# Inspiration for new air motor



## Brian Rupnow (Apr 1, 2018)

I really, really, don't want to start another build right now. However--I have been researching all of the many different flamelicker engines, and ran across the Bengs unit. My God--It's awesome!! I wouldn't want to build a flamelicker engine, as I now have finished the Poppin by Dr. Senft, and a Stirling engine which was 75%Moriya fan and 25% me. I have I.C. engines out the ying yang. and a goodly number of air/steam engines. I really like the style of this engine, and may design a single acting air motor based on this.





[ame]https://www.youtube.com/watch?v=0G4OuBVb7NY&feature=youtu.be[/ame]


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## Brian Rupnow (Apr 1, 2018)

I find it strange that the rocker arm isn't set at a 1:1 ratio. It looks like the distance from the piston rod to the pivot is twice as long as the distance from the pivot to the connecting rod. I'm trying to wrap my head around that. I don't think it changes the number of flywheel revolutions to cylinder strokes. I think it just means that you can get away with a shorter throw on the crankshaft.


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## TonyM (Apr 1, 2018)

The ratio looks about 2:1 so maybe half the effort to turn the flywheel.


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## Barnbikes (Apr 1, 2018)

I could see you building this one.
[ame="https://www.youtube.com/watch?v=YZMBFG9Eyzw&t=53s"]https://www.youtube.com/watch?v=YZMBFG9Eyzw&t=53s[/ame]


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## Brian Rupnow (Apr 1, 2018)

I have the engine all designed---in my head. The only thing I'm not sure of is the valve mechanism. Since it will only be a single acting engine, it doesn't really require a sliding admission valve like you would find on a double acting cylinder. Probably a simpler valve driven by an elliptical cam through a couple of bell crank mechanisms would work. I have an old Chuck Fellows single acting engine that I converted from it's original design to operate with a valve like this. I'll have to see if I still have the drawings of my design changes to Chucks original valve mechanism. Other than the double acting twin Stewart engine I built this winter, it's been a long time since I messed around with air/steam engines.


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## Brian Rupnow (Apr 1, 2018)

Ah Rats!!! I can't find the files I need. I thought I had them on a disc, but after a massive disc hunt I can't find them. I do have the original files of Chucks hit and miss engine, but not the changes I made to the valve system.--However, it's not a major issue. I have the engine here on my shelf and I can pull it apart and reverse engineer it.


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## Brian Rupnow (Apr 2, 2018)

Okay---We're good!! I took the old single acting engine down of the shelf and did a little reverse engineering. Now I know exactly how the valve for a single acting engine works. (I had forgotten). This is the valve my new creation is going to use. It is a very versatile valve that can be mounted any number of different ways.


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## Brian Rupnow (Apr 2, 2018)

Where do you start with something like this? Well in my case, I happen to have a pair of 4" flywheel rings that at one time were mounted on my Kerzel engine. They didn't improve the hit and miss action of the Kerzel, so they were saved for a future project. This may be it. Second consideration is ratio and proportion. If you look at a side view of the flame-eater engine I am copying the style of, you will see that there is a ratio between the outer diameter of the flywheels, the outer diameter of the cylinder, and the length of the cylinder. There is also a relationship between the center of the flywheels and the centerline of the cylinder, both vertically and horizontally. This is somewhat subjective. And of course we know that the flywheels have to be placed far enough from the center of the cylinder that they won't rub on it.--So, for now we place them where they won't hit the cylinder as they revolve. That's what is involved in the "starting point" of a layout .


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## Mechanicboy (Apr 2, 2018)

Brian Rupnow said:


> I find it strange that the rocker arm isn't set at a 1:1 ratio. It looks like the distance from the piston rod to the pivot is twice as long as the distance from the pivot to the connecting rod. I'm trying to wrap my head around that. I don't think it changes the number of flywheel revolutions to cylinder strokes. I think it just means that you can get away with a shorter throw on the crankshaft.



With large piston stroke + diameter transfered power via rocker arm who are pivoted in 2:1 ratio will give larger torque in crankshaft.


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## Brian Rupnow (Apr 2, 2018)

Of course we are going to have to have a couple of supports to hold this engine up off the tabletop. This calls for milling a couple of 1/2" wide slots in the bottom of the cylinder and making up a pair of stands that will bolt to the cylinder. Right now the supports look kind of long and skinny, but the reason for that is to let the ends of the mount stick out far enough past the outside of the flywheel that I can reach down beside the flywheel with my screwdriver and put a #8 woodscrew through each of the four holes to mount this puppy to my workbench.--Don't want it to walk away on me when it's running.


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## Brian Rupnow (Apr 2, 2018)

We need a piston. There's a lot going on with a piston. The cylinder bore is .875", so we want our piston to be a "precision sliding fit" into the bore. A good enough fit that it won't fall through under gravity, but will go through with a gentle push with your finger. We don't want our piston to "cock sideways" in the cylinder, so we make it  "a bit" longer than the diameter. There isn't going to be any rings on this piston, but we need two shallow grooves around it for oil retention to help prevent air from passing around it. We want the hole for the wrist pin to be less than halfway from the closed end of the piston. This again is a measure to prevent "cocking sideways" in the cylinder. we need a slot wide enough for the connecting rod to fit into, and we want to releave a lot of material from the open end of the cylinder to prevent the con-rod hitting the inside of the skirt when it is at it's most extreme angle.


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## Brian Rupnow (Apr 2, 2018)

What can I say about flywheels? The easiest flywheels to make are from aluminum. But--aluminum just isn't heavy enough to make a good flywheel. However, a two piece flywheel with an aluminum center and a steel outer rim work really, really well. For the artistic among us the holes in the center can be just about any shape, even the creation of curved or straight spokes is possible. Just a note here in an area I've been burned on before. Make the hub diameter large enough that you have at least 3/16" of material between the centerhole and the outside of the hub, or your set screws are going to strip out. If you have a keyway, then make your hubs large enough in diameter to allow at least 3/16" between the outer limit of the keyway and the outside of the hub, or again, your set screws are going to strip out. I like to put two set-screws in each flywheel, 90 degrees apart. If I have a keyway, then one set-screw sets over the keyway and the second at 90 degrees from it. And finally--although it isn't really critical, flywheels look a lot better with the "spoke area" relieved about 1/3 of the flywheels thickness on each side as I have shown.


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## Brian Rupnow (Apr 2, 2018)

Well sir!!! I'm surprised right outa my pants. I have input the geometry based on a 2:1 ratio in the pivot lever, and it works. The crank "throw" is 1/2", but because of the 2:1 ratio in the pivot lever, the piston actually travels 2". Now I have to make this. I will try and put up an animation.


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## Brian Rupnow (Apr 2, 2018)

This is going to be amazing.
[ame]https://www.youtube.com/watch?v=SgS8hpX75B4&feature=youtu.be[/ame]


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## kiwi2 (Apr 3, 2018)

Hi Brian,
               It may be worth while designing the steel rim of the flywheel to be consistent with the dimensions of say schedule 80 pipe. 3 1/2" schedule 80 steel pipe has an OD of 4" and a wall thickness of 0.318" while 4" schedule 80 pipe has an OD of 4.5" and a wall thickness of 0.337". The 4" material is likely to be more readily available than the 3 1/2".
Regards,
Alan C.


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## Brian Rupnow (Apr 3, 2018)

kiwi2 said:


> Hi Brian,
> It may be worth while designing the steel rim of the flywheel to be consistent with the dimensions of say schedule 80 pipe. 3 1/2" schedule 80 steel pipe has an OD of 4" and a wall thickness of 0.318" while 4" schedule 80 pipe has an OD of 4.5" and a wall thickness of 0.337". The 4" material is likely to be more readily available than the 3 1/2".
> Regards,
> Alan C.


Have a close look at post #8.--I already have those outer flywheel rings left over from a different project.


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## Brian Rupnow (Apr 3, 2018)

I'm all ready to go on this thing, except for the valve which operates off a cam on the crankshaft. I have a terrible time with the valving on these things because I don't do many of them. I have the valving on normal double acting cylinders sussed out pretty good, but these single acting ones make me a bit crazy.


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## Brian Rupnow (Apr 3, 2018)

This animation shows the valve and valve mechanism in place and operating. I believe I have found good mechanical solutions to everything. Nothing "crashes" during a 360 degree rotation. The nearside flywheel is "hidden" in order to clearly see all of the parts moving. The only part I am unsure of is the valve. I re-used the eccentric cam and the valve body and valve slider from a running engine that I have, but due to the strangeness of this engine, valve events are not occurring when they should, and I don't have enough experience with valving to correct it.  If anyone with experience wishes to step up and help me with the valving, the engine will be built. In return for that help I will give them a complete set of plans for this engine. If not, it will just remain an interesting design exercise.---Brian
[ame]https://www.youtube.com/watch?v=FhpR4OAYmnQ&feature=youtu.be[/ame]


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## johnmcc69 (Apr 3, 2018)

It seems your cam is not rotating at the same speed as the crankshaft in your animation.

 John


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## Brian Rupnow (Apr 3, 2018)

I feel a bit foolish even having to ask. I am supposed to be "SuperDesigner" and know all this stuff. I know what I want to happen, and I know when I want it to happen. I'm just not sure how to get there. Really, about the only variable is the offset of the eccentric and the length of the link directly above the valve itself. The rocker is equal length from the pivot shaft to the center of the crankshaft and to the center of the valve when taken in a horizontal plane. That exact same eccentric, valve, and valve body works fine on the Chuck Fellows engine that I built about 10 years ago, then modified it from Chucks valve design to mine. I am moving all of the inter-related parts with my Solidworks, but I'm not getting the same positional results with this engine.


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## Brian Rupnow (Apr 3, 2018)

johnmcc69--the cam is rotating at the same speed as the crankshaft, but you have to watch it on Youtube at full screen to see it.


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## Brian Rupnow (Apr 3, 2018)

I've just realized that my valve sequence may seem a bit funky because with the pivot in between the crankshaft and the actual valve, the valve action is reversed from what the original motor was.  Now I have to try and decide what that information actually means to me. Last night I printed out five pages of valve positions from the original motor, to determine where the valve was when the piston was at top dead center, bottom dead center, halfway thru its stroke going up and coming down, and what things looks like at 45 degrees past dead center travelling counter clockwise. I'm 99% certain that if the cam, valve, and valve body worked on one single acting engine, it should work on another single acting engine, even though the piston stroke may change from on e engine to the next.


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## Brian Rupnow (Apr 3, 2018)

I'm pretty sure I have the valve sorted out, thanks to some help from Jason. Now if I get really, really, really bored this summer, I have something to work on.


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## Brian Rupnow (Apr 4, 2018)

Sometimes it is a bad idea to make too much of a change from whatever engine inspired you in the first place. I didn't like the look of the feet that I had on the model, so I changed them to be more or less the same as the flame-eater engine in the first post of this thread.


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## Brian Rupnow (Apr 4, 2018)

I have a theory on engine building that goes like this. Take the awfullest, most miserable part on the whole job and do it first. If you can do it successfully, then anything that comes after will be easy. The block that holds the crankshaft bearings and the pivot shaft is the hardest part on this engine. I rooted around in my box of aluminum and found a piece big enough to do what I wanted. This is kind of a trick, because you need a considerably larger piece to start with than what you finish with---especially if there are radii near the perimeter of the piece. You can't drill half a hole, so the stock needs to be large enough to leave about .100" beyond any holes that are drilled to give these radii. there are four holes to be drilled here. A 1" dia. hole on the right to give the radius I want. A reamed 3/16" hole in the upper left corner for the pivot shaft, a 3/8" hole below that to give another radius, and the center hole, bored to 0.906" for a bearing fit. You can actually see the bearing setting in there in the shot on the mill. I drilled that hole to 27/32" and bored it the rest of the way.


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## Brian Rupnow (Apr 4, 2018)

Some quality time with my friend the bandsaw yields a part that is starting to look like the drawing.


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## werowance (Apr 4, 2018)

I would like to see how you do the outside radi on the pivit pin holes.

will you file them to size or will you machine?


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## Brian Rupnow (Apr 4, 2018)

I have 3 choices, I can use milling machine-rotary table, or my big belt sander, or make a couple of filing buttons and use them. The Filing buttons are the least work with no danger of cutting too much.


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## werowance (Apr 5, 2018)

I remember the filing button trick from the universal joint build you did.  thanks for reminding me about that one.


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## Brian Rupnow (Apr 5, 2018)

This morning I cut the center out of the bearing support I made yesterday, and  to finish it up nice I've made up a pair of filing buttons.  These are made from 01 steel rod, cut to the finished diameter you want on the part you are going to file ,and have a hole in the center same size as the shaft you will be using. Then they are heated to red/orange and dropped into a can of oil. They are now harder than the devils horn, so a file won't cut them. You mount them as I have shown, and then use a file to cut the aluminum part, and the filing buttons keep your file from going where it shouldn't.


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## Brian Rupnow (Apr 5, 2018)

Now is that a beautiful thing, or is that a beautiful thing!! Using the filing buttons sure makes for a nice round pivot shaft boss. I keep making and saving filing buttons for applications like this. Much of the time if the radius is large I just use my stationary belt sander and "eyeball" it. I have a 3 jaw chuck permanently attached to my rotary table, so it's rather difficult to do radii on the rotary table.


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## Brian Rupnow (Apr 5, 2018)

I turned two pieces of aluminum to the correct width, i.d. and o.d. to become bearing caps. This used up two "short ends" out of my stock bin. If I do this right, when the caps are holding the ball bearings correctly, there won't be a visible gap between the caps and the main part they bolt to.


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## Brian Rupnow (Apr 5, 2018)

And now you know how I spent my day. Dang!! There's a lot of work in them bearing caps.


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## Brian Rupnow (Apr 6, 2018)

Today's work was this rather elegant little piece that looks a bit like a wishbone out of a metal chicken. Form follows function--the gap between the two arms is to allow room for the connecting rod big end to pass clearly when it rotates. There will be a second part to this linkage which runs in the opposite direction from the 3/16" steel shaft and picks up the eccentric cam movement.


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## werowance (Apr 6, 2018)

looking good,  question on the bearing caps.  when drilling off center of a circle like that, what do you do to keep the bit from walking?  do you use an end mill to start the hole downwards and switch to a drill when you have  a flat? or whats the trick to a drill like that?


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## Brian Rupnow (Apr 6, 2018)

I always use an end mill to cut just deep enough to have a flat spot to start  a drill/countersink. After I have "touched" the flat enough to make sure my drill doesn't "walk", then I drill the hole. Many people say you don't need to use a drill/countersink to start your holes, even on a flat surface, but I get much more consistent results by using one.---Brian


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## Brian Rupnow (Apr 6, 2018)

I had high hopes of getting the first assembly of my crankshaft completed today, but I just plain "ran out of gas". I bought the material, cut it to length drilled 3 of the four holes in the crankshaft webs--and that was all I had energy for. I like to do the initial assembly and Loctite it, then let it set for 24 hours before cutting the center out and adding the dowel pins. Ah well--tomorrow--tomorrow--


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## Brian Rupnow (Apr 7, 2018)

We have a crankshaft---at least a darn good start on one. I just got it assembled with Loctite. After it sets up for 24 hours I will dowel all the joints and then cut the center out.


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## Brian Rupnow (Apr 7, 2018)

Nothing says class like brass!! Con rod is finished other than a visit from the bling fairy.


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## Brian Rupnow (Apr 8, 2018)

Well, that takes care of most of the major linkages. Crankshaft has been drilled and dowelled. The link that goes over to the elliptical cam is a bit odd, so I may do it next.


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## Brian Rupnow (Apr 8, 2018)

This afternoon I made a start on the cylinder. A great big scaly old piece of cast iron, with a finish on it like a ponderosa pine. It was about 2 3/8" diameter and had came right from the foundry that cast it that size. I used a brazed carbide tool to bring it down to within about 0.010" of finished size, then changed to a HSS tool for the final cut to bring it down to 2", running about 400 rpm.  I don't want to take it out of the chuck, so I will move my tailstock back out of the way and rig my steady rest to support the end opposite the chuck while I drill/bore/ream the 7/8" hole in the center.


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## Ghosty (Apr 8, 2018)

Brian,
Some of the cast iron I have machined over the years were the same, hit with the ugly stick, and found to be some of the best machining after getting under the scale., 
Looking good, just following along.

Cheers
Andrew


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## Brian Rupnow (Apr 9, 2018)

HoooYahhh--it goes round and round and nothing crashes. There isn't a lot of clearance anywhere, but a miss is as good as a mile!!


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## Brian Rupnow (Apr 9, 2018)

I'm getting to the point where I have to be careful of what gets done next. The cylinder is still up in the lathe, and before I tear down the set-up I will put my steadyrest on the end opposite the chuck and drill/ream it to 7/8" diameter. Since this engine will have a ringless piston but still require a "very good" sliding fit, I will lap the piston into the cylinder. This requires that I hold the piston in the chuck, and with the lathe turning slowly I use either diamond paste or aluminum oxide 600 grit, and hold the cylinder by hand, slowly sliding it onto the piston in a back and forth movement. This is a "by feel" fit, and it's not uncommon for it to "grab". When it does, you want to be able to let go of the cylinder very quickly. I used this method on the two cycle engine I built, and it worked perfectly, but is more than a little scary. As you can see in the attached picture, there are three flats to be machined into the cylinder, but I won't put them on it until after the piston fitting is over with. I want to do that while the cylinder is a simple cylindrical shape, so nothing on it can grab my hands and wind me up in the lathe.


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## Brian Rupnow (Apr 10, 2018)

The cylinder has the steady rest on it to keep it from flopping around with so much "stick-out". The hole is being drilled in stages, first a 5/8" drill, then a 3/4" then a 27/32" drill, and after that I will bore it to 0.875".


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## Brian Rupnow (Apr 10, 2018)

So---We have a cylinder and a cylinder head. I didn't use the reamer at all. I drilled it out to 27/32" and finished up with a hefty brazed carbide boring tool. The finished bore as of now is 0.873". The best thing about this cylinder is that it was free. Nah, I actually paid for it on some other job and the 7" long piece of cast iron was a left over . Next up will be to machine a piston.


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## Brian Rupnow (Apr 10, 2018)

After honing the cylinder with my variable speed drill and a 3 stone brake hone, then lapping it with 600 grit aluminum oxide paste and one of my new laps, the bore is setting right on 0.874" (near as I am able to measure it with a telescoping bore gauge and a micrometer). I think that rather than lapping the piston into the cylinder, I will make an external lap and bring the piston down until it matches the cylinder bore.


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## Brian Rupnow (Apr 11, 2018)

This afternoon I made the piston. It's so new in this picture that it hasn't even had the tit machined off the end yet. Tomorrow I will decide exactly how I'm going to fit it to the cylinder, and will face it to the correct length, getting rid of the tit in the process.


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## Brian Rupnow (Apr 11, 2018)

I think I may have to go to larger flywheels. The flywheel input to the sliding piston is at a 1:2 mechanical disadvantage. That means that the flywheels need to be considerably larger than on a "normal" engine where the flywheel ratio to piston travel is a 1:1 ratio. I have looked at a number of videos of this engine as a flame-eater, and they all have larger flywheels. My original thoughts were to have a 4" o.d. flywheel. Now I'm thinking of larger diameters. A 4" nominal diameter pipe has an actual o.d. of 4.5" (dotted outline on drawing). I have to think on this for a bit, and as I have other parts of the build to complete, I have time to roll this idea around in my head a bit.


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## Brian Rupnow (Apr 12, 2018)

I had the four jaw chuck up on the lathe, and decided to see if there was anything on this engine which would require the four jaw. Sure enough, the elliptical can still had to be machined, so that's what I did this morning. You can see it setting in place on the crankshaft. Now I change back to the 3 jaw and fit the piston to the cylinder.


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## Brian Rupnow (Apr 12, 2018)

I have achieved an almost perfect fit between the piston and the cylinder. It doesn't show in the picture but the entire piston has taken on that uniform dull finish that comes from lapping. The piston will slowly fall thru the cylinder under the force of gravity, but if I put a hand over the bottom of the cylinder the piston stops. I have to go and keep an appointment now, but when I get back I will explain a bit more about how this was done.


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## Brian Rupnow (Apr 12, 2018)

Here's a little story on how I sized the piston to the cylinder. In shot one, you see the piston, a short piece of threaded rod with one end turned to fit into the piston where the con rod goes, and a hole in it for the wrist pin. The shaft laying in line has the end turned to fit inside the piston, with a shoulder on which the piston can set, and a 5/16-18 tapped hole in the end. The turn down at the other end of that piece of shaft is not needed.--it just happened to be there. In shot #2 the threaded rod is mounted in the piston. You can't see the wrist pin, but trust me--it's there. The retaining set-screws that hold the wrist pin in place are tightened down--I don't want the wrist pin to drift to one side and score the cylinder wall. Shot #3 shows the piston tightened onto the piece of shaft, with the piston skirt setting on the register. Shot #4 shows the shaft with piston mounted in the lathe chuck, and picture #5 shows the cylinder started on over the piston. The piston is coated with #600 aluminum oxide paste. The piston diameter has been turned to a diameter that just starts to fit into the cylinder, but not quite. (About .001" interference). It is important that the shaft have an outside diameter about 0.050" less than the outside diameter of the piston. we only want to lap the piston---not the shaft supporting it. The lathe is ran at about 60 rpm, and the cylinder is held by hand and slid back and forth over the piston. making sure that the piston extends out of the cylinder about 1/2" at both ends of the stroke. At first this requires a strong grip, but the aluminum oxide paste works very quickly and it loosens up quickly. This is where you want the cylinder to be simply round with no features, so that if it "grabs" you can quickly let it go.


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## Brian Rupnow (Apr 12, 2018)

Dug deep into the Rupnow fortune today and ordered a set of 5" cast iron flywheels from Martin Model and Pattern for this new engine. I have a ridiculous number of home built engines with every conceivable type and style of flywheels on them, all made by myself except for the ones on my Rockerblock engine, which I had water-jet cut. Figured it was time to spend a bit of money on something "store-bought".


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## Brian Rupnow (Apr 13, 2018)

This is something you may find interesting. Due to the way this engine is laid out, I can't have a normal tappet riding on the cam. Instead, the bronze shaped cam follower fits around the cam and is pinned to the 3/16" rocker shaft, as is the yoke which will operate the air valve. As the crankshaft rotates, it will move the cam follower in a rocking motion, that will in turn cause the end of the Y shaped piece to move up and down, to operate the air valve.


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## Brian Rupnow (Apr 13, 2018)

The solid model has been updated to show it with the new 5" diameter flywheels I have ordered, (I think they are much better in proportion than the previous 4" diameter ones.) In one of the models the near side flywheel is hidden so you can see the cam follower and the Y shaped lever that controls the air valve.


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## Brian Rupnow (Apr 14, 2018)

I was flying right along, beginning initial assembly. Then I opened the box with my #6-32 taps in it. The bottoming tap was broken off (I remember doing that and had meant to replace it). The blind holes for the taper tap are only 0.470" deep, and the taper tap bottoms out before it starts to cut a full size thread. (these are the bolts which hold the support feet to the cylinder.)  There is nowhere in town to buy a replacement tap.---Ahh bugger!!! Oh well, I've done enough for today anyways.


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## RonGinger (Apr 15, 2018)

Nice work Brian. Any chance you will pack up some models and come over to Detroit next week for the NAMES show. I'm sure a bunch of us would like to see them and get to meet you.


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## Brian Rupnow (Apr 15, 2018)

Thanks for the invitation, but no, I won't be coming.---Brian


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## Brian Rupnow (Apr 15, 2018)

The ball nosed endmill does add a very nice feature when it is used. What doesn't add a nice feature is when you misread your own drawing and put two counterbored holes in the wrong place. Damn, I hate it when I do that!!! Fortunately, the tops of these counterbored holes will be hidden under the air manifold. So--clean it up, set it on a piece of cardboard, and fill the two offending holes with J.B. weld. When the J.B.Weld sets up, I will rebore the holes 0.100" inboard of where they currently are.


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## Brian Rupnow (Apr 15, 2018)

Totally bummed out here. Two solid days of ice storm. I'm even tired of machining things. However, I did accomplish one thing today. The pivot bracket that fits onto the open end of the cylinder has to be silver soldered together in a jig. The bracket is brown in color, made from 3 separate parts. the jig (green) was made from two pieces of scrap out of my bin. The three shcs in the jig are an exact copy of the bolt pattern in the open end of the cylinder.


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## werowance (Apr 16, 2018)

i like the supports for the cylinder.  very nice and look good.

question on the 600 grit laping paste.  this sounds very much like valve grinding paste that you would get from the car parts store.  pretty much sand suspended in grease looking stuff.  is that what you are using?  or are you using the diamond paste that comes in the syringes?   havnt seen 600 grit in that stuff.  not to say they don't make it.  do you have a brand name or anything of what you are using?


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## Brian Rupnow (Apr 16, 2018)

The valve grinding paste for automotive use is far too coarse for working on models. I keep a stock of 300 grit,400 grit, and 600 grit in stock. I didn't have any diamond paste on hand this time or I would have used it. Do a google search for "moco lapping compound". Mine is aluminum oxide dust in a heavy wax or white grease.


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## werowance (Apr 16, 2018)

Thank you  will google it.


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## Brian Rupnow (Apr 17, 2018)

The parts to make up my pivot bracket have been machined and set up in my jig to be soldered. I don't have a real warm fuzzy feeling about this, because I just know that the solder is going to run onto my socket head capscrews and make them part of the assembly as well. Not a total loss, because if that happens I will just machine the capscrews out afterwards. Wish me luck.


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## Brian Rupnow (Apr 17, 2018)

So, there we have it. The jig worked just as intended. As I had feared, I managed to solder all three socket head capscrews  into the assembly. I have used White-out and other agents to stop the flow of silver solder in the past with so-so results, but this time I didn't have room to use it. Not a huge problem--I flipped the part over and milled the screws out from the back side of the jig with a 1/8" carbide endmill. After a period of sanding, filing, and "fettling" I have a respectable soldered assembly.


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## Brian Rupnow (Apr 18, 2018)

I was able to save the cylinder head. Moving a hole and a counterbore by about   3/4 the diameter of the original hole is always a tricky proposition. I filled the "bad" holes with J.B. Weld about two days ago. Set things up this morning in the mill vice and very cautiously put the new holes in with a 1/8" milling cutter (plunge-cut). Once the new holes were in, I used the correct drill (which was 0.130" diameter) and drilled thru the two holes. Once the correct holes were in, I used the correct counterbore. All went well, and the counterbores in question will be covered by the valve block.


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## CFLBob (Apr 18, 2018)

Would you point out the holes you moved?  Maybe draw a line on the picture in Paint or something?  By the 4/15 post, it looks like it should be those two near the bottom (left?) edge in the picture

They look far too big to be .130" diameter.  If those are .130, what are the small holes?  .025?


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## Brian Rupnow (Apr 18, 2018)

CFLBob said:


> Would you point out the holes you moved?  Maybe draw a line on the picture in Paint or something?  By the 4/15 post, it looks like it should be those two near the bottom (left?) edge in the picture
> 
> They look far too big to be .130" diameter.  If those are .130, what are the small holes?  .025?


The through holes are 0.130" diameter. The counterbore is 0.2" diameter. Sorry for the confusion. The holes are for #5 shcs. which are 0.122" diameter.--Brian


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## Brian Rupnow (Apr 18, 2018)

Today marks the first full assembly of all the parts so far (except the piston). I'm fairly pleased. Things will start to look a lot better when my flywheels arrive. I still have to make an oil cup and drill/tap the cylinder for the cylinder head. The cylinder head is finished, but I still have to make the valve body that sets on the cylinder head as well as the valve rod itself and the link that ties things together.


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## werowance (Apr 19, 2018)

looking good


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## Brian Rupnow (Apr 19, 2018)

I have to make a new angle for my dangle!! The straight pivot bar that rocks back and forth as the engine runs is just too close to the cast cylinder when the piston is at top dead center. It won't let the crankshaft make a full revolution. I have milled, filed, and sanded away the end of it until I finally decided "This ain't going to fly". I have a new one designed that still keeps all of the important pivot points in the same plane, but the bar has a curve added to the bottom so it will clear the pivot bracket and the end of the cylinder.


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## canadianhorsepower (Apr 19, 2018)

Brian Rupnow said:


> I really, really, don't want to start another build right now. . I really like the style of this engine, and may design a single acting air motor based on this.
> 
> 
> 
> ...



Hi , is it my eyes, or what you are building is a copy of the video with your name on it as a builder????


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## Brian Rupnow (Apr 20, 2018)

canadianhorsepower said:


> Hi , is it my eyes, or what you are building is a copy of the video with your name on it as a builder????



Either it was an evil clone or you read the title wrong Luc.


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## Brian Rupnow (Apr 20, 2018)

I got off early this afternoon from my "real" job, so I came right home and built a new pivot bar for the engine I am working on. Now, although everything is very "stiff" I do have it so that the crankshaft can rotate thru a full 360 degrees. There is still a fair bit to be done on this engine, but I always think it's a milestone when I get all the big pieces together and can go thru a full rotation of the crankshaft without something going "clunk".
[ame]https://www.youtube.com/watch?v=q0mZefCfBoE&feature=youtu.be[/ame]


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## Brian Rupnow (Apr 20, 2018)

These guys just showed up in the mail. They measure about 5.1" o.d. with a 0.520" wide face. I was expecting them to be a little heavier, but since I never bought flywheels before, I wasn't sure what to expect. Hopefully, they will serve the purpose. I guess I'll find out as I go along. I have paid over $100 Canadian funds for these, including the shipping by mail. I have to wait and see my bank statement before I'll know how much more than $100 they cost.


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## Brian Rupnow (Apr 21, 2018)

The cylinder head and the valve body are finished and assembled. I spent a couple of hours chasing down "tight spots" in the assembly, and now I have it so it will turn over very easily. I'm going to take the rest of today off and read a book!!


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## Brian Rupnow (Apr 22, 2018)

Who can tell me where I can get outside circlips  that fit into a groove cut into a 1/8", 3/16" or 1/4" shaft, and the tool that you use to insert them? I always have a bunch of 1/8" pivot pins on the stuff I build, and never have a good way to keep them in place. I know there is an insertion tool for metric circlips, but I have never seen one for inch size circlips. Circlips are also known as external snap rings. I have a terrible time trying to put them on with pliers. Before I can get one in place, I have lost five others zooming across my room and disappearing forever.--Whoops---I may have answered my own question.--I checked out the Spae Naur catalogue looking for alternative names for these things, and I see that they sell the tool.-Brian


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## Brian Rupnow (Apr 22, 2018)

No real work going on today. I'm just dicking around to see how I'll hold these flywheels to turn them. I think that I can assume that the spokes are all in one plane. If I cut a piece of 4.1" dia. wood x 1 1/2" thick and turn it round, with a centerhole large enough to clear the hub and hub radius, then make up five metal brackets, I can make the brackets to a thickness that when screwed down tight will firmly grip the 5 spokes. Then I can hold the round wooden part in my lathes four jaw chuck. I don't want the wood to register on the inner diameter of the outer rim, nor on the hub area. I want it to have a bit of "float" so that when the yellow screws are tightened down the wood is not being positioned by the rim nor the hub. Then I will dial in the four jaw so that the inner side of the outer rim is  concentric to the spindle. This will let me machine the outer diameter and the bore and possibly the two sides (not sure about that yet), so everything should be concentric and in plane with the spokes.


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## Ghosty (Apr 22, 2018)

Brian Rupnow said:


> Who can tell me where I can get outside circlips that fit into a groove cut into a 1/8", 3/16" or 1/4" shaft, and the tool that you use to insert them? I always have a bunch of 1/8" pivot pins on the stuff I build, and never have a good way to keep them in place. I know there is an insertion tool for metric circlips, but I have never seen one for inch size circlips. Circlips are also known as external snap rings. I have a terrible time trying to put them on with pliers. Before I can get one in place, I have lost five others zooming across my room and disappearing forever.--Whoops---I may have answered my own question.--I checked out the Spae Naur catalogue looking for alternative names for these things, and I see that they sell the tool.-Brian


 Brian,
Look at hobby shops, car parts, they use a lot of small "C" and "E" clips, you may have to look a metric sizes though. I use 2mm "E" clips on my valves as retainers.
Hope this helps.
Cheers
Andrew


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## Brian Rupnow (Apr 22, 2018)

Thanks Andrew--I knew there was another name for those things, just couldn't remember what it was.


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## Blogwitch (Apr 22, 2018)

If ever you need larger flywheels, this is the place to get them from.
They do up to 16" and are very well made with the outer rim usually ready machined.

The postage is very reasonable as well.

https://www.rc-machines.com/en/model-engineering/flying-wheels

John


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## Brian Rupnow (Apr 23, 2018)

Just finished machining flywheel #1.-A totally different experience!!! I have never machined a casting before. My lathe and I are both dirtier than a pig from iron dust. The picture I posted earlier of my proposed set-up seemed to work very well. I can't get over how far out many parts of the casting were from the finished ideal, although I understand that is typical with sand cast parts. In this one set-up I was able to machine the outer face of the flywheel, both sides of the rim, cut off and true up the outer diameter of the hub, and finish the bore. All that remains is to flip the flywheel around and hold it by the outer rim in the chuck to face the far side hub.


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## Brian Rupnow (Apr 23, 2018)

Blogwitch said:


> If ever you need larger flywheels, this is the place to get them from.
> They do up to 16" and are very well made with the outer rim usually ready machined.
> 
> The postage is very reasonable as well.
> ...


Thanks John.--Might be a bit of a stretch to ship from Luxemburg to Canada, but this is good info for the U.K. guys.---Brian


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## Foozer (Apr 23, 2018)

You're a 'Man on a Mission' - Is fun to watch and learn . . .


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## Brian Rupnow (Apr 23, 2018)

I love the proportions. I think the 5" diameter is perfect.


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## Brian Rupnow (Apr 23, 2018)

Not hard work, just a lot of work. and it's something new that I haven't done before. Both flywheels are fully machined except for the set screws. I am going to have to spend some quality time with my Dremel tool to clean up flash lines between the spokes, but overall I'm happy with my results. I also have to figure out how the guy who's flame-eater inspired this build got the machined areas of his flywheels so shiny.


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## Brian Rupnow (Apr 23, 2018)

And now---Here's the rest of the story. I machined everything with  an HSS tool, with the lathe running at 200 rpm. Most of the time my depth of cut was 0.010". The flywheels cleaned up at 4.950" outer diameter, 0.472" wide, with 0.70" diameter hubs, and of course I drilled and reamed 0.375" center-holes to match the crankshaft. The original castings were 5.1" diameter x 0.520" wide. I only machined enough away from each surface to get past the casting finish.---Brian


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## Blogwitch (Apr 23, 2018)

Machined cast iron should come out almost like chrome.
I use different grades of steel wool to obtain such finishes, and not only on flywheels, but it is a bit dicey as your fingers get very close to spinning parts.

If you can get or make yourself a small die filer, spokes on flywheels can be cleaned up in minutes. A very underated machine.

John


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## Brian Rupnow (Apr 24, 2018)

I've whittled this thing down to the point where there are only two pieces left to make before I can try to run it. I need the 1/4" diameter valve and the link that attaches to it, but I'm too tired tonight to make anything. I started the valve this morning before I had to go across town on one of my "real" design jobs, then promptly screwed it up when I returned home this evening. But--Tomorrow is either going to be really exciting or else very disappointing. I'm still not 100% certain that I have the valve designed properly, but it's basically a "cut and paste" of the valve I built a few years ago when I redone the Chuck Fellows engine. I can paint and polish things after I know the engine is going to run.


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## Johno1958 (Apr 25, 2018)

Beautiful engine Brian good luck with it.
John


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## Charles Lamont (Apr 25, 2018)

Brian Rupnow said:


> I machined everything with  an HSS tool, with the lathe running at 200 rpm.



That is 260 ft/min on the rim. The recommended speed for HSS tools on grey iron is about 60 ft/min (depending very much on who is doing the recommending).

To finish cast iron I use silicon carbide paper and kerozene, with the paper wrapped round something flat, like a file with a sound handle, so as to avoid the mortal sin of rounding the crisp geometry.

Your side of the pond people generally seem to go for a far higher degree of shine than would be considered good taste here, where going mad with a buffing wheel is reserved for bits of motorbike.


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## Brian Rupnow (Apr 25, 2018)

Well, we didn't quite get there today, but we got awfully close. I have two gaskets to make and I have to set the valve timing, but other than that I think I'm ready for a trial run.----Tomorrow
[ame]https://www.youtube.com/watch?v=58RaNBUE09I[/ame]


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## werowance (Apr 26, 2018)

so the brass arm riding on the eccentric is what is running the valve right?  held on the pivit pin via a set screw?   
its looking very nice.
looking forward to the test run.


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## Brian Rupnow (Apr 26, 2018)

Morning has come, my gaskets are made, my engine is timed, but it won't run. OH POOP!!! Howevah--if I disconnect the link which runs from the Y shaped yoke and lift/lower the actual valve "by hand" I can find one position where 
 air is being passed to the cylinder (and this thing is strong considering the 7/8" bore), and one position where no air is being passed to the cylinder. This may simply be a matter of tailoring the length of the link so the two  positions I found "by hand"correspond with the max/min positions of the yoke. Maybe an adjustable length link until I find the "sweet spot".


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## Brian Rupnow (Apr 26, 2018)

So--Here we go with the old adjustable link trick!!


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## Brian Rupnow (Apr 26, 2018)

So--all it took was a little bit of patience and a bit of luck, and Hey Presto--We have a running engine. It's beautiful!!! I have painting and polishing yet to do, but the design is proven. I will be selling the plans to this engine for $25 Canadian funds. Thank you for all sticking with me through the build.---Brian
[ame]https://www.youtube.com/watch?v=zDU2BIC701c&feature=youtu.be[/ame]


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## Ghosty (Apr 26, 2018)

Brian, Congrats on another runner.

Cheers
Andrew


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## Johno1958 (Apr 26, 2018)

Congrats Brian .Wonderful engine
John


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## werowance (Apr 27, 2018)

Very nice.  the motion is similar to your rocker block ic engine.  I like it.
congratulations


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## Brian Rupnow (Apr 27, 2018)

Now here is a very interesting shot. I gathered up all the random pieces of sandpaper I could find, and mounted the flywheel on a 3/8" arbor and put the arbor in my lathe. With the lathe rotating at 250 rpm. and working on the face only, I first wrapped #180 grit paper around a flat stick and held it against the rotating face. I kept the stick and sandpaper moving a bit, for a slow count of 50. Then I repeated with 220 grit, always keeping the stick and sandpaper moving just a bit for another count of 50. Then I repeated with 400 grit, then with 1500 grit, then with a pad of "ultra-fine" Scotchbrite held in my hand--no stick. The face had by that time taken on a mirror like finish. I was so pleased with this that I then done exactly the same thing to both sides. At this stage I have not used any buffing wheels nor compound.


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## Brian Rupnow (Apr 27, 2018)

Both flywheels were given the same sandpaper treatment, then polished with an old Eastwood polishing kit left over from my hot-rodding days. all buffs were ran at 450 rpm. First a sisal buff with emery compound, then a spiral buff with stainless compound, then a loose cotton buff with white rouge. It certainly makes a big change from the machined cast iron finish.


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## Brian Rupnow (Apr 27, 2018)

A few pages back in this thread I was asking about e-clip insertion tools. I found out that Spae-Naur in Kitchener Ontario has external retaining rings (which are less fat than an e-clip but do the same thing) and also sell the installation tools. The tools aren't cheap---about $40 each, but I figured that after 27 engines I deserved them. So--I got 100 of 1/8" shaft external retaining rings, and 100 of the 3/16" shaft external rings, and the tools to insert both sizes.


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## JC54 (Apr 27, 2018)

Another weird and wonderful engine Brian, neat, BRILLIANT. 
       As a newbie I have been looking at your earlier posts from your first engine to this one (No27?) and have had a lot of questions answered that I wanted to ask, almost like a tutorial. Keep up the good work, WHAT'S NEXT?


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## Brian Rupnow (Apr 27, 2018)

JC54--Nothing for a few months I hope. I've went crazy building engines this past winter, building about 5 I think. I hope to document more of my "finishing strokes" on this most recent engine such as paint and polishing, but I need a break from building.


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## Brian Rupnow (Apr 27, 2018)

A question now, related to the finishing/painting of the flywheels. The flywheels are made from a split pattern, and the split is exactly on the center of the spokes. There isn't a lot of flash, but there is a definite ridge on each side of the spokes and the inside center of the outer rim. Now, I have the option of sanding that ridge away with my Dremel tool, but in so doing it will leave a smooth surface which does not match the general "as cast" surface of the rest of the flywheel where I haven't polished it. I definitely don't want to sand away the "as cast" surface on all the flywheel. Maybe I should just leave the ridge alone and paint everything that I didn't polish today. Opinions please, and pointers from those who have painted flywheels themselves.---Brian


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## mayhugh1 (Apr 27, 2018)

Take a look at Rustoleum's textured paints.


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## TonyM (Apr 28, 2018)

I want my flywheels it to look scale and the base casting finish is too coarse for that. I was able to remove the cast lines with the dremel as well as buff the other surfaces a bit to match without giving too fine a finish.


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## Charles Lamont (Apr 28, 2018)

In the best full size work the flash and rough bumps on the casting would be removed and then then a filler used to to produce a smooth surface. This applies to model work too. Polyester car body filler does the job.

But before you do that you should put a chamfer or shallow recess on the inner edges of the rims so that the bright part of the rim has a true running inner edge. You would then paint right up to the flat face. This diguises the run-out of the as-cast inside of the rim.


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## Brian Rupnow (Apr 28, 2018)

I can't even begin to tell you how well these retaining ring inserters work. After years and years of having small retaining rings fly across the room and disappear forever into swarf and cobwebs, this is just like magic. It still takes a certain finesse to load them into the spring loaded jaw of the insertion tool but nothing compared to the old needle nosed pliers trick.


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## Brian Rupnow (Apr 28, 2018)

It's time to start blowing this thing apart for painting and polishing. Fortunately this is an extremely easy engine to dismantle. I have to buy a new 8" spiral buffing wheel, as my old one is clogged up and difficult to use. I will polish all the brass bits and paint the cast iron cylinder and cylinder head and the aluminum feet. I like the colour of the original flame-eater that inspired this build, so will probably go for the same blue. I'm not going to spend a lot of time prepping for paint. Probably just wipe everything down with laquer thinners to get rid of any grease or oil, then buy a can of Tremclad rattle-can paint to paint it with.


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## johnmcc69 (Apr 28, 2018)

Another fantastic engine design & build Brian. It's going to look good with those colors & polished pieces. I also really like the clip installation tools, gotta add those to my "wish list".

 John


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## Brian Rupnow (Apr 29, 2018)

A note to those who are building this engine from my plans--


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## Brian Rupnow (Apr 30, 2018)

I got notification by email that my 8" spiral buff and buff rake were shipped out today from Pennsylvania. I'm so sick of making little engines that I could run in circles and bite myself. Our snow is finally gone here, and I took the day to drive up to Bancroft and visit my ancient mother who will be 98 years old in August. Nice day, good visit, nice trip. Once I get this engine painted and polished, I sincerely hope that nothing else catches my fancy until next fall.---Brian


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## Brian Rupnow (May 1, 2018)

Temperature went nuts today, up to almost 80F. (Wonderful) I hustled my butt down to Canadian Tire and bought a rattle-can of dark blue Tremclad paint, masked off the shiny parts on my flywheels, then set everything up in my main garage and painted it. All of the cast iron is painted now (except the piston which won't see any paint). I've never been a fan of rattle can paintjobs, but for something this size it isn't worth buying separate paint and reducer. I'm quite happy with the colour.---Brian


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## Brian Rupnow (May 1, 2018)

I just spent 20 minutes in the garage, untaping the flywheels and washing any blue paint off the sides of the flywheels. The paint always "migrates" under the tape edges when you are masking off steel, and if you don't catch it just at the right time it is very difficult to clean off-----leaves a ragged looking edge. You want the parts dry enough that the paint won't stick to your fingers, but still not absolutely dry. A rag wrapped over the end of your finger and wetted with paint thinners works excellent for this, but it's a rather delicate process. Someone asked if I was going to clearcoat the polished face and edges of the flywheels, and I said no, because all of the polishing compounds you use are wax based and will protect it from rusting.--That is still correct---But--if you are going to paint the flywheels you have to be sure and remove all of the wax first with strong laquer thinners. So--consequently, when my paint is fully cured I will apply a bit more "final polish" compound to the unpainted surfaces.


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## Brian Rupnow (May 2, 2018)

I'm down to the point where everything is painted and polished. I had hoped to capture some of the brilliant shine on the brass, but it doesn't show up very well in this picture.---And---when I went to take another shot I got the "Charge Battery" message on my digital camera. Reassembly should be a fairly simple exercise, but I just got a call from one of my customers and that will eat up my afternoon. Tomorrow I will put it all back together. When it's all blown apart like this, there aren't very many pieces, are there.


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## CFLBob (May 3, 2018)

Brian Rupnow said:


> ... I'm so sick of making little engines that I could run in circles and bite myself. ... Once I get this engine painted and polished, I sincerely hope that nothing else catches my fancy until next fall.---Brian



Brian, I've got to tell you how much I admire your work - and the speed you get it done.  I started on my Duclos flame eater weeks ago and just got the first piece more or less done.  It still needs more finish work.  

Yeah, there were a lot of interruptions like spring planting and stuff around the house that needed to be fixed, but the real reason is that I'm a newbie at this stuff and most of the time I don't know what I'm doing.


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## Brian Rupnow (May 3, 2018)

The painting and polishing is finished, and the engine is reassembled. I'm very happy with the way this engine turned out. I've built so many engines over this past winter that I hope not to start anything else between now and fall. Thank you to the people who have followed this build on the forum.---Brian
[ame]https://www.youtube.com/watch?v=8Mjw4YLCt9E&feature=youtu.be[/ame]


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## ShopShoe (May 4, 2018)

Gotta say it again, Brian.

Nice build. Just the right amoung of Bling. Good paint. Smooth Running and very interesting to watch.

I do have to admire the speed at which you did this one. Enjoy your time off this summer, but I hope you come back inspired again. I look forward to your posts.

Regards,

--ShopShoe


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## Johno1958 (May 4, 2018)

Such a nice  engine to watch Brian .Have a good break but I bet there will be some plotting and scheming before long , then an itch ........
Cheers
John


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## Brian Rupnow (May 7, 2018)

About a week ago I ordered an 8" buffing wheel and a buff rake from Eastwood. Of course I was too impatient to wait another week to finish polishing the engine parts, so I bought a 6" buffing wheel locally to get the job done. Today, my order showed up. My God--What a ferocious looking beast that buff rake is!! I've never had one before now, so wasn't sure exactly what to expect. This thing looks like it would scrape the barnacles off the Titanic.


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