of relative "rest" it went away. I expect that with a couple of months rest that it will go away this time as well.


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## CFLBob (Apr 3, 2021)

FWIW, I started to suspect a genetic link a while ago: some folks will get it much easier than others.  

I get tennis elbow regularly.  There are exercises that reduce it and prevent it (physical therapists give you these), and naturally, I get busy and don't remember to do them.  It's just another kind of tendinitis, in a different place.


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## fvd (Apr 4, 2021)

For what it's worth: in 1990 or so I had quite some pain in my right arm, I think due to too much playing with the computer mouse: a myriad of small movements of the hand to steer the mouse to the right pixel. One evening I did some heavy hand sawing of oak wood with the -for me- astonishing result that all the pain was mostly gone. Maybe this strange fenomenon (small pixel movements against heavy sawing) can help you with your carpal tunnel problems. Have a nice day. F. van Dijk


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## Charles Lamont (Apr 4, 2021)

That sounds most satisfactory on tick-over. What happens when you open it up?


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## cheepo45 (Apr 4, 2021)

I had my right carpal tunnel surgery when i was 35 (after working as a dealership mechanic for 16 years - don't use your hands for hammers!).
My left wrist was done at 60.
It was easy surgery and now both are fine.
 Scott


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## Brian Rupnow (Apr 4, 2021)

Charles--That is not "tick over". It's way faster than I'm happy with. Ultimately I want to play with the ignition timing and the carburetor settings  and get it to idle at about 2/3 of what you see in that video.


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## Steamchick (Apr 5, 2021)

Brian Rupnow said:


> So, we're all finished up here. This is the final video. ---Brian Rupnow



Hi Brian, having had the same carpal tunnel problem - from the computer mouse and wrong sitting position back in the 1980s, when the mouse first became available (The upside-down roller-ball on a wire!). It does take a few months to recover, so enjoy doing everything else, except playing with the mouse!
On the model, I just love it! You are well worth reading and watching every day of the week. - Pity they don't put you on TV and give you the loads of money you deserve. I must order some plans.
Thankyou for your presentation from start to finish.
K2


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## Steamchick (Apr 5, 2021)

Before I pay for plans, can you check the postage to the UK so I can add that? - Thanks.
K2


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## Brian Rupnow (Apr 5, 2021)

Steamchick--I email the plans to you in a .zip file. There are no costs involved other than what you pay me for the plans.---Brian


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## Brian Rupnow (Apr 5, 2021)

THIS POST HAS BEEN TEMPORARILY REMOVED UNTIL I GET IT FIGURED OUT A BIT MORE.--APRIL 06-2021


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## Steamchick (Apr 6, 2021)

Hi Brian, to accommodate the compromise between smooth low power at low revs and good high power at high revs most modern engines have Inlet can advance mechanisms. Obviously easy with a twin can engine, and too difficult with yours, but (like Triumph motorcycles in the late 1950s and early 1960s) different cam lifts and timing are quite common for engines needing to do different tasks. I agree advancing your cam 1 tooth is a very simple improvement to overcome the inlet blow-back issue you have detected. 
How did you determine the valve lift profile and valve timing in the first place? Did you model it on CAD? Maybe a different cam-follower profile can change system action from the inlet cam when you know better what you want? (A colleague who raced cars was always playing with follower profiles as they have a big effect on the lift from the cam: Triumph Motorcycles used a dozen or so different radii on their cam-followers, depending on the "tuning" of the bike).
Interesting stuff!
K2


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## Charles Lamont (Apr 6, 2021)

Brian Rupnow said:


> T When the engine is running at a fast idle, as seen in the videos, I can feel definite blasts of air coming out of the carburetor as the engine runs. What does this tell me??--It tells me that the cam timing is off, and that the intake valve is staying open too long during the power stroke. So--We get ignition, the burning fuel mix expands rapidly as it is ignited, and for an instant before the piston moves downward on the power stroke the intake valve is still open for a fraction of a second, letting compression escape thru the carburetor throat.


I think there may be a flaw in your argument. The inlet may be closing a bit late in the *compression* stroke, but if it were still open at the point of ignition, then there would not have been any compression.

On the other hand, if the inlet opens too early in the later part of the exhaust stroke, you may have too much overlap, and be blowing some exhaust out of the inlet.

Early events would tend to favour higher speeds, late ones lower.


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## jack620 (Apr 6, 2021)

Nice work Brian. I hope your carpel tunnel problem subsides after a rest.


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## Brian Rupnow (Apr 7, 2021)

I reset the cam timing by retarding the action of the cam by about 4 to 5 degrees. That made a tremendous difference to the way the engine idled and responded to the throttle being opened.


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## oldengineguy (Apr 8, 2021)

Brian: Did you retard the camshaft or just the inlet cam? Is that crank degrees or camshaft degrees? Would you post a final open-close diagram of the timing. This may be the cure for my poor running  Panther Pup variation. Thanks  Colin


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## Brian Rupnow (Apr 8, 2021)

Colin--since both cams are attached to the same shaft, any change I made influenced both cams. What I actually did was retard the cam-shaft, which retarded the two cams attached to it.---Brian


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## oldengineguy (Apr 8, 2021)

Brian: I wondered if you had moved the inlet only as the cams are held on the shaft with set screws . That is if  I've read the drawings  correctly. Colin


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## Brian Rupnow (Apr 8, 2021)

Colin--I didn't move the inlet only. To get at the cams and set screws, you have to completely disassemble the engine. I set the intake and exhaust cam lobes up to have 98 degrees of separation and they stayed that way. The first time I assembled the engine, I had the two cams 180 degrees out of phase with each other (Don't know how I managed that), and the engine wouldn't run. I completely disassembled the engine, removed the camshaft, and reset the cams the way they should be, then reassembled it and it ran, albeit very damned fast and with no throttle response. I decided that the cam timing was more or less correct, but based on air puffing out the carburetor while the engine was running, I deduced that the cam timing needed to be retarded a bit.--that was easy to do---I just set the crankshaft in the correct position rotationally, removed the gear cover, loosened off the set screws on the crankshaft gear, and turned the crankshaft gear by hand until I seen that the exhaust was starting to open, then locked up and reassembled everything.---Brian


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## Brian Rupnow (Apr 9, 2021)




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## lathe nut (Apr 9, 2021)

Brian you do such good work and always looks nice also, sure are glad to see your post knowing that we are in for a treat, thanks again for sharing with us, Joe


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## Tim Wescott (Apr 9, 2021)

Brian Rupnow said:


> I just set the crankshaft in the correct position rotationally, removed the gear cover, loosened off the set screws on the crankshaft gear, and turned the crankshaft gear by hand until I seen that the exhaust was starting to open, then locked up and reassembled everything.---Brian



Wait -- all the hot rod engine assembly instructions I've seen say to just line up the witness marks on the cam gear and crankshaft gear.

Now I'm confused


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## Brian Rupnow (Apr 9, 2021)

I have been asked about gaskets on this engine. There is a gasket 0.030" thick between the bottom of the cylinder and the crankcase. The head gasket is 0.030" thick. There is a gasket 0.015" thick between the two sides of the crankcase. These are simply standard utility grade gaskets, cut from rolls of automotive gasket material. Same material as would be used for fuel pumps, waterpumps, etcetera. I do not use a special grade of head gasket material anywhere on the engine.


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## Jbern (Apr 9, 2021)

Brian....What did you use for a piston ring? Cast iron or O-ring?


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## Brian Rupnow (Apr 9, 2021)

I used a 1" o.d. x 1/16" cross section Viton o-ring.


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## IC-man (Apr 10, 2021)

Brian Rupnow said:


>


I thought intake followed exhaust.


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## Brian Rupnow (Apr 10, 2021)

Ice man--You were right--I have fixed it.---Brian


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## Brian Rupnow (Apr 13, 2021)

Today I made an "add on" for the gear cover. It's not so much a safety thing as a noise reducer. Yes, if you were careless enough to stick your finger in there while the engine was running, it would probably give you a very quick manicure. The spur gears which drive the camshaft are noisy little devils. The 0.100" thick piece of aluminum I added to the gear case will fill up the gap and cut down on the noise. I find it almost impossible to add on a piece like this without screwing up the paint on the part I'm adding to, so it was simpler to give it a five minute soak in laquer thinners, wipe off any remaining paint, and then repaint the entire thing.


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## Brian Rupnow (Apr 19, 2021)

Now we are going to try something a little different. The engine runs well as is, with a Viton o-ring on it, but I'm bored doing nothing, so now we are going to see how it runs with cast iron rings. If you are one of the people who purchased plans for this engine, fear not--the new piston drawing and anything relevant to it will be posted here. This morning I purchased a foot of 1 1/4" diameter grey cast iron from my local vendor for $40.(He didn't have any 1" cast.) That seems like a lot, but then there should be enough material there to build about 10 pistons. I have ordered a set of two compression rings from Debolt  The price was shocking, at $52 Canadian funds, but that is $10 American for each of the rings and $20 American for shipping. The top of the new piston will be about 0.080" taller from the wrist pin, to give the engine a bit more compression. I won't be buying any more cast iron rings in future, but will be making my own. I am not going to start machining the new piston until I have the rings here.---Brian


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## Tim Wescott (Apr 19, 2021)

I'll be interested in your experiences when you get around to making rings.  There seems to be a lot of ways to succeed, but a lot more ways to screw it up!  Study is warranted before actually launching into the effort to do the job.


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## CFLBob (Apr 19, 2021)

When you said you bought 1-1/4" grey cast iron bar, I assumed that was to make the rings, rather than the piston.  Especially with shipping costing the same as the two rings.  

Isn't cast iron the material for making rings?


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## Brian Rupnow (Apr 19, 2021)

Yes bob, cast iron is the material for rings. It is also great for pistons in slow running engines. The material I bought will make either rings or pistons. I can not rework the existing aluminum piston to accept cast iron rings.


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## jack620 (Apr 19, 2021)

Brian Rupnow said:


> that is $10 American for each of the rings and $20 American for shipping.



Twenty greenback to send a few piston rings from the US to Canada? Wow. I don't feel so bad about the postage from the US to Oz now.


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## johnmcc69 (Apr 19, 2021)

With all this debate about rings lately, I'll be watching intently.
 Nonetheless, it's a great little engine Brian.

 I can't wait to see what you come up with next.

 John


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## Charles Lamont (Apr 20, 2021)

AFAIK it is usual to use a better grade than soft grey iron for piston rings - such as "17 ton" or "Mehanite". I am not sure, but I think centrifugally cast bar is usually this sort of quality anyway.


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## Steamchick (Apr 20, 2021)

Thanks Charles, I didn't know that. Back in the late 1980s I went to Hepworth and Grandage in Sunderland to see ring manufacture. I recall: 
Rings were cast in trees.. about 6 around a central feeder core and a dozen layers so dozens of rings come from each sand casting. But I don't  remember much about the cast iron. Some pig iron and a lot of recycled scrap, incuding all the swarf. No iron wasted! Maybe there was something to change it from grey to mehanite? Needs a metallurgist to teach us all.
When broken off the core the circles were ground on top and bottom faces, then clamped into tubes of dozens of rings. 
The tubes were bored, reassembled for machining outers, split, then bores finally ground while clamped in the compressed state, then reset on mandrels  for OD grinding while compressed. Finally honed in special machines to develop a curve on the face. On models we call this running-in. I can't  remember heat treatment. 
K2


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## Tim Wescott (Apr 20, 2021)

"Meehanite" is a trademark; if a foundry sells it, that means they're licensed to do so (and they're audited for quality by the Meehanite company).  And apparently there's more than one kind of Meehanite -- gray, gray flake, and nodular.

From my studies, making it right involves a little bit of everything: getting the right mix, getting the casting process right, & possibly heat treating (certainly heat treating in the case of nodular cast).

I bet Machinery's Handbook lists the grades -- if I were good, I'd go look myself.






						Meehanite - Wikipedia
					






					en.wikipedia.org


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## Steamchick (Apr 20, 2021)

I am fairly sure (as memory isn't  100% reliable) that H & G inoculated the iron before pouring. But in a different foundry I saw this used for the production of Spheroidal graphite iron. Perhaps this is just unlicensed Mehanite? Or the copy write / patent has expired?
K2


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## Brian Rupnow (Apr 20, 2021)

Fine grain grey cast iron is suitable for rings. Mehanite is suitable for rings.


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## Tim Wescott (Apr 20, 2021)

@Steamchick : I got the impression from the Wikipedia article that Meehanite is a trade name that your foundry can apply if you're licensed.  So you could make exactly the same thing, but you couldn't _say_ so.  It gets complicated, but probably even "just like Meehanite" would be an infringement, where a data sheet that exactly matches one of the flavors of Meehanite wouldn't.


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## Rdean33422 (Apr 21, 2021)

Brian I want to thank you for including the make and model carburetor that you used on this build.  I had built a similar size engine and was having problems with the carbs I had been using.  The Traxxas 4033 has solved all my problems as it is very easy to adjust and very predictable.

I have added a video to my original thread in the "Finished Projects" section of the engine running now.

Thank you
Ray


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## awake (Apr 21, 2021)

Steamchick said:


> I am fairly sure (as memory isn't  100% reliable) that H & G inoculated the iron before pouring. But in a different foundry I saw this used for the production of Spheroidal graphite iron. Perhaps this is just unlicensed Mehanite? Or the copy write / patent has expired?
> K2


l am completely out of my depth on this, so this comment may be totally useless ... but hey, that has never stopped me before!

A YouTuber named LuckyGen routinely does cast iron; he talks about having to add ferrosilicone to the melt to get the desired results (e.g., not chilled). So maybe that is the sort of innoculation involved?


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## Steamchick (Apr 22, 2021)

Andy, I am even less knowledgeable than you! But enjoying learning from the group discussion. I am not about to cast iron, but now know I need fine-grained cast iron, not just "any old scrap" from my bin before attempting to make rings. I here a 3/4 cc diesel that needs a new cylinder & piston (no rings). The last cast iron piston I made had good compression, but not for long! Then I found the cylinder cracked... 
Thanks, K2


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## Brian Rupnow (May 4, 2021)

So, here we are. Two rings from Debolt. What did they cost?-Well, by the time I bought them, paid for the shipping, paid the tax, and paid the difference between USA and Canadian dollar, I spent $50.00. I'm not going to say that it's anyone's "fault". I used to be able to get a complete set of rings for a V8 car for that money.  They don't look different in any way from the rings I've been making at home in the last couple of weeks. If anybody is shaking their head about the toolpost grinder and heat treat furnace I've just bought, think about that for a minute. There is probably less than 50 cents worth of material in either ring. I hope to never ever have to buy rings again. I hope these rings work okay, anything else I have ever bought from Debolt worked just fine. I'm going to make a new piston for this engine to put the Debolt rings on, and Jeez, I hope they work okay.----Brian


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## Johan Maritz (May 5, 2021)

I'm following Brian, I'm nearing the dreaded ring making process, and it seems daunting. Must admit i learned a lot  already.


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## dsage (May 5, 2021)

If I'm not mistaken you ran your home made rings - possibly not round - for some period of time driven by an electric motor. It's possible that now your cylinder is not round so your results with the (Presumably perfect) new rings may be questionable. Honing the cylinder will not  make it round and will remove some material so it won't be 1" diameter any more either.
I would suggest you don't "run in" those rings in an attempt to gain compression. If everything is proper you should have good compression right off the bat. If not put those expensive rings aside for a new venture.
You have experience with full sized engines. How many of those have you had to "run in" to get them to run??
I hope you are successful. You've been through heck with this experiment.
Just saying.


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## Brian Rupnow (May 6, 2021)

Alright---Here we go again!!! This is a brand new cast iron piston, hot off the lathe. The two rings on it are the two I bought from Debolt. The piston is 0.998" diameter and is a good sliding fit into the cylinder. Both rings were placed squarely into the cylinder and the ring gap is 0.004". I made a mask 0.9" diameter to fit inside the compressed rings and 0.950" outer diameter to set squarely into a ring in the cylinder. One ring showed no visible light between the outside diameter of the ring and the piston wall. With the other ring I found it very hard to tell. The only thing I did to the rings was use a points file to break the sharp inner corner where the split was, so it wouldn't scratch the piston when I installed the rings. Both rings measured "about" 1/16" thick. My 1/16" parting off tool is 0.062" wide, but for some strange reason it cuts about .055" wide on a direct plunge cut into cast iron. I kept taking 0.055" deep plunge cuts and kept trying to fit the ring into the groove in the piston. By the time I had it wide enough to let the ring set into the groove all the way to the bottom of the groove, I had cut each ring groove  "about" 0.065" wide. I coated both rings and piston with 30 weight motor oil and had no problems getting the rings onto the piston---although I turn rather blue from holding my breath while I do it. I have a "jig" with a 1" diameter reamed hole in it and a 15 degree tapered lead into it.--The piston with rings on it slides quite nicely into the jig, thanks to the generous lead in taper which compresses the rings for me. If the piston fits into me jig okay, then it is going to fit into my cylinder okay.


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## Brian Rupnow (May 6, 2021)

dsage--Interesting that you should ask that about full size engines. I never had to "run in" any of my full size V8 engines, but they did crank hard the first time they were started. ---However----I had an uncle who lived in Deep River, Ontario. He knew I was a car nut, so when I was about 15 he took me over to meet a friend of his who raced stock cars at a local track. This friend had just finished a rebuild on the V8 engine in his stock car, it was race night, and the engine was so stiff it wouldn't crank over with the starter. He got a rope, tied it to the front bumper of the stock car and to the back of another stock car guys truck. He told the other guy "Keep it in high gear with the clutch in until I get up to about 40 miles an hour out on the black top, and then let the clutch out---we'll get his thing broke loose for tonight's race!!" Of course I asked to go along for the ride, and the stock car guy seen that I was just loving this, so he let me ride with him. At 40 miles an hour the guy in the stock car let out the clutch. The engine was so tight that the rear tires both screeched on the pavement, but then the engine broke loose and started and all Hell broke loose!! I swear to God, there was white smoke, black smoke, grass snakes and baby apes coming out of that stock car engine. It ran, and they made the race that night. I was so excited that I almost peed my pants!!!


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## jack620 (May 6, 2021)

Brian Rupnow said:


> This friend had just finished a rebuild on the V8 engine in his stock car, it was race night, and the engine was so stiff it wouldn't crank over with the starter.



This is how the F1 mechanics solve that problem:

_"Due to the very tight bearing and piston-to-bore clearances on an F1 engine, the engine cannot be started from cold and must be brought up to the recommended start up temperature in order to avoid damage to the moving parts. The recommended start up temperature for the engines varies according the brand but is around 70-80 degree Celsius. The engine is warmed using a remote electric pump to circulate hot coolant through the coolant passages prior to start up. The pump is a purposely built unit mounted on a trolley for ease of use in the pit garage, and connects to the engine via plug in hose connections.

Hot coolant is used to warm the engine itself, but the engine oil also needs to be heated to operating temperature, and this is done outside the engine. The oil is warmed using a bespoke remote warning device that ensures the oil is warmed up evenly to the required operating temperature."_


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## Brian Rupnow (May 6, 2021)

Jack--It's a great story, but it was 50 years ago.--A bit of interesting fact though--I worked one winter in Kapuskasing in northern Ontario. The company was a huge paper mill, with a very large parking lot for employees. Each parking spot had an electrical outlet so people could plug in their automobile engine heaters to keep the engines from freezing solid during an 8 hour shift. The big diesel trucks that distributed the companies newsprint had quick disconnect coupling on the radiator hoses, and if they were left overnight the quick disconnect hoses would be connected to a heated supply of water and anti-freeze that was heated inside the factory and circulated thru the truck engines so they wouldn't freeze solid.


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## olympic (May 7, 2021)

Ah, northern Ontario!

Years ago I stayed in a motel in Dryden and plugged my van into one of their outlets. Come morning and  -39 degrees (choose either temperature scale) I found that the outlet wasn't working when my 350 cu. in. V8 groaned once--and actually started.

Couldn't have been very good for the engine, though....


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## Tim1974 (May 7, 2021)

Ok boys rings every ring has to bed or run in it’s a fact of life so we can talk all day or make rings it’s easy and really not a lot of time just have fun


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## johwen (May 8, 2021)

How we bedded in rings in the early days of motoring on new cars was simple. We drove the cars at full throttle fully loaded in top gear for twenty yards backed off let it slow and the repeated 4 or 5 times. we had no oil burners or cars lacking power This loaded the ring against the bore with full pressure behind the rings.
John S. Auto engineer.


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## Brian Rupnow (May 9, 2021)

Today I removed the original piston with a Viton ring, and replaced it with the new piston which has two cast iron rings on it from Debolt. I got really lucky---I thought I was going to have to split the crankcase halves to replace the piston but I didn't have to. With the cylinder removed, there was just enough access to reach up inside the piston and loosen the set screw which held the wrist pin in place. Then it was a simple matter to drift out the wrist pin and put the new piston back in it's place. Getting the rings compressed enough to let the piston slide up into the cylinder wasn't really that bad--mostly fingernail work holding the rings into the grooves deep enough for the piston to slide in. There is one bolt head that is actually inside the combustion chamber ---it's one of the socket head capscrews  which holds the rocker arm tower in place on the cylinder head. While I had the cylinder head off I took that bolt out, mixed up a batch of J.B.Weld and coated the shcs with it, then reinserted the shcs. I did this so that as the bolt was tightened into the thread in the cylinder head, the J.B.Weld would squeeze out of the threads and fill the area between the head of the bolt and the counterbore just to make absolutely certain that no compression was leaking out there. I'll wait 24 hours now and then hopefully run the engine tomorrow. While I had the cylinder off the engine I used a 3 stone brake hone to cross-hatch the bore. This will help retain a little oil for ring lubrication and help the new rings to "bed in" . To be honest, I can turn the engine over easily by hand right now and I'm not feeling any compression, but if I can get the engine to run tomorrow it should develop a lot more compression as the rings "bed in".


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## dsage (May 9, 2021)

Fingers crossed.


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## Brian Rupnow (May 9, 2021)

I could feel a hint of compression when turning the engine over by hand, but it's a new engine and still a bit stiff, so I didn't know whether I was really feeling some compression or just hopefully imagining it.---So---I pulled out the sparkplug and gave it a couple of squirts of #30 motor oil down the sparkplug hole, then reinstalled the sparkplug. It immediately had a lot of compression. I certainly hope that I can get the engine to fire and run tomorrow. I have the feeling that if it fires and runs that the new rings will "bed in" and seal properly.


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## Brian Rupnow (Jun 11, 2021)

This is a video I made today, 11-june-2021 of my vertical i.c. engine 2021. I have been trying to make a set of  cast iron rings for the piston, and as part of that I built a new cylinder and new piston to accept cast iron rings, but ultimately I was not successful. Finally I decided that I should put this engine back together, so I enlarged the top ring groove to .093" wide x 0.058" deep and put a Viton ring on it. This engine can now go up on the shelf with all of my other engines. I am still after cast iron rings that actually work, but will be trying them out on a different engine that is a lot simpler to take apart and access the piston.----Brian


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## Steamchick (Jun 12, 2021)

Brian, I could watch you work all day... the results are simply splendid! Well done on a nice little engine!
K2


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