# PM Research #5 "coke bottle" steam engine



## McSummation (May 22, 2018)

For anyone not familiar with PM Research's castings kits, this is what one looks like:












P1050535



__ McSummation
__ May 22, 2018



						What's in the box
					



They supply very good documentation in the form of a large exploded diagram and detail machining plans:












P1050536



__ McSummation
__ May 22, 2018



						The rest of the box contents
					




It IS a castings kit:












P1050539



__ McSummation
__ May 22, 2018



						The castings
					



and I had not seen one with multiple small castings tacked onto a larger one.  When I was looking at the machining drawing for some of these, I wondered how I would hang onto them while milling.  Now I know.

There is also some raw material, square/round/hex, brass/bronze and steel:












P1050540



__ McSummation
__ May 22, 2018



						Raw stock
					



and, of course, a bag of little bits - screws, setscrews, piston rings, etc.

The machining photos that will follow show how I figured out how to do it.  Since I am relatively new to this, there are undoubtedly better/simpler ways.  This is just *my *way.


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## stevehuckss396 (May 22, 2018)

looks like a nice project.


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## Herbiev (May 22, 2018)

Great looking kit. I'll be following along


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## McSummation (May 23, 2018)

Got the Crank Bearing Caps drilled this morning.

They were on the same casting with the Valve Chest Cover and Head:












P1050541



__ McSummation
__ May 23, 2018



						Casting holding Crank Bearing Caps, Valve Chest Cover, and Head
					




After much fussing around trying to hold the pieces such that I would not drill my vise, also:












P1050542



__ McSummation
__ May 23, 2018



						Crank Bearing Caps after drilling.
					



The ends will be milled off after mounting in the Frame.


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## bouch (May 23, 2018)

I'm about 1/2 way into mine.  Crankshaft, flywheels, cylinder/heads done.  Next up is to machine the body.  I'll be watching with interest.


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## McSummation (May 23, 2018)

bouch said:


> I'm about 1/2 way into mine.  Crankshaft, flywheels, cylinder/heads done.  Next up is to machine the body.  I'll be watching with interest.


How did you do the crankshaft?


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## McSummation (May 25, 2018)

The piston specifies a 9/32" counterbore.  Since a nut is going to sit on the bottom, it needs to be flat.  I don't have a 9/32" end mill and my boring bar won't go into a small hole like that.  So, I mounted my 1/4" end mill in a boring bar quick change, bored the correct depth, then moved the end mill 0.015". 












P1050544c



__ McSummation
__ May 25, 2018



						Using end mill like a boring bar
					



Seems to have worked OK.












P1050545c



__ McSummation
__ May 25, 2018



						Completed piston


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## bouch (May 25, 2018)

McSummation said:


> How did you do the crankshaft?



Short answer:  Between centers in the lathe.

Long answer:  I'll take photos some point over the weekend of the tooling I used.  I messed up the first one I did, so needed to get a replacement from PM.  But, that lets me bring the tooling to model engineering shows as an example of how to machine a cast crankshaft.  I can take photos of that.


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## bouch (May 26, 2018)

Now for the long answer...

1) Take the cast crank and determine the center of each end.  Mark it, center punch, and center drill both ends.  This so you can put it between centers on the lathe.
2) Take a short bolt and nut (or a piece of stock cut to fit) and put it in the gap where the throw is.  Adjust so its "finger tight".  That is, its putting a little pressure on both sides (you should file the sides to give yourself a flat surface) but you can just pull it out.  Idea is to prevent springing when you put it between centers, but you don't want to introduce and springing.  (a future photo will make what I'm trying to say this a bit more obvious.)
3) Between centers in the lathe, turn the two main shafts.  Don't take them to final dimension yet, leave them oversize.  You're really just cleaning them up at this point.
4) Make two blocks that kinda look like this:







Let me explain what you're looking at.  You have one hole which is drilled to take the axle, whatever dimension you've turned it to.  You've also drilled, using a centerdrill, at the given distance for the crank throw.  This is how you'll turn that part of the crank.  You've used a hacksaw to cut a slot to the hole for the axle (doesn't have to be pretty, just needs to be able to clamp down on the crankshaft).  Then you've drilled a hole thru, perpendicular to the slot, threaded on one side of the slot and clearance drill on the other.  Tighten onto the crank, making sure both blocks are parallel.  The extra bolt is to lock the tightening screw so it can't loosen up during machining. 

Looks like this from the side:






What you're looking at here shows what I mean by putting a bolt and nut "finger tight".  In this photo, its preventing any springing when between centers and you're turning the throw.  DO NOT tighten with a wrench, or you'll introduce springing.  You're just making a spacer exactly the distance from the end blocks to the web.  I can slide those out with a little pull.  But, you can't spring the crank with the pressure which comes from mounting between centers.  When turning the mains, (step 2) a similar, smaller bolt/nut goes in the small gap in the center of the crank.

You might be wondering if they'll fly out when in the lathe.  Nope.  When you're turning the throw, these aren't "off center", the centerline of the bolts is the center of rotation, so there's no centrifugal force on them.

5) Make two cutting tools which look like this:






This is how you're going to turn the throw.  The larger one is for rough cutting, the smaller for the finish cut.  Both sides are sharp.  You need to set it up so both ends make contact at the same time.  Easiest way to do this is to push it against the blocks at the end, with a piece of paper between the blocks and the tool.  Move the paper until you're feeling the same resistance on both ends.  If it pivots on one side and the other is loose, its not right.

The width of the finishing cut tool must be less than 1/2 of the width of the throw, so you can make a pass and both ends of the tool will go beyond the center.  That'll make sure you don't have a ridge in the center.

6) Put the crank between centers on the lathe, using the two center drilled holes for the offset.  You'll  have a fair amount of offset mass, and an intermittent cut, so you want to use a slower cutting speed.

With the rough cutting tool, cut both sides of the crank, and turn the throw oversize, but to close to final dimension.  Then put in the finishing tool and turn to the final dimension.

IIRC, I then used a "normal" tool to machine the radius on the end of the web.  Note you're only getting one end in this setup.

7) With everything still together, use the end blocks to put the crank in your milling machine and finish the sides of the webs.  (that is, the surfaces which you can't turn in the lathe!)

8) remove the blocks.  Put the spacer back between the now-machined webs.  Put between centers and turn the main shaft to final dimension.  Also machine the radius on the "other end" of the web.

When you're done, it should look something like this






I hope this helps.  If there's any part that's confusing, ask and I'll try to explain it better.


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## McSummation (May 26, 2018)

Thanks for the explanation and very clear pictures.

My crankshaft already has a spacer in the throw.












P1050547



__ McSummation
__ May 26, 2018



						Crankshaft
					




According to my "cutting plan", it's several days until I'll do the crankshaft.  I'll post my results when I get it done.


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## bouch (May 27, 2018)

Interesting.  I  bought my castings about 10 years ago, I wonder when they added that spacer.

One other point.  Grinding those cutting tools is a lot easier if you use a dremel/foredom tool instead of your 6" bench grinder....


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## TonySteamHobby (May 28, 2018)

I finished one of these last year. I broke three taps on the casting. Those tiny mounts hardened more than the thicker part of the frame. I finally drilled the holes one size larger. It is, however, my favorite engine to date.


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## TonySteamHobby (May 28, 2018)




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## KJE (May 29, 2018)

My PM Research Coke bottle engine.


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## KJE (May 29, 2018)

All the parts before final assembly and painting. You might have noticed a couple of custom pieces, the cast iron valve case cover was too hard to drill  so I made up a brass one and I made a goof on the valve linkage guides so fabbed up a couple  from bar stock. All in all an interesting project. Hope you are having fun building yours McS!


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## McSummation (Jun 17, 2018)

Work has gotten in the way of machining much.  I've done the small threaded rods and some nuts.  I've also been experimenting on how to machine the head that the piston rod goes through.  Almost ready to tackle it.

I did get the valve done.  










The "bobble" in the corner of the underside recess is due to me not remembering which direction is which on the mill.  I need to remake some labels I had which got lost when I put the belt drive on it.


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## McSummation (Jul 9, 2018)

Since it's gotten hot here in north central Texas, I've been spending time during the day working on another project - StevensAero SE5.a model airplane - http://www.stevensaero.com/product/se5a-um/

I got the pulley and flywheel done.  I did the pulley first and then had to make a longer mandrel for the flywheel so I could get on the left side of it on my lathe.  Even though my lathe is a "7 inch", 3" is about all you can turn and get to both sides of the part.


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## McSummation (Jul 9, 2018)

One thing I had been dreading was the "notch" in the valve guides.  I finally bought a 90 degree carbide tipped router bit, which made that part of the machining easy.


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## vederstein (Jul 9, 2018)

Don't worry about little bobbles.  This engine is quite forgiving even though some of the parts on the tiny side.

If you do have an issue with the D-valve.  It's small enough it can be remade in barstock.

...ved.


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## LorenOtto (Jul 10, 2018)

McSummation said:


> For anyone not familiar with PM Research's castings kits, this is what one looks like:
> 
> 
> 
> ...


I have this kit sitting on my shelf so I will be following you build with interest.


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## LorenOtto (Jul 10, 2018)

TonySteamHobby said:


> View attachment 101623


Good job.


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## McSummation (Jul 21, 2018)

Time for some "Help!"  

I'm working on the crankshaft.  The casting is so rough that I smoothed it some on my bench grinder.  Then, using a steady rest, I used my tool post grinder to grind a round section at the ends.  After moving the steady rest to the ground area, I tried to use a center drill.  It won't drill.  The end is very hard.  Have I "work hardened" it?  Do I need to temper it?

I'm also working on the frame - on the valve slide guide mounts.  Three of the holes drilled and tapped OK.  The fourth one won't drill.  Could this also be "work hardening"?


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## mayhugh1 (Jul 29, 2018)

It's probably not work-hardening. I'm not familiar with those castings, but I assume the crankshaft casting is cast iron. It's not uncommon to run into an occasional hard spot in cast iron where the carbon content wound up too high due to inhomogeneity problems or improper cooling of the melt.  Carbide tooling might might get you through it, but if it's too widespread it might be cheaper in the long run to discard the casting and make the crank up from barstock. I understand why many parts are best machined from castings, but some, especially crankshafts, aren't well suited for castings. A better quality part could probably be more easily fabricated from barstock - either cast iron or drill rod plus some bits of hot or cold rolled steel.
I just sold a set of castings for a Challenger V-8 and many of those parts would have been difficult to fabricate fom barstock. But the kit also included cast iron cylinder liners that had been cast with steep draft angles that would be difficult to chuck up for their initial turning. Even worse, the cast iron looked pretty nasty and was probably riddled with hard spots. Those parts would have been much better sourced from a short length of 1" round gray cast iron or even better 12L14 in the kit.  Unless you just want to solve the challenge of working with the casting, I'd go the barstock route. -Terry


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## AlbertdeWitte (Aug 23, 2018)

Hi There

I have also built this kit some time ago, it might be a hard spot there, drill with oil and slow speed, sharpen drill often.


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## natalefr (Aug 23, 2018)

Il n'est pas difficile de construire un vilebrequin


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## Cymro77 (Aug 23, 2018)

N'est pas difficile pour vous, mes pour moi ouch!!!


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## natalefr (Aug 23, 2018)

I also thought it was difficult, you can find many videos on youtube where they explain how it is done, here is the construction scheme of the Hupshur vertical drive shaft


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## packrat (Aug 24, 2018)

I have a full size steam engine like the one you are building, It came out of a old creamery and milk plant in Orem, Utah.
had to make a few parts for it and  was painted black and red by someone ..Have run it on live steam and air, at one time I had a boiler { a 40 HP Case } engine would run real nice on 40  psi of steam..


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## DougB (Aug 26, 2018)

The pictures of my bottle engine I built some years ago complete with generator constructed using a stepper motor. They are quite versatile  little engine, enjoy your build.

Doug Baker


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## natalefr (Aug 26, 2018)

Very nice engine !


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