# Elmer's #33 - a novice makes chips



## thayer (Dec 4, 2012)

As a bit of reintroduction, I've had a manual Sherline 4400 lathe for a while and a couple years ago complimented it with the A2Z CNC Monster Mill to maintain Sherline compatibility. Knowing little of operating a mill or CNC at the time, after a few basic bits and pieces I christened it with a couple of Elmer's simple engines, a #25 wobbler followed by the #2 twin vertical wobbler, seen here.
http://www.homemodelenginemachinist.com/f14/elmers-2-25-a-8201/

While the main use of the tools has been making bits and pieces for my radio control airplanes, I have long meant to revisit Elmer's catalog and tackle something a bit more complex. A few days ago I did just that. I've now begun his #33 horizontal mill engine and began with the cylinder block to see right away if I was up to the challenge. I'm not fast with my projects, but try to build cleanly and accurately. I will update this thread as I go but am rather sure that life will keep it from running this year.

My main goal, beyond finishing the mill engine of course, will be to pass along a bit of inspiration to others like me who are new to machining. This forum can be at once both inspiring and rather intimidating. I've found twice in the past, and expect to again, that you don't need to be a master machinist to enjoy turning out a working steam engine.







This first photo shows the basic start. My scrap stock was a little oversize, so I made a several passes with the Sherline flycutter to bring it down to its nominal cross section of 1x1 inches. Note the slight relief in the top of my vise jaws. Inspired by Tryally's slim vise, I inverted the stock jaws and milled the relief as a "permanent" set of parallels. I will occasionally skim them when I can't indicate them accurately. Note the layout ink and scribing. I decided to lay out this project as accurately as possible, despite the availability to just use the DROs and run some G-code.

Of note to those still sitting on the fence is the piece of wood used to contain some of the fly cutting swarf. I have a stash of used breaking boards from our local karate studio, gathered after one of their semi-annual black belt testing sessions. If an 8 or 9 year old kid can earn an internationally recognized black belt after 4 years of training, surely we can muster enough confidence to carve a little aluminum and brass.


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## thayer (Dec 4, 2012)

The trued-up 1x1x1.375 cylinder block back in my lathe and ready for boring. I am using a cheap import drop indicator to set the 4-jaw for the appropriate 1/32 offset for the cylinder. I did an initial center by eye using the concentric rings, then indicated opposite faces to bring it in tight before offsetting for the bore.






I used this same setup to clean up the ends of the rough sawn blocks and face them to length. Careful adjustment of the rough block in the chuck allowed me to maintain it parallel to the bed within half a thou along its length when I originally faced it, and again now. Surely that will be good enough for this project.

FWIW, the shop-made indicator holder is that shape because I had an offcut about the right size.


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## thayer (Dec 4, 2012)

Step three was opening up the bore. I started with a center drill in the tail stock, then stepped up .040 - .050 at a time until just shy of .400. I then used the largest Sherline boring bar to bring it out to .500. 






I actually left it a bit shy to give me some room for honing the cylinder after finishing the rest of the operations on the block.


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## thayer (Dec 4, 2012)

The outside of the cylinder gets turned round for .25 on each end and I didn't think I could safely hold it to turn the second end without ripping it out of the jaws or mucking up the first. 

I ended up making a slip-fit mandrel from 12L14 steel, first using a steady rest to center drill the ends. I then turned it between centers to size.
















To hold the cylinders, I left the center in the headstock and replaced the lathe dog and faceplate with the 4-jaw. With the mandrel back on centers, I lightly griped the block to hold it while I turned the second end. 






I know better and should have padded the jaws before turning the second side. I didn't tighten them much, but the hammering from the interrupted cut was enough to give me something to polish out later.


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## thayer (Dec 4, 2012)

Here are two cylinder blanks bored and ready for the valve porting.






I did a pretty careful job of laying out the ports and it was a good thing too. Somehow I missed on my edgefinding operation by a bit. Before spot drilling the 13 holes for the porting and steam chest mounting, I dimpled the face about .005 to make sure I was good to go with the drilling sequence. My first pass showed the error so I rechecked the edge and got within a couple for the next round. You can see the second round of smaller dimples are a lot closer in Y and nearly dead nuts on for X. They are intentionally smaller so I would know which was second set.






I figured that was close enough and pressed the go button. Spot drilling with a #1 center drill, followed by peck drilling sequences for the intake and exhaust ports, and steam chest.






The holes all fit within my layout lines so I think it is pretty close. The step in the exhaust port bores comes from the center drill being slightly larger than the final bit and going deeper than I needed to. The intakes have an .005 skim as well to check the G-code.


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## thayer (Dec 4, 2012)

I've been admiring everyone's dedicated taping stands on HMEM and can certainly see the appeal of such a project. I haven't gotten to it yet, but did upgrade my tapping capabilities on this project.

Previously I had placed my lathe center in the mill headstock then jogged it down onto the top of my tap handle. Tapping meant one hand turning the handles with the other on the keyboard chasing with the center.  As you can imagine, that was pretty slow and didn't do a great job holding the handle steady.

To improve my tapping going forward, I took an 18x.312 stainless shaft I salvaged from an old printer, turned a 60-degree center on the end and bored out an unused tool holder to just clear the shaft.






Now I set up much the same way as before, but thread the 5+-ounce stainless shaft through the spindle and let gravity feed it as I advance the tapping handle. This works beautifully well and is a lot faster than the old method. In essence it is poor-man's version of the spring-loaded center often used. 






If you get the bore in the holder a little looser than you wanted, you can turn a drop-in collar for the upper end of your Z-axis spindle as well. I haven't done that yet and am taking solace in that this new setup has a lot less slop than I had with the previous method.


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## thayer (Dec 4, 2012)

Next up is drilling the long diagonal ports. I used a digital TiltBox to set the cylinder at the proper angle. I doubt it is all that accurate, but I don't have a sine bar yet and the tolerance for this op was pretty loose.






I then used my height gauge to determine how deep I wanted to drill. I measured off the notch in the inclined lip of the cylinder bore and the target port.


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## thayer (Dec 4, 2012)

Last but not least, the current status of the cylinder. Yes, I have a second block but that one has a way to go to catch up. Hopefully I won't need it for this project.






For anyone working on one of Elmer's designs, carefully check the geometry of the notch in the end of the cylinder. He calls for a 1/32 offset* but I could not get the drill to catch in the bottom with that dimension. At 1/16 I had no trouble. The image shown is the end with the larger offset.






That's all for now. I am quite pleased with my work so far and think it looks pretty good, despite the harsh lighting.

*I have now realized that I had read the print wrong. The indicated 1/32 dimension is for the centerline of the port, not how far into the cylinder wall it is offset. That all makes a lot more sense to me now and I now believe the photo below shows the porting as Elmer intended.


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## thayer (Dec 6, 2012)

I got into the shop briefly this evening and have some stuff I will post later since it is late now. In the meantime though, I have a little quiz. Can anyone guess what this little piece of aluminum is all about? 






Its outside measurements are roughly 1.6x1.9x.375 inches with the hole at 10-32. And yes, it is related to this project.


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## johnmcc69 (Dec 6, 2012)

I created CAD models of this engine but I don't
Recall that as one of the parts. I went off the plans
from the Jon-Tom site. Where did you see this
on the drawings?

John


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## thayer (Dec 6, 2012)

It is not on the drawings. Just something I whipped up last night.


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## robcas631 (Dec 6, 2012)

An arm mounted horizontally that transfers motion from the crankshaft  that controls the intake and exhaust


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## thayer (Dec 6, 2012)

Partly close Rob. It does control the intake and exhaust, at some level, but not like you describe.

Before the reveal though, here are two little layout / test tips I find useful as a timid beginner. My mill is CNC and I will usually "cut" some air before committing tool edge to metal.  If you have a piece of stock that is a little marginal in size, or just want to see your robot run a bit to give you confidence, you might appreciate that a standard Fine Point Sharpie can be securely seated in the #1 MT of a Sherline spindle. This gives you a pen plotter of sorts. Seeing ink along the toolpath on your actual stock, secured to your table, buys a lot of confidence. At least it did for me.

Step one is to manually edit your g-code to make one lap around the path at Z0 minus a few thou. I will usually bump the speed up a bit as well. Jam the Sharpie into place, then start the spindle at a slow speed and apply light pressure with your fingernail or some sort of stick to true up the wobble.  You don't have to get it perfect, just slow down the big swirls. Set your Z0 with the tip just touching down and then press the go button.






The path you see above was with a bit of wobble going on, but it left a path about an eighth wide which happened to correspond to the end mill I was using. This made it an easy task to confirm that the mill would not crash into the vise before I started cutting. Yes, this is thinner stock than the part you saw previously. I made two, the first  from .125 stock which I decided was not thick enough. It worked, but I knew it could be better.

If you really want to get fancy, you can draw the part in one color and the tool offset in another. Don't forget to reset your g-code, Z0 and feed rate before you start cutting.


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## thayer (Dec 6, 2012)

When it comes time to set your cutting tool to Z0, getting it to "just" touch down on your stock can be a little intimidating for a beginner. You read about auto probes, cigarette paper feeler gauges, 1-2-3 blocks and even candy wrappers being used. (http://www.homemodelenginemachinist.com/f13/beginners-tool-box-19342/index3.html#post201449)

Truth be told, when you are going to cut through a piece of stock the Z isn't really all that critical.  I will usually bring it down close, then jog down .001 at a time using my keyboard. While bringing it down I rock the spindle back and forth using the Sherline #2049 handwheel and just watching for the first light mark or curl at the cutting edge. I'll call that first touch Z0 and proceed.

Jogging at .001 as you feel for the surface can be slow going though, so I usually make a slow Z move to get the tool as close as I dare, hopefully just above the surface. A strong backlight provides a nice visual aid letting you easily see the gap between the tool and the stock. If the surface is reflective, don't forget that the tool and its reflection are 2x the actual height apart.  Here is a photo showing the tool hovering just a few thou before touchdown.


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## thayer (Dec 6, 2012)

Does this help?


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## thayer (Dec 6, 2012)

How about this?


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## thayer (Dec 6, 2012)

As you've no doubt sorted out by now, it's just a simple little cradle that lets me set the cylinder block at the proper angle for drilling the steam passages between the cylinder and porting. Just press the cylinder into the seat against the base of the vise and carefully it snug up.

Elmer used that cylinder design for several of his engines so the odds are pretty high that I will be drilling these passages again in the future. I wasn't completely happy with the first one and I've already got a second cylinder blank that may go on his #29 Vertical Mine engine next. This seems like a better way to go and likely more accurate than the TiltBox which calls out a +- 0.2-degree tolerance. Even if the angle isn't perfect, it will be more consistent.

Finding Y0 comes from indicating the edge of the block, making a few measurements of the actual part and doing a little math. Centering this passage is not critical so if I miss center by a little it really doesn't hurt anything beyond my pride.






The part I thought was brilliant for a beginner, if I do humbly say so myself, was coming up with the little nub above the cylinder to set my X0. 






Touching off that with my edge finder puts my spindle directly above where I want to come in with the 1/16 end mill to start the passage. 






Actually cutting this part took 8-10 minutes after I had it designed (Ashlar-Vellum Graphite) and generated g-code (d2nc in Mach3). I was feeding at 16 ipm with a .020 doc. The stock was a scrap of 3/16 aluminum tooling plate. The finish of the cut could be better, obviously from letting the chips sit in the slot while I chased around it. I used TapMagic applied with a small plastic pipette and tried to clear the chips as best I could with an acid brush. I could clean it up with a finishing pass but doubt I will.

The cylinder with the dychem on it is the undrilled blank, the one posing under the mill in the A2Z holder is the first one I drilled. I indicated that one just to see how close I could get the mill and it looks near enough with my Optivisor.

Oh, and the tapped hole? Sorry for the misdirection. I have no idea why it is there. It was in the stock when I got it.


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## ChooChooMike (Dec 7, 2012)

I'm a Sherline user and love all the pictures !! I've still not machined anything serious on my Sherlines and I've had the lathe and mill for 5+ years now. Gives me hope that I can really start using them 

Mike


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## thayer (Dec 7, 2012)

Mike,

I find the Sherline gear very capable, you just have to be less ambitious than you might with speeds and feeds on a larger machine. And of course, be working on smaller parts.  Elmer's series of engines are very manageable on Sherlines and you can make some very nice pieces with them. Start with something simple like his #25 Wobbler. It is a popular first engine and while maybe not as appealing as other options, it does boost the confidence significantly as it comes together and finally runs. When I did mine it was the first complex, multi-part project I had done in metal as well.

Thayer


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## Propforward (Dec 7, 2012)

That's some fine work you are doing Thayer. Not sure I buy that you're a novice......you seem to be doing some pretty excellent work!


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## thayer (Dec 7, 2012)

Propforward,

Thank you very much.  My wife and close friends accuse me of being a perfectionist and I certainly trend that way. While I haven't done a lot of machining, I have seen quite a bit of nice work and am in no hurry to get done as the process is every bit as important as the result.

Take for instance that little alignment tool for drilling the steam passages. The first cylinder is perfectly usable and I have no immediate plans for starting the #29 mine engine. Once I came up with the idea for the tool though, I figured I would explore that path a bit instead of blindly pushing fwd on the #33.


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## wongster (Dec 7, 2012)

Amazing work, Thayer!  I'll be following this thread since I've almost the same equipments has you.

Regards,
Wong


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## thayer (Dec 7, 2012)

Hi Wong, nice to see you here. It is almost time to put the boy to bed, then off to the workshop. Hmmm, what will I work on tonight...?

Thayer


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## RCGUY (Dec 7, 2012)

Thayer,

I have been watching your build and I must say I am impressed with your work. Like you I am a novice and am in the middle of building Elmer's #29 for my first engine. I have been able to continue with my build due to all the great information and build logs on HMEM.

Ed


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## thayer (Dec 8, 2012)

Working slowly and methodically seems to have its benefits. Here is the last page of tonight's chapter. I will fill in the details after I get some sleep.


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## Propforward (Dec 8, 2012)

Very nice. I agree with the slow and methodical approach. Take nothing for granted. All my screw ups have come from charging ahead.


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## gus (Dec 8, 2012)

Hi Thayer,

No worries.Practice makes Perfection.Many skills are required and picked on the way. Every goof points to a new direction to perfection. My first few Oscillating Engines were disasters too. So were the Slide Valve Double Acting Steam Engines. My two latest engines runs well.


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## gus (Dec 9, 2012)

Welcome to the "Cheese Head Socket Screw" Club. As of day one I standardised on using solely same screws but went metric to cut hassle of spanners.Easier to use Allen Keys.
Metric fasteners are easily available from Fastener Stockists.
Attached foto shows M-6 screw and Allen key. Cross-Bar Allen Keys are user-friendly.Cost a bit more over std allen keys.


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## thayer (Dec 10, 2012)

FWIW, as seen so many times before here, the SHCS are merely place-holders to confirm the fit. Eventually the cylinder will have studs and hex nuts.

Anyway, time to catch up a little.  Here's a quick sequence of spot 'em, drill 'em and mill 'em.











I'm using a #1 center drill above, followed below by the appropriately sized carbide drill and end mill from one of those assortments of 1/8-inch shank resharpened pieces you find in a plastic box for $20 or so at the local tool sale.











I am not locating a hole and going through all operations before moving on to the next. Instead I programmed my g-code to return to X0 Y0 before starting each new line of holes to compensate for the backlash. The spotting sequence then goes like this.

start at X0 Y0
spot NW then NE mounting holes
return to X0 Y0
spot left, center, right holes for upper row of valve ports
return to X0 Y0
spot left, center, right holes for middle row of valve ports
return to X0 Y0
spot left, center, right holes for lower row of valve ports
return to X0 Y0
spot SW then SE mounting holes
finish at X0 Y0

Because of the different sizes, opening up the mounting holes and valve ports was then split into two ops before I finished with milling the valve slots. This shot also shows the exhaust porting out the side.






Does that make sense? 

Let me know if you have any questions.


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## thayer (Dec 10, 2012)

Here is my steam passage alignment widget, not just posing as before, but actually being used for the first time.






In the second image below I am applying cutting fluid using one of those cheap plastic syringes you usually see in the hobby shop near the CA glue. I can get the fluid right where I want without getting nervous about them getting chewed up.


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## thayer (Dec 10, 2012)

Now on to the cylinder heads. I started with the outer one for practice as concentricity here is not critical. At least not until you get to the bolt circle.

First I chucked up a piece of 1-inch stock a few inches long. I used the 4-jaw not only to center it reasonably accurately but also to get a good grip on it due to the overhang.











After facing and a cleanup pass, I brought it down to a few thou over the cylinder OD and then turned a registration spigot that is just over the cylinder bore. This gives me a way to hold the part to clean the outer face.






I then parted it off using the parting tool for most of the cut, followed by a hacksaw to finish.  The diameter reduction at the tip is a slip fit in the cylinder.


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## thayer (Dec 10, 2012)

Reversing the head, I gripped the spigot with the 4 jaw and swept it with my test indicator to ensure it was directly under the spindle.  To get this done accurately you actually have to sweep it twice. First you hold the spindle stationary and center the part in chuck while spinning the RT for reference. Once you have that dialed in you then rotate the spindle to sweep the part with the indicator. This time you are ensuring alignment with the spindle.






But you say you already had the part true on the lathe before you moved the chuck? Yeah, it may have been, but nothing ensures that screwing the chuck onto the chuck adapter in the RT will keep it true. I find my combination of tooling results in a "lathe-centered" part being about .0015 TIR off when I move the chuck to my rotary table. It doesn't take long to bring it true, so I pretend .0015 is a big miss. In actuality, a total indicated runout is pretty good for that combo, with a +- deviation of only .0007-8. This would be fine for most things, especially if I drilled generous clearance holes in the head. On the other hand, if you can get it better reasonably easily, why not do so?






Notice the use of a calibrated Blue Raspberry wrapper for locating Z0. 






Once I had that, I lightly spotted the holes to visually confirm alignment.






Finally I spotted them deeper, then drilled through.


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## thayer (Dec 10, 2012)

Here's an abomination. Truly, a wrecked part waiting to happen.






Even though the head OD was a little oversize I tried to protect it with pads while mounting it. I had already trued up the hidden outer face at this point, so it was just a matter of turning that .300+ spigot down to .030 high and a little smaller in diameter. The lathe tools were supposed to hold everything in alignment while I snugged it up.






When I mounted the chuck and tried to indicate it I was able to get the tip or the base true, but not both at the same time. I don't know what I was thinking with this lash-up, but at least I gave up on it before I ruined the part.






A few minutes later I had a nice split bushing turned from a piece of thick-wall 6061 T-6 tubing. 






As you can see, this worked a treat after I slotted it with a hacksaw and cleaned it up.


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## thayer (Dec 10, 2012)

Repeating the operation with the cylinder and a little hand tapping gave me the results you see here.






It was late at night at this point, and I almost neglected to index the cylinder for proper orientation. I ended up hand cranking my RT until the test indicator showed zero deflection when tracing the valve port face of the cylinder block. A few minutes after taking these I snapped the photo with the SHCS in post #25 with my phone, posted it and went to bed.


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## thayer (Dec 10, 2012)

Moving to the other head, the process is much the same.






The obvious difference this time around is that you are also creating the home for the connecting rod seal and packing nut. Concentricity is key here and I was careful to ensure minimum TIR whenever I remounted the head. I know it is hard to tell, but in the image above I am recentering the 4-jaw/RT combo under the spindle before drilling and tapping the mounting holes.






Here I am obviously back on the lathe and getting ready to part it off. Leave it a bit long here for cleanup. 






And again using the parting tool followed by the hacksaw.











Yes, the lathe was turned off for the last photo as I didn't want to pinch the blade while taking the picture. I do run the lathe while sawing though, for a higher cutting rate and less need to lean on the bearings.


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## thayer (Dec 10, 2012)

Before mounting the head I measured the step in the split bushing and determined it was 0.021 shallower than the desired 3/32 final thickness of the inner head. After cleaning up the parted/sawn face of the head I set the pointer to 0.079 (-0.021) when on the bushing face.






Below I faced the head until the indicator said it was 0.032 over. This gave the desired height of the registration spigot and I then turned the rest of the head down to the final thickness, determined with the indicator reading 0.079 on the bushing and zero on the head.


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## thayer (Dec 10, 2012)

That's it for detailing the cylinder block, so this afternoon I reduced the two sides that are not mounting surfaces, leaving a few thou inside each end to clean up later. This was a roughing operation before I radius the corner between them. My plan is to tip up the RT 90 degrees and then clock it a little bit at a time while I mill away the excess to create the radius.






This image shows a small chip shield I made up from a piece of bent acrylic and chunk of aluminum slotted to accept it as a press fit. This does a reasonable job of containing the mess, or at least keeping off the left side of the bench, and still allows me to reach around and apply cutting fluid if I desire.

Here is the first side with the block held in the vise, about to go.





And the second milled down.





That gets us up to date. Hopefully I will see a little more progress tomorrow.


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## gus (Dec 10, 2012)

Thanks for the tips.The next outer head and cylinder will be drilled using the my DIY RT.


Gus


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## thayer (Dec 10, 2012)

Sure thing Gus. The one issue is that you want to really dial in the part on the RT. Once you do that you can set your offset to the bolt circle however you want. Since I wanted repeatability I carefully dialed in the RT under the spindle for each part. It really doesn't take that long.


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## thayer (Dec 15, 2012)

A little more progress over the last couple of days. First though, a question. I have been posting text and then the images that relate to that text as that is the only way I can see to do it. Yet in other posts I see text and images intermingled. I would much prefer to embed my images but don't know how. Can anyone offer up a few tips? Thanks.

So, I went to a local machinists group meeting last weekend and took along a few of my bits and pieces. They were all very polite and seemed to be interested in what I was doing, without even scorning my table top machines. Anyway, at that meeting I realized that despite the near perfect fit between the cylinder heads and my bore, I would have to set them aside and make new ones. Why?, well I made them to fit a cylinder that was a few thou under target and wasn't finished. Yes, I know I could have used them and just let the engine settle in on its own, but the bore was tapered very slightly and I wanted a better finish before I ran it. Not enough spring cuts, I guess. 

Cover your eyes now if you are squeemish. Not having any laps available, I decided a reamed bore would have to do. I loaded up the cylinder and .500 reamer with cutting oil and ran it through. That all worked out reasonably well but I now had two heads that no longer fit like I wanted. The outer end was no issue, but the inner end with the packing for the piston rod could be tough to locate accurately. Besides, I plan on painting this engine, and thought brass heads might look nice against the paint. The aluminum heads will get saved for something else I can finish out nicely slightly undersize.

And now, back to the lathe. I didn't have any 1-inch brass stock so had to throw away a lot of some 1-1/4 that I have. It pained the cheap Scot in me - I was throwing away 58% of the material before I even got started after all. Working through my steps before cutting the blank I realized that the split bush meant I no longer needed a spigot for holding and I could use less than 3/4 of an inch of stock if I was careful, including the initial saw kerf.






I didn't really take any photos since the process was essentially the same as before. First here is the outer blank turned to size with the small spigot to reference the bore. This fit is actually better than the original.  From here I parted it off and mounted it up in the 4-jaw/split bushing combo, indicated it true and cleaned the outer face with a light skim cut. Notice in the second photo that I also created a slight recess. Why? I simply thought it looked better.

The inner head is the one that is critical. I did this by turning the spigot to receive the packnut, then drilled it for the piston rod, opened it up with the #21 tap drill and then tapped it 10-32 as indicated on the plans.

I then turned the rest of the OD before the chuck jaws down to match the cylinder head so I could reverse it and put it in the split bushing. After indicating it true I then milled the final thickness and bore spigot.






So now I have a little brass to polish on this and keep bright when I am done.


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## thayer (Dec 15, 2012)

Sharp eyes above will also notice that I rounded the cylinder. 

The way to do this was with my rotary table, so I first indicated both Y & Z along the phantom lines with my Interapid. I had about a 2-inch run without hitting the outer chamfer or the centering ring so I was able to get it pretty close. 







Next I gripped one end of the cylinder in my split bushing and used the lathe to get the 4-jaw close. I later fine tuned it on the RT because I know the threaded chuck mount misses center by a thou or two. Some beginners can be intimidated by a 4-jaw independent chuck but I find it is actually pretty easy to use. eyeballing the alignment within .010 with a bit of practice is quite doable and truing it up from there is pretty quick.

In the left image below I am zeroing the indicator with one pair of jaws horizontal. Once I do that I use the hex key to rotate it 180 and note the runout, shown on the right side at about .008. I now insert a ball driver into the far chuck and tweek the two jaws at the same time to split the difference. With that done I rotate the chuck 90 and repeat with the second jaw pair. A final check on the first pair will usually show it well within what I need before moving it to the rotary table for final truing. I've done it a few times now and can get to within .001 TIR within a minute or so. Not as fast as a centering 3-jaw, but a lot more accurate.






With the chuck moved I have to spin the RT to fine tune the centering and this is a great excuse for a CNC RT. I wouldn't want to hand crank it around too many times centering the chuck.

You can see below that I used one of the aluminum heads and Sherline's adjustable tail stock to support the outer end of the cylinder. I don't know if it was necessary with my light cuts, but it did make me feel better. No point risking that many hours to find out I should have...






I hand-wrote a little G-code file to clean off the corner of the cylinder first at 45 degrees to the original reductions and ultimately stepping around to 16 facets through the 90 degrees. From here a little quick file work got it ready for primer.

As always, let me know if you have any questions or if I am doing anything wrong.


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## Propforward (Dec 15, 2012)

thayer said:


> A little more progress over the last couple of days. First though, a question. I have been posting text and then the images that relate to that text as that is the only way I can see to do it. Yet in other posts I see text and images intermingled. I would much prefer to embed my images but don't know how. Can anyone offer up a few tips? Thanks.


 
Hi Thayer! Your engine is really excellent. I cannot offer any advice on the machining aspects, but I can maybe help a little with the pictures.

I think you are "attaching" the images, right?

In order to embed the pictures into your text, so that you can write text before and after the images, you will need to use a photo hosting service - an intermediate site.

At first, this can appear a bit intimidating and overcomplicated, but once you've done it there are some significant benefits to posting pictures this way.

There are several free photo hosting sites, and some that offer extra features if you want to pay a yearly membership. To start with, it's worth signing up with a free one to see what it's about. Photobucket is a good way to start. www.photobucket.com

Basically how it works is that you store images on the photo site, and then post a link to the picture in your post.

You can see an overview of how it's done in a little thread I wrote here:

http://www.homemodelenginemachinist.com/f27/how-post-pictures-hosting-site-such-photobucket-19453/

I hope this helps - let me know if you have questions. One advantage of doing pictures this way is that you link to the same pictures from multiple forums and threads, so you only have to upload the picture once.


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## thayer (Dec 15, 2012)

Thanks, that makes a lot of sense now that I think about it.  I've now got it sorted out and will go back and embed the images as I can to help keep my logic obvious.

Thayer


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## Apprentice (Dec 15, 2012)

Thayer, I have had a quick browse through this thread, and am impressed yet confuse; due to the high calibre of this project. 

Of course I cannot offer any advice, as I am yet a '_blank canvass_' in relation to maching.  
Hopefully by following HMEM - I'll be able to learn and indulge on a craft I most certainly would like to grow as a hobby. 

I look forward to seeing how this project comes along!


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## thayer (Dec 17, 2012)

I'm not sure why, but for some reason I have been intimidated by the idea of making the valve. The only reason I can think of is because I don't have slitting saws. Well, I gathered up my courage and got into it tonight, starting with a piece of .375 sq stock about .75 long that I milled down to .250 x .220 with a 3/8 end mill.






I left it a little tall just to give me more working room in the vise. Figured I could knock down the fingers once I was done. 






That went well enough that I decided to push on. I used one of the wizards in d2nc (a fantastic addition to Mach3 by Graham Hollis) to generate the code for the pocketing, referenced off the near corner of the stock, jogged in 3/64 and pressed the go button. Sure enough, just like the scrap of wood I ran it on first to settle my nerves, the brass soon had a pretty little pocket in it that measured to the dims on the plans.






The bar coming in from the left gave me a position reference so I could end-for-end the block and cut a second one in case I needed it later.






30 seconds or so later, the second pocket was done and it was time to face the fingers.






Again I set up the stock using the stop so I could swap ends for the second. I had to hang it out the end of the vise so I could mill the slot for the rod. Since I do know enough to know that you don't want an asymmetric clamping load on your vise, I used a .25 sq. tool blank as packing for the other side of the jaws.






Did I mention yet that I can be a bit of a chicken some times? I was confident I had done all the math right, but given the hour, I decided the extra stock thickness could serve a purpose. I modified my g-code to take a .005 cut to show where the nut and rod slots would end up. With great relief I didn't see any gross errors and proceeded to cut the full depth.






Here is the first one all slotted to spec.






Cutting the second end, photographed in action through my acrylic shield. The transverse slot is for the valve rod which measures .086, hence the step you can see. For what it is worth, I stepped down .010 on each pass and the 1/16 carbide mill didn't seem to complain.






Since I had enough stock between the two parts and don't have a slitting saw, I used the 1/16 end mill to cut off the valve to length. Again, photographed through my chip guard.  I don't have a photo of the last step, trimming the fingers to length. I just put them side by side in the middle of the vise and passed back and forth with a 3/8 end mill until they were the right height.






And the fruits of my labor, ready for some final cleanup and smoothing of the face. I love how the light plays between the fingers. Almost makes the one look precious. As I always knew, they weren't hard to make at all and I now have g-code that will let me knock them out pretty quickly next time I need a few.


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## gus (Dec 17, 2012)

Hi Thayer,

The slide valves were very well done. You have just raised the bar(Standard) for me to catch up.
Gus is no good for fine details as I get impatient and work too fast.However my current QCTP which my second is doing OK with no rush and every step preplanned with Work Instructions on paper.


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## thayer (Dec 17, 2012)

Thanks Gus,

One thing I know about myself is that if the main goal is the completed project it better be simple enough for me to sprint through it pretty quickly. On the other hand, if I get to the workshop only planning to make one thing, like say some nice slide valves last night, and do that reasonably often, it won't too long before it is time to assemble my new engine kit.

Thayer


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## thayer (Dec 27, 2012)

Well, now that Santa has come and gone I can get back to the shop.

Next up is the packing nuts for the steam chest and cylinder. I figured it only made sense to make them both at the same time since they are identical, save the bore size. The final size is 1/4 inch across the flats, so I started with some 3/8 brass and threw it in the 3-jaw chuck since I had plenty of room to true it up. As much as I enjoy the challenge of dialing in the 4-jaw, there really is no good reason to do so when the 3-jaw is up to the task.











Here I have cleaned the OD, turned down the spigot to 0.188, drilled the center hole and milled the relief in anticipation of threading. Yes, I have the stock in the 4-jaw now and for a good reason you will see shortly.

I learned a lot about the lowly thread gauge from Ted Stoutenberg at the afore-mentioned meeting and thought I would pass some of it along for those who aren't that familiar with this seemingly simple tool.

As you can see the gauge has one outside and three inside angles that measure exactly 60 degrees. These are used to guide you while grinding threading tools, as well as while aligning the tool to your part. I've only got one of these, so used a little Photoshop trickery to show both sides at the same time.






Additionally, there are four pitch scales and a chart that tells you how deep to cut the threads, times two, or the overall diameter reduction to plan on while threading. While not every thread pitch is covered directly, simple math lets you sort out the ones that aren't. For instance, I will be cutting a 10-32 thread on these parts and while there is a scale for 32 tpi, there isn't a listing on the chart. No worries, as it does show 16 tpi as being 0.081. I just divided that by 2 to get a combined thread depth of 0.0405, so 0.0203 on the dial.

This is a pretty small part so getting the thread gauge in place to check its alignment against the stock wasn't going to happen. Instead I got all clever and aligned the back of the tool with the turned stock. Unfortunately, when I went to check it with the gauge it was clearly out more than I wanted. 






I then realized that I don't need to align it to the part. The lathe bed is also parallel to the spindle and could stand in. I used a soldering clip to hold the tool parallel to the bed while I adjusted the tool post.  A2Z CNC Quick Change Tool Post, in case you were wondering.






Finally, here is the cross-slide dial set to 0.020 before the zero to give me an obvious stopping point.  The adjustable handwheels on the Sherline equipment are a great feature that in this case saves having to end a thread at 0.027, or some other nonsensical number.






I am not going to cover the Sherline threading attachment here since you can read the manual online if you really want to know how it works. Basically what you do is remove the motor and put a hand crank on the main spindle. A variable set of gears ties the Z-axis leadscrew to the spindle and lets you cut consistent threads, given a little patience.


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## thayer (Dec 27, 2012)

First off I made a light skim cut and confirmed I had chosen all the right gears and set them up properly.






Comparing to the 32 pitch gauge shows one thread for every mark. If I were cutting a 16 tpi thread I would look for them to align with every other tick on this scale.






Here I am part way through the cutting operation and have just gotten to the relief. Basically you set a cut depth of a few thou, crank the spindle until the tool gets to the relief then back out the tool, rewind, reset the depth and do it again.






This shot shows why it is so important to back the tool out of the thread while back-winding between passes. There is enough backlash in the system that the tool tip gets kicked out of alignment while you back-wind. You can see here that the backlash amounts to about half the thread pitch as I reset the tool to the start. You don't want the tool binding in the groove. Besides, since you are turning the spindle backwards at this point the part would be rubbing against the back of the cutting edge. Not good.






This is why I switched to the 4-jaw. Threading the chuck onto the rotary table doesn't center it perfectly, missing by a couple thousands or so. Holding the stock in the 4-jaw lets me bring it into near perfect alignment before cutting the 6 flats. CNC makes quick work of this, with multiple light cuts and auto indexing on the angles. Or at least auto indexing if I program it right.






Here is the nearly finished part, ready to part off from the parent stock.


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## thayer (Dec 27, 2012)

Getting set to part off.






Not so fast, Champ! Milling that part to length and getting a nice chamfer on the threads would be pretty tough with my fingers and a file. Let's make it pretty before cutting it off.






That looks much better! Now where's my parting tool?






Once the part is nearly free, take a small piece of wire or a drill bit and thread it through the center bore to catch it as it separates. The troll under your workbench will make a quick snack of your efforts if you don't.






And here are the two finished packing nuts. I haven't made the steam chest yet, so I'll leave one in the original aluminum cylinder head for now.

Incidentally, I know some of the above photos seem out of order but they aren't all of the same part.


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## Propforward (Dec 27, 2012)

Thayer,

Not only am I very impressed by the quality of work you are doing, but your posts with your step by step pictures are exceedingly helpful in understanding different approaches and techniques for set up. Great stuff.


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## gus (Dec 27, 2012)

Hi Thayer,
You are right.One item at one session. Tried milling all three tool holders and nearly messed up the last one.
My QCTP now has 6 tool holders. Going on to make the Boring Head which will cost me a US$100 min. if i buy from the usual UK or USA vendors. Getting good advice and some previous threads from forum members. All success to your Elmers.

The some parts of the BH will be turned using my new DIY   QCTP.


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## gus (Dec 27, 2012)

No worries.The usual happenings. Misread plans or plans have fatal errors.Also good idea to check next related print to see if they tally with the part you are cutting.
Made some near fatal errors with my Firefly IC Engine soon as let caution fly with the wind.Engine now showpiece on my Nbook desk.Looking at it now.
It won't fly but no worries.Plan to make new engine  2013.


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## gus (Dec 27, 2012)

wongster said:


> Amazing work, Thayer!  I'll be following this thread since I've almost the same equipments has you.
> 
> Regards,
> Wong



Hi Wong,

My Chinese name is Deng Shi Cheng hailing from Singapore.
Wong is a Great Chinese Surname whereas mine is nothing with no great ancestors to boast off.

Gus.


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## gus (Dec 27, 2012)

Propforward said:


> Very nice. I agree with the slow and methodical approach. Take nothing for granted. All my screw ups have come from charging ahead.



Hi Propforward,

I have same problem when I got too smart. Now going on using surplus M.S.
bar stock to make Boring Head with no back up material if I goofed.
Common problem. No worries.Retirees have plenty of time.


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## thayer (Dec 28, 2012)

Here's a pretty quick bit. I knocked out the valve plate, steam chest cover and valve nut from some 1/16 K&S brass from the local hobby shop. Since the Z isn't all that critical on a job like this, I just clamped the stock to a scrap of wood that I held in the vise.

Step one, after the layout and setup, was to run around with the center drill and make a few divots. I think by the time I actually took this photo I had also chased the holes through with the appropriate sized drill bits.






This is pretty much the same thing, though this time with the valve nuts tapped. I am finding my little piece of printer roller bar makes a dandy tapping guide, see above.






Next up is making swarf. Awfully pretty from brass, despite this mystery metal giving me some fits. This was the first time I actually broke an end mill in a while. I was using the same feeds, speeds and tool as with the 360 for the nuts earlier, yet the K&S sheet got all gummy and snapped the carbide mill after only a few inches. Fortunately I had a spare and juggled the feed with Mach3's manual override and dialed the rpm around a bit by hand/ear/eye until everything was happier. Yes, there are 4 parts under those chips. I didn't bother keeping the area clean as I knew I was going to be dressing the parts a bit after milling.






I stopped the Z move about 15 thou short of breaking free to keep the parts attached to the parent stock. I then did some quick flexing to fatigue the parts free.






A pair of heavy duty scissors got rid of most of the flash and a few strokes of a fine file, followed by a little oiled 400-grit wet or dry, left the parts in the condition shown below.






Not tough, but still it's three more parts checked off the list. I doubled up on the valve nut as there was room on the stock that would otherwise go to waste and the part is small enough I don't want to bother fighting the workshop troll for it if I drop one.


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## gus (Dec 30, 2012)

Hi Thayer,

Using heavy scissors to trim off burrs and final finish with file was very smart  idea!!!! Never thought it. Would adopt the " Thayer Chamfer" method.
Here is my chamfering method on the lathe with DIY HSS chamfer tool bit. One draw back is a QCTP is a must for quick tool change.
The job piece is my DIY Cheapie Die Threader. I have 2.5------10mm. I use metric to go easy on fastener inventory.Was taught
in Trade School using Imperial. Since Singapore went Metric in 1970, BSW,BSF,BA,NC,NF etc is hard to buy.

Happy New Year.


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## robcas631 (Dec 31, 2012)

Just a quess! A jig?


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## thayer (Jan 1, 2013)

Hi Gus,  No one ever told me I couldn't cut brass with scissors, so ... It actually works really well with a thin piece of stock.

Rob, was that guess for me or Gus?

Happy New Year all.

Yeah, it's late and I should be in bed by now, but I am also a bit behind on my posting, so here goes a little update on my #33, specifically, my effort on the steam chest.

Here's the rough blank, a bit oversize. My stock was 1/2 x 3/4, so there was plenty to remove.





The first thing I did was clean up the ends. I wrote a little g-code to move back and forth in Y, while stepping over a little bit in X on each pass to clean the face. When setting up for a cleaning cut like this I position the tool near the stock, drop the spindle down so the tool tip is well below the surface and slide the stock against the cutting edge. I rotate the spindle at least a turn backwards by hand to make sure that I am actually referencing the cutting edge before I lock down the vise and set my X0 in Mach3. It isn't that big a deal on stock this thick, but on thinner material it is rather too easy to reference the tool in the flute and end up with a massive first cut.





And a few seconds later the end looks like this. As before, Note the aluminum packing material to balance the far end of the vise.





Once the stock was clean on both ends I clamped it in the center of the vise and used the endmill to reduce the faces to the final 0.250 thickness. A bit of Dykem on the face and layout with the height indicator had it ready to go in the 4-jaw for drilling. I protected the faces of the blank using some aluminum scrap, but the stock is still wider than needed so I have some "factory-original" padding that I can grab on the sides. The indicator is referencing a piece of drill rod that I chucked in the lathe and turned to a 60 degree point. I gave it a clean shoulder at the same time to keep it concentric with the tip and provide an accurate surface for the indicator to reference. The other end is center drilled so I can position it between a live center in the tailstock and the block to center up the hole for the valve rod and packing nut made earlier. Centering at this point isn't critical, but I still clocked in the 4-jaw as accurately as I could using this rod and the indicator mounted to the cross slide.





Once I had the stock centered, I deep drilled it with a #41 drill for the valve rod. That actually requires two drills as the main rod is .086 for most of its length with the very end at 1/16 where it references the far end of the steam chest.





Elmer also calls for the 1/16 bore for the rod to be "close" so I drilled the last 1/4 inch at .059 and then reamed it to 1/16.





Next was the #21 tap drill for the packing nut ...





... followed by the tap.





Next I moved the chuck to the mill and wrote another little "back and forth" code that dropped the Z on each step to remove most of the stock around the threaded spigot. The target line is the top most obvious layout line.





Almost half way down on the first side, as seen through the chip guard.





And with both sides roughed out.





Here I'm starting to turn the spigot.





And chamfering after turning it down to final dimension.





The other end needs a spigot for the end of the valve rod, so I flipped it around in the chuck, clocked it back in with my indicator and tipped rod, and again, wasted away most of the stock with the mill before turning it down. The center hole on this end was much shallower, so I didn't have much to turn off.





This end gets turned round, so I roughed it down with a Mark 1 eyeball chamfer and then...





... got busy with a file. What I didn't do was read the print properly. The actual diameter on that end doesn't matter but Elmer intended it to finish at 3/16, not the 1/4 I left it at here. After I finished the entire part, and realized my oversight, I went back and reduced this a bit more. And then filed the end round again. You will see the smaller dimension later.





Thinking I was done with the turning at this point, I pulled it out of the chuck and moved back to the mill to drill the mounting holes.





Remember how I said I can be a bit chicken at times? Here is one of those times. I referenced the steam chest location with my stop, then swapped out the part for a piece of wood to test my g-code for the inner pocket.





Apparently I am still living clean enough. The test looks good and aligns with the layout on my block, so that only means one thing.





Yes, time to be a chicken again!  I couldn't help myself and made a first pass on the pocket at .001.





That looked good too, so it was time to go deep. Here is the valve pocket milled through and just showing the hole for the end of the valve rod.





Everything looks good in the end. I've now also cleaned off the extra width and turned the rounded end smaller.


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## thayer (Jan 4, 2013)

Well, if you have a steam chest core with a valve, valve plate, nut and cover, it must be time for a valve rod to drive it all.

Here I am roughing out the 1/4-inch stock using a sharp HSS tool and a live center. I ground the tool specifically for this project and it is holding up well. Getting that right end down to a useable dimension is tough with the center right there. On some projects I'll rotate the tool a bit and cut backwards though here I had enough excess stock and just worked as close as I could with the angles shown. 
	

	
	
		
		

		
		
	


	




Doing some backside cleanup with a rounded finishing tool mounted in my compound slide. It is tough to see but I like the flexibility that slide offers.










Here I am trying to get as close to 1/16 as I can on the pin end of the rod using my finishing tool. I did okay on this one. In the end it mikes at .0623 with a nice finish. I'm afraid I've overshot enough to know it was more luck than skill.





The rod is rather flexible for single pointing a complete thread and I still don't trust my math on threading. I don't have a follower and didn't want to make one up, so I got it started with a sharp tool then cut the flared end off to finish it with a die.





I started the die in the holder now pushed back to the right, then let it spin fwd as the holder wasn't deep enough to accept the pin. 





The pin end was a bit long to the drawing as well, so I used my steady rest to trim and smooth the end to length. It may be within a few tenths of the right diameter, but it is now .040 too short. Drat! That will still work out though, as near as I can determine. I may end up lengthening the eccentric rod a little to make up for it.





The other end needs a 1/16 slot to make up with the eccentric rod. I pulled the rod from the chuck and moved to the vise on the milling machine. The rebate in my vise jaws were perfect for this hold. I predrilled the ends with an #50 drill.





Pre drilling the ends gave a lot of relief for the 1/16 end mill as I then plunged at the ends .010 for each pass back and forth. I used my edge finder on the smaller turned section to find the center.





After slotting I used a little more back and forth code to face the sides parallel with the slot. I think I took .003 off on each pass on the sides. The total reduction is only .015 per side so it really didn't take long. 





This next setup has a lot going on. Most obvious is that I needed to rotate the rod 90 degrees to cross drill it for the retaining pin. I already know where the slot is, so how to do that without losing my x reference? Well as you can see, I used my work stop against the rod end. I know that's an easy and obvious solution, but for us beginners it usually only comes with the hindsight afforded by a quarter turn CCW on the vise screw. The shank of my 1/16 bit is a close fit in the slot and allowed me to ensure that I rotated it accurately. Finally, the edge finder comes back into play to accurately locate the center of the flat face. You can't assume that the part is concentric with the parent stock since I used a 3-jaw to turn it. 





The hole is located plenty close enough for my eye. Elmer calls for a close dim here, so after drilling a few thou under, I ran it through with a 1/16 reamer.





Back to the lathe now, and I went right to the 4-jaw so I could dial it in closer than I can get with my 3-jaw. That really wasn't necessary, as I really was only parting it off of the parent rod.





Once it was clear I used a 3/16 collet to hold the head while I finished the rough end. I took very light cuts as I was working into the slot and didn't want to muck it up.





Here are the results, along with the pin that I will detail below.


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## thayer (Jan 4, 2013)

Since the valve rod pin is shown above I certainly can't pretend it isn't done and go to bed at a reasonable hour, now can I? Nothing to do but carry on.

The parent stock for the valve rod is still in the three jaw, so let's make the pin from a little further on down the same.






Roughed out to final diameter on the pin and head, left long for parting off and cleaning.
	

	
	
		
		

		
		
	


	




Off to the vise to cross drill. As above, the edge finder, my micrometer and a few buttons on the calculator let me find center on the rod.





Might as well skip the math and just use the valve rod to ensure adequate clearance on the hole. Elmer calls for a #70 drill here, but the closest I come with the mini carbides is #74 @ .0225. Still plenty of room for a strand of copper wire, so I'm off to the races. 
	

	
	
		
		

		
		
	


	




I learned my lesson above and returned it to the 3-jaw after cross drilling. Note the reference Sharpie mark on the stock. It's tougher to see, but there is also one on the jaw face, made at about the same time. That's close enough for parting off.





Note here that I have also shortened and dressed the end outside the hole. Yes, the lathe was spinning for this shot, but I did back the tool off a few thou to avoid rubbing.





Here I have reversed it in a collet to dress the head. Must have been close on this diameter as well, as it cleared the reamed hole in the valve rod and was a light finger-press fit in the 1/16 collet.
	

	
	
		
		

		
		
	


	




Everything needs a bit of a bath, but here it is, installed with enough room for a thin washer.
	

	
	
		
		

		
		
	


	




Yeah, that's the packing nut screwed into the valve chest.  What's another few minutes, since we are on a roll?


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## thayer (Jan 4, 2013)

All the valving / steam chest bits waiting for a home.





Coming together...





And on the cylinder block.





I agree, the oversize washers and SHCS look awful and they will go away. I made my first 2-56 test nuts today from some 1/8 hex stock and they look pretty good. Do you see any issues with making studs from 360 brass to match the heads and nuts, or should I go to 12L14? As much as I could try to justify a low-time guy like myself using Du-Bro's threaded rod, I don't think I can bring myself to do it. 





Yes, I know there is no way to get steam into the chest yet, but that will wait until I decide if I want to come in through the chest proper or its cover. Okay, the chest does make the most sense, since an engineer would want to be able to set the timing without undoing the feed. So now that I have sorted that out, it will just be a matter of where/how to feed it once I assemble it all.

Good night, all.


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## thayer (Jan 16, 2013)

Well, I am back on Elmer's #33. I have been rather busy the last couple of weeks getting a new charitable business off the ground. It's not really relevant here, so I will just mention the URL in case you are interested, http://www.ribbons4sandyhook.com 

Now to get on with the machining. I've not got a lot this time, just the piston and piston rod. Still, that's two more check marks in the done column.

The piston is pretty straight forward turning, so I will mention just a few things to go along with these three photos.

First I chucked up some half-inch stock using the indicator to get it as near to perfect as I could. I gave it a little polish with some scotchbrite before cutting the three oil grooves. Next came spotting the rod hole with a center drill, drilling and finally tapping for the rod using the tailstock chuck to hold the drills and tap. I have since learned that the best procedure is to leave the piston a few thou proud, add the grooves, and _then_ turn it to final diameter. This cleans the burrs left by the grooving operation. My stock was already at size, so I guess I should have swapped the scotchbrite and oil grooving. Next time...





The next tip I have concerns aligning the parting tool. If you have a nice clean face on your stock, why not take advantage of that "mirror"?  This first image shows the tool up against the piston, and clearly misaligned.





Here you can see the cutoff tool is now parallel with the face of the piston and is certain to give much better results.





One last point of interest on this is that the apparent angular difference between the cutoff tool and its reflection will be twice the actual error.


Moving on now to the piston rod, I lopped off a piece of 3/32 stock using a humble, yet oft-used tool. These Made-in-America cutters are great for small diameter rod stock. They are designed for cutting hardened music wire, so our typical stocks won't stress them at all. I got mine from Stevens AeroModel, http://www.stevensaero.com





I first chucked the blank in my 4-jaw, again indicating as best as I could. We want the rod and piston concentric, so don't skimp and use the three jaw.





After turning a sufficient bit on the end to 0.086, I single-pointed about 80-percent of the thread depth, ... 
	

	
	
		
		

		
		
	


	




... then finished off with a die held in Sherline's adjustable tailstock die holder. 
	

	
	
		
		

		
		
	


	









These are the finished threads for the crosshead end of the piston rod. I then reversed the rod in the chuck, reindicated it and repeated to thread for the piston.





And the assembled combo.





I don't know how true these need to be, but with the rod indicating a TIR of less than a needle width, the far end of the piston shows a TIR of just at 0.001. I have to believe that will be close enough.

Note that I've mucked with the design a bit and needed this slightly longer piston rod. The "frosting" on the piston comes from fine lines caused by pushing it back and forth a bunch by hand with the previous "short" rod.

Thayer


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## vcutajar (Jan 16, 2013)

Hi Thayer

Love your step-by-step guide.  This is helpful.  Also love your photos.  Veey instructive.

Vince


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## thayer (Feb 18, 2013)

*The Evolution of an Engine*
While I haven't posted in about a month, I have been slowly picking away at the engine. There hasn't been too much progress though, as I couldn't resist the urge to muck around with a perfectly reasonable design and to put a bit of my own stamp on it. Inevitably making a change to a proven design cascades into multiple changes and consumes more time.





Elmer Verburg originally drew the crosshead guides as simple rectangular bars and then offered up two variations as shown below if you wanted to put in a little extra time and energy to pretty it up a bit. He built his own engine with the cut away straight arch as shown above.






I liked that look quite a bit and figured this would be a chance to take advantage of my CNC capabilities. The fourth option above was my first look at using an elliptical arch on the crosshead guide, something that would be a challenge to mill conventionally. I liked the basic concept and decided to take it a bit further.

Elmer&#8217;s original mill engine has both a base and sub base of 1/2-inch thick stock, intended to simulate the rather stout cast bases of the original engines. This all in keeping with the scale and mission of the full size inspiration. After a bit of doodling I realized that by eliminating the upper base I would have another half an inch to work with and a lot more opportunity for fancying up this build. This next image shows my first passes at the main crosshead support arch, first as a straight arch, then with a pocketed web and the first hint of some feet.





Having that extra space inspired me to envision some of the grand industrial revolution engines of the 1800s and soon I was sorting out some elaborate bridgework that might give the impression that I was modeling a much larger engine where a monolithic casting might be considered too expensive, heavy or technically challenging. In the image below my design has now moved on to a column structure with a webbed spandrel. The single flute being dictated by my smallest ball end mill at 1/16. The lower image came after the inspiration to join the crosshead guide supporting structure with the cylinder support.





The above was looking good, but I felt it too severe and didn&#8217;t know how to fix it right away. In the end I took a page from the Stuart and PM Research catalogs and opted to cantilever the cylinder.





Next up was the fluting. Should the columns have single or double flutes? That&#8217;s an easy one, since I was already making it fussy, why not make it more so?  You can also see the first indication of the column bases. Just a simple quarter round cove and a mortised pocket on top to accept the tennoned columns.





But should all columns be the same weight? Here I am trying out combinations of single and double fluting. Note the crosshead spacers are also different, as try to find the solution there as well.





In the end I decided double fluting all around and as you can see have also extended the spacing between the cylinder and the crosshead to make it feel less crowded. Also noticeable is the extension of the crosshead columns to now incorporate support for the upper slide directly. As the main structure will be milled out of aluminum I also plan to attach a steel or brass plate for the crosshead to ride on.





This was a classic case of seemingly simple changes compounding to consume an exponential amount of additional time. Almost every new version had many more options that would need sorting out. Since most of this design work happened late at night it also meant continuously finding &#8220;issues&#8221; in the drawings that needed attention before I could actually go to the mill.

Next time I will talk a bit about the programming and actual milling needed to carve these bits from aluminum. I will leave you with this little teaser though. You can see the bits of bridgework starting to emerge from a piece of aluminum plate here.







Thayer


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## bazmak (Feb 18, 2013)

Is it a jig for drilling the ports ?BAZMAK


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## bazmak (Feb 18, 2013)

Yes i see it is.Very impressed with your workmanship at small scale level.
When i built a 31/2 G loco i just bandsawed a piece of hardwood for drilling the steam ports
but i took the easy route and bought castings.No CNC but the overall picture is the same
Congratulations on your posts. Very informative BAZMAK


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## Gerry Sweetland (Feb 19, 2013)

Hi Thayer,
just found your build log.  Your step by step is indeed very nice and that Sherline kit sure does nice work with you behind the wheel 

Your cylinder assembly looks fantastic.  Looking forward to you working on your design changes to come.  Nice CAD work too.
Gerry


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## vascon2196 (Feb 22, 2013)

Amazing...how did I miss this build!


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## thayer (Mar 10, 2013)

This is a busy time of the year in my schedule. What with a trade show, Pinewood Derby and a 20+ year commitment to an annual charity event, my shop time has been pretty limited recently. I have made some progress though. Here are a few photos of milling the bridgework.

First up is a test shot from a piece of wood. It only costs a little time and finding errors here is a lot easier that in metal. It looked good so I bookmatched the file and output it again for another go in aluminum.





A trusty Jolly Rancher wrapper comes in handy while setting Z0 on the stock. Note the A2Z hold down clamps. This operation is for spotting the holes for 6x 6-32 SHCS that I used to hold it down while machining.





Here is some of the early milling. The 1/16 ball end mil was first, setting in the flutting. Now for profiling with a 1/16 end mill.





The basic texture was completed with a 1/16 end mill. Now to cut it free from the raw stock with an 1/8 end mill.





Part way through. This section makes a good mess, so keep the coolant flowing. I used denatured alcohol in a spray bottle. A bit expensive, but it really helped keep everything cool.





The first side and profile are complete. Now to swap it and mill the second side.





Here you see side #2 getting started. In an ideal world I would have used a pair of close-fitting pins to register the stock when I flipped it over but the half dozen SHCS did the job well enough.





The final part rough from the mill.





Here I&#8217;ve separated the two halves, cleaned up the ends and have now mocked it up using the cylinder assembly.





Back to the job at hand. Here I am drilling the column ends &#8230;





&#8230; and tapping them for the 2-56 studs, yet to come. A small stop screwed to my vise makes an handy reference for locating the second piece.





With the holes centered and tapped, I milled a tenon on the ends of the columns to reference the feet/caps to come. 
	

	
	
		
		

		
		
	


	




Here are feet being milled from some 1/16 sheet stock. First the half round with a 1/16 ball end mill to create the cove, followed by a 1/16 straight end mill to create the mortise, clearance for the studs and finally, to define the perimeter.





I cut a couple tests, reprogrammed a little to retain them on one side, then ran the 10 that I need.





All up to date, here is how it looks now. The cylinder assembly and bridgework is secured to the base.






It is good to be back on it. I have the bearing supports drawn and will be milling them in the next few days.


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## Philjoe5 (Mar 10, 2013)

Really fine work Thayer.  Thanks for the excellent photo documentation.

Phil


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## canadianhorsepower (Mar 10, 2013)

no word to explain this
:bow::bow::bow::bow:


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## thayer (Mar 18, 2013)

Moving on to the bearings, it made sense to continue the theme that I established with the bridgework so I sketched up some pretty curves and pockets in Graphite. D2nc does support pocketing, but not yet islands, so I had to do a bit more drawing in Graphite to generate the tool paths before exporting the DXF.  These parts are pretty small, so it wasn&#8217;t too tough to sort it all out. I also did a bit of manual coding after converting the DXF to G-code in D2nc to create some custom ramping and retaining tabs. Yeah, I know D2nc now supports ramps and tabs, but I have only just recently downloaded the latest version and I am not yet up to speed with it.

This first image shows a piece of 3/8-inch stock secured to the tooling plate I made up when milling the bridgework. I first clamped the stock down and dimpled it with a center drill to mark holes for the hold downs as well as the center two which will ultimately accommodate the main shaft.





I&#8217;ve mentioned previously that I am a bit of a chicken at times and here again I am making just a light skim cut, taking off .002 with a 1/16 end mill to confirm that all looks well before committing to the full depth.





Since it looked so good with a skim on the pockets I switched to a 1/8 end mill to trace the outlines. Yes, the paths overlap a bit at the bearing heads, but they don&#8217;t interfere in the actual parts.





The test skim looked good, so here I am committing to the pocket on the outboard bearing. I am cutting at 10,000 rpm, 30 ipm, with a .010 DoC. You can see the island starting to appear in the pocket. I am using denatured alcohol in a plant misting spray bottle to remove chips and keep everything cool. It also does a great job of removing the blue dychem.





Both pockets are cut and with the test outline trace you can see pretty well what these parts will look like. The elliptical islands will be hollowed out shortly.





And here we go again. I flipped the stock and am now pocketing the other side.





Once the pockets were done I switched to the 1/8 end mill and am now opening up the islands. Why is the cutter in the midst of the pocket? I took advantage of the long axis, ramping lower into the stock while traversing the ellipse after each circuit.





All clear in the holes, so now just the perimeter to do.





Thayer


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## B-Train (Mar 18, 2013)

Luv that thread...  An high quality one, with very good quality pics + it demystifying things for the ones that never see a casting kit.  Congrats and thanks for sharing! Maybe, as you're saying yourself, not an expert machinist (I'm far to know enough for judging ) but for sure a very good teacher!


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## thayer (Mar 18, 2013)

B-Train, thanks very much for your kind words. I've always fancied myself something of a teacher, so it is encouraging to know that I may not be far off the mark.

Continuing on from last night&#8217;s post, and still with the 1/8 end mill, here I am well into outlining the smaller bearing.





Both bearings are now outlined. I left a couple .030-thick tabs on each part to keep them in place. 
	

	
	
		
		

		
		
	


	




I flexed the pieces free of the parent stock, then trimmed and filed away any evidence of the retaining tabs. Here the smaller bearing is held inverted in the vise using 1/4 lathe tools as parallels. Be sure to mic a handful of tools to find a good pair. I was surprised at how much they varied.





I next drilled and tapped for the hidden retaining screws. Note that the left hole is finished and taped while I am only now starting on the second hole. No point in changing the setup until all operations are done for a given location. Yes, I did rotate one of the lathe tools after the above photo. I realized I had positioned wrong right before I started drilling and tapping.





And here is the engine with the rough bearings in place. There is a bit of work to go yet on these pieces but I had to try them on for size. I like this view and how it shows off the overall lines. I will definitely be contouring them a bit on the faces so they are not so planar. I will also bore them for bronze insert sleeves.





Full disclosure? What I don&#8217;t like is the slight gap under the closest edge of the bearing sitting on the base, thanks to the business end of my 2-56 bottoming tap which is still in the part. The bearing is currently sitting in a solution of Alum, simmering away. I could have just remade the part pretty quickly, and fully expect to do so anyway, but I wanted to give chemistry a chance first.

This view also highlights the need to flute the end faces of the bridge columns.


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## vascon2196 (Mar 19, 2013)

Nice!!!!!!


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## thayer (Mar 19, 2013)

Thanks Chris, alas though, not any more. At least for now.

When we last left the shop I had a pot of alum solution simmering away with a broken tap encased in partially milled aluminum. I nipped on down to give it a check right before turning in last night and decided the 12 hours it had seen so far was close enough. So, how did it all turn out?

Well, not quite as I had hoped. When I opened the lid there was a peculiar odor and a faint stream of bubbles rising from the offending area, but there were stronger streams rising pretty much everywhere else. I don't know if I had it too hot, too concentrated, or what other parameter was off, but as you can see below, I made a proper mess of the entire part. The tap was in the larger hole to the right, and in fact a good part of it still is.






I've been doing a bit of redesign on these parts since milling them anyway, so I'll start on a new set next time in the shop. Once I saw them I decided they were a bit "monolithic."

Thayer


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## vascon2196 (Mar 21, 2013)

Good for you for trying to get the broken tap out....I tend to throw the part across the shop when it happens to me.

It doesn't get the tap out but somehow I feel better afterwards.


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## canadianhorsepower (Mar 21, 2013)

> Well, not quite as I had hoped. When I opened the lid there was a peculiar odor and a faint stream of bubbles rising from the offending area, but there were stronger streams rising pretty much everywhere else. I don't know if I had it too hot, too concentrated, or what other parameter was off, but as you can see below, I made a proper mess of the entire part. The tap was in the larger hole to the right, and in fact a good part of it still is.


 
your doing nice work man , as for your aluminium getting like this are you sure their was no sulfuric acid close by???
I did use this method alum  on aluminium and never encounter this but I always did it in the open not with a closed lid


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## thayer (Mar 22, 2013)

Luc,

As for the acid, none that I know of. I mixed up the alum in a small pyrex bowl, placed it on a coffee cup warmer and used the next bowl size up as a close fitting cover to control evaporative losses.


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## canadianhorsepower (Mar 22, 2013)

thayer said:


> Luc,
> 
> As for the acid, none that I know of. I mixed up the alum in a small pyrex bowl, placed it on a coffee cup warmer and used the next bowl size up as a close fitting cover to control evaporative losses.


 

Ok when i do it I just let the water evaporate and I'm adding some little
at the time to compansate
weird
I would put it back in the solution (no cover) and let it run more just to
see if the aluminium would still bubble:fan:


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## thayer (Mar 22, 2013)

I might do that with some scrap at some point. The original solution is now gone though so I will be starting anew.


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## thayer (Apr 18, 2013)

I'm not dead yet!

Wow! I just realized it has been a busy month since I last posted anything on this build, and nearly three weeks since I touched the drawings for the bearings. One the one hand, the drawings are just as I left them, on the other, It has been long enough that I am not sure I know what I drew! A bit of cogitation should bring me back up to speed rather quickly though.

The last month has been rather interesting as my wife knew a local widow who's machinist husband passed last fall. He spent the last 50 years of his career working out of the house so there was quite a bit to sift and sort. His Bridgeport and South Bend lathe are well beyond my means, but his grandson, also a machinist, has been very generous in letting me pick through the remaining stock for well under market value before the scrap dealer carted it all off. I doubt I will be buying much metal in the foreseeable future, regardless of what I tackle next! A storage system for all the stock looks like the logical next project.

I also picked up a band saw, die filer, shear, brake, one-inch belt sander and quite a few endmills, taps and drills. The shop is getting crowded but I am a lot better equipped than I was the last time I checked in. The best part though, has been the lessons. I've been firing tons of questions at the grandson and learning a lot about materials and tools that will work for me. I almost feel like I have served a minor apprenticeship!

Anyway, just a quick note to let you know that I have not abandoned my build.

Thayer


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## thayer (May 1, 2013)

Finally, some good news.  Not great, just good.

I'm prepping the photos now, but in case I don't get to posting them tonight, we finally have a reasonably successful cut on the bearing supports! It was a marathon with a lot of setbacks, but in the end I will be happy with them.

More soon.

Thayer


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## thayer (May 2, 2013)

Well the photo processing went faster than I expected, quite the opposite of milling these parts!

No question, the bearing supports have been the largest single contributor to my scrap bin to date. You know that old saying "the third time is the charm"?  Yeah, well that one fits somewhat, but not "to a T."  This time it is more like "the fifth time is the charm," and even then I'm not completely happy with what I have. Despite the transient frustration though, I am still having fun. And in the end, that's really all that matters, right?

So let's get to the progress, such as it is. Just so you don't have to go looking back, here is what my setup looked like on my early attempts. Just a piece of plate stock secured to the tooling plate first used for the main bridge work. I was cooling and clearing chips with a mist bottle filled with denatured alcohol.






The problem with that approach was the mess that got left behind after milling awhile and the constant attention required. Not to mention the rate at which I was going through the denatured alcohol. The gray surface you see to the left does keep the chips off the y-axis ways, but they manage to get just about everywhere else.





Milling the bearings takes right around two hours of machine time, so I decided to try an idea for cooling containment that I have been tossing around. I got a deep foil lasagna pan at the local grocery store and as you can see below burnished the pattern flat where my tooling plate would sit to help seal it between the tooling plate and table. I just used a pencil to poke a couple holes for the plate hold down screws. The plate is not yet secured in this photo, just resting in the pan.





I counted on a reasonable seal in the sandwich and in truth that seemed to play out as planned. When I removed the pan earlier this evening only the faintest amount of alcohol had weeped through to the table.





The milling sequence followed much as described previously, so I won't bore you with repeating that all. Below is a moment of great frustration though. Every once in a great while my y-axis stepper will make a gravely noise at start up and not respond, maybe once in every 50 or 60 power cycles. It has never faulted while running though, so I never thought much about it. That is, until I was 10-12 minutes from the end of my fourth attempt at milling the bearing supports a couple days ago. Things can go wrong with CNC pretty quickly. There was only something like 2 seconds between the failure and when I pressed the e-stop panic button. Regardless, that was still plenty long enough to cancel two hours of milling as the end mill drove through the lower flanges of the major bearing support.




I had hoped to salvage the minor support, but even that one was doomed on this attempt. My specified retaining tab thickness wasn't all it should have been and they flexed just enough to catch the part on the tool right before finishing. The resulting scars were motivation to scrap it as well. 

Here are the final few moments of the fifth round of cutting, this time with thicker tabs. You can see that I have now abandoned the mist bottle and rigged a rudimentary gravity-fed flood coolant system. A pencil hole in one corner of the pan transfers the used alcohol to one of a pair of plastic deli bowls that I am using to transfer it back to the source container. The system works well, and the constant attention required previously with the mist bottle has been reduced to only near constant. Yeah, a filtered transfer pump is on the shopping list. Any leads? Anything close to 1gpm flow should be fine.





Here are the parts still in the parent stock and you can likely see the problem in the lower end (right side) of the oval of the smaller support. The oval is not supposed to intersect the lower flange. A chunk of aluminum off-cut got caught against the tool and wedged it into the part. Drat!!!





When I saw the first parts a month or so ago I felt they were too "blocky" and begged a bit more refinement. Here you can see how a slight taper helps out the minor support that is ultimately positioned on the raised base and supports the main shaft between the crank arm and eccentric. I decided to bore the bearing holes on the lathe faceplate, so did not drill them at all before milling. The horizontal slot lets me know how much stock to turn away, yet still gives me a reference surface coplanar with the foot so I can accurately secure it to the faceplate.




This view also shows off the scar at the base of the oval. I am considering milling out the offending area and having the oval be open instead of making a new part.

The side view shows off the tapering, as well as the radiused profile of the actual bearing area. Remember most of that will be milled off, leaving a more subtle contour. The support is not sitting flat as I have not yet cleaned all of the retaining tabs. 





By comparison, here is the profile view of the major bearing supports with the redesigned part to the left and original to the right. As this support will sit outside the flywheel and not between two components like its smaller partner, I tapered it only on one side. Both supports will have the same head thickness when finished.





This is the show side that will be most visible once the engine is assembled.





Here you can see the back side that will be against the flywheel. The shallower pocket on this side is due to my centering the flange under the offset head. The dimple at bearing center is designed to help me align the support on the face plate for boring. The minor support has a similar dimple on its reverse side as well.





So there you have it.  Six weeks or so of free time wrapped up in one good part and another I might still be able to salvage. And yes, I have laid in a supply of 2-56 taps. Hopefully one will be enough.


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## thayer (May 2, 2013)

One thing I realized last night after posting was that between the good and nearly good parts I could make a save on the smaller bearing support by doing actual split bearings. Hadn't expected to do so, but who knows what depravity will infest my mind before I am done.


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