Elmer's no 29

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Johan Maritz

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Hi, i have recently more or less completed Elmer's no 29 engine. It has been quite a difficult journey. On first impressions it looks rather simple and easy. Not so for me anyway. Most of the parts is seriously small and as Joe Pie mentions, you can't machine what you cannot hold. You do not want to know how many parts i made a couple of times because i painted myself into a corner. I even had to brush up on my math getting the cylinder ports machined correctly with the correct angle. The Flywheel was a project on it's own and still need some tidying up. Again the tapered spokes with Marv Klotz's programs. I have run it on air and will soon load a little video of it running. I just do not have an elegant air connection yet. I have deviated a little here and there to make the engine more attractive. Quite expensive being mostly out of brass. I did not polish it with Brasso, only sanded all parts with 2000 wet and dry. You will notice I run out of m2 nuts, can't find any over here, i will probably need to make some. I battled to take good pictures, i have a nice camera, but i just could not manage any good photos. The focus and field of depth is tricky. In the end i just used my phone. You will see a vertical boiler is in the planning. That is a new world for me. Will see how it goes.
 

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ShopShoe

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You did a nice job on that. I like all of it. I think your photos are fine.

I'm also looking forward to the video.

--ShopShoe
 

cwelkie

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Very nice engine! It is one of the more challenging "Elmer" designs and yours looks good. I'm sure it will run nicely too.
 
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Hi Johann. A lovely looking model! Well done. Does it run nice and slowly on air?
I didn't make a copy of Elmer's or other, but made a "simple" table engine - mostly in steel. I used a single crank and con-rod to a cast top cylinder cap and guide for the piston rod, scotch yoke linkage from eccentric to valve rod. A bit tatty, as my paintwork is not good.... but it runs nicely... I hope to see yours running soon?
If you want advice re:boiler making, just ask... I have confused many by blinding them with Engineering!
The simple issue, is that an engine takes a lot of precision machining, etc. and assembly, to make a pretty safe and pretty model... But a boiler looks like a simple job to make, yet when pressurised contains a LOTS of stored energy, that will hurt people if ANY THING goes wrong. It is very hot (burns, and pain), probably uses gas or wet fuel for flames (fire risk, explosion risk), and if the steam does not go where you want it to go, e.g. If a pipe leaks, or joint cracks, then the invisible steam can literally cook flesh on the bone! Boilers are also Regulated everywhere "public".
If you are making a proprietary design, check the design calculations comply with latest regulations, and get your club expert boiler maker to witness your home made parts, for compliance against the design, fit, materials, etc. before silver soldering. He will then be in a happy frame of mind when you ask him to examine your soldering and witness hydraulic tests and steam tests before issuing a certificate.
If the design is your own, tell be what material sizes etc you plan, and the basic design, and I shall give you my humble opinion. No obligation, just so you know and can be happy and feel safe.
K2
 

Johan Maritz

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Hi thanks to every ones kind comments and advice. Something that i forgot to mention, it is one thing machining all these tiny parts, it is a completely different thing to fit all these together and to get it to turn with the least possible friction. Thanks Steamchick for your willingness to check the boiler specs, I know that is an animal of a different kind. I will use an approved design, but closer to the time consult this group.
 
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Hi Johan, Noted.
For your further appreciation (and anyone else who is interested?): Just be sure the design is up to current standards for your Nation. I have recently de-rated some boilers from "traditional UK" to latest ASME regs limits (I have not found better) so the altered Safety valves and NWP are now OK. E.G. One was changed from 45 to 20psi NWP, another from 60 to 45psi NWP. But a few other boilers were OK without adjustment of their NWPs. - These were "Home" designs, not from "1920s" book designs.
The significant "modern" changes are:
  1. that ASME limits Silver soldered boilers to 100psi, due to soldering material properties at elevated (steam) temperatures.
  2. ASME de-rates the permissible Tensile strength of Copper due to the elevated temp at steam pressures.
  3. A blanket "stress concentration factor" of 3.3 must be applied to the hoop stress where there are any penetrations in the walls of cylinders. - Even if reinforced.
  4. I have researched and deduced that a tube in compression - due to steam on the outside and atmosphere on the inside - can only withstand a max. of 21% of the permissible tensile stress for that temperature (of steam at pressure).
The de-rated boilers were affected due to factors 3 and 4 above. (Fire-boxes with fire-door holes, and fire-tubes with cross tubes!).
All these are factors "ignored" (Probably "not known"?) in most model boiler-making books. But as "model boiler designers" are apt to over-design their boilers, many boilers are strong enough for latest engineering ideas, anyway. But, notwithstanding, check, check, check, to be sure to be sure!
K2
 

Johan Maritz

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Hi, I eventually managed to record a video of my engine running. Forgive me my movie making skills is very limited. My air supply was difficult to control nicely, i need to make myself a valve or regulator of some sort to control the airflow to the engine. It runs fine at this stage, you will notice i run out of M2 nuts, i will probably have to make a few.

Elmer Verburg # 29A

Elmer Verburg # 29
 

ShopShoe

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Johan,

You have made a very nice version of #29. Your video is fine, and it shows that your engine is running smoothly and consistently.

Thank you for posting,

ShopShoe
 
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I just looked in the mirror, saw a few missing nuts, but things still work fine!
Well done on a nice model.
On my similar table engine, to get it to run slower, and more evenly, I added some weight opposite to the big end, so it has an even up-stroke and down-stroke. Otherwise, it is doing some work lifting the piston, rods, etc. before regaining the energy and a creating when the parts drop. Should run at about half-that speed..., mine runs around 5 psi. But is nowhere near as pretty!
Well done!
K2
 
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Johan Maritz

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I will look into counter weighing the crank, it makes sense to me, and can indeed make it to run smoother. That is an easy part to redo. Thanks for the advice. Mine was running at a minimum of about 36 kPa, not sure how much PSI that is.
 
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Hi Johan, 36kPa is about 5 psi.... and yours runs faster than mine, so will idle on less when you get a throttle and balance the flywheel!
Excellent work!
I said mine was not so pretty - here it is... (different arrangement of linkages to yours - hidden in this view).
K2
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Johan Maritz

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Thanks for your kind words. I really appreciate it. It felt if i would never complete this engine, i made several parts a second time, i had to make several jigs to help with the small part holding. I sort of " painted myself into a corner" with quite a number of machining sequences. After a while i started making notes first as how to proceed with the steps without losing concentricity. That was a good learning curve for me. I still have the opinion that a model engineer must be able to do some serious math calculations. I made the piston of good old cast iron. Things like the flywheel was almost a days work, i wanted to do it exactly as per the drawing with tapered spokes. That alone was a challenge. I used Marv Klotz's calculations to do that. Now that alone was a new mission getting to understand his program and getting it to run on a"Dosbox" application loaded into Windows. Anyway a long story short, his calcs works really good and i use a lot of them. I tried to hone the cylinder bore as good as possible for practice, as i want to try the David Kerzel engine as a first internal combustion engine.
 

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Richard Hed

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Thanks for your kind words. I really appreciate it. It felt if i would never complete this engine, i made several parts a second time, i had to make several jigs to help with the small part holding. I sort of " painted myself into a corner" with quite a number of machining sequences. After a while i started making notes first as how to proceed with the steps without losing concentricity. That was a good learning curve for me. I still have the opinion that a model engineer must be able to do some serious math calculations. I made the piston of good old cast iron. Things like the flywheel was almost a days work, i wanted to do it exactly as per the drawing with tapered spokes. That alone was a challenge. I used Marv Klotz's calculations to do that. Now that alone was a new mission getting to understand his program and getting it to run on a"Dosbox" application loaded into Windows. Anyway a long story short, his calcs works really good and i use a lot of them. I tried to hone the cylinder bore as good as possible for practice, as i want to try the David Kerzel engine as a first internal combustion engine.
I am working on an ER set which will attach directly to the lathe nose, a D1-5 with six pins. I am in a similar situation as you when you say you painted yhourself into a corner. I already made one but it does not have good reproduction when taken out and replaced later. I made several mistakes, the first one was not having a mill to accuratley place the pin holes. My pin holes are misplaced by a tiny amount which I located, punched then drilled with a sloppy drill press. I figured I only needed 4 out of the six pins as work with ER chucks are rarely heavyduty. So, now that I messed up that, I still have room for a second try on the same chuck. If that doesn't work, then I'll try something else.

Now I am considereing my direction of operation. 1.) make the round disk, 2? drill the pin holes or cut the nose recess? Either one of these creates problems for the other operation. So the problem of not having a mill created this problem. If I have a mill I would cut the recess first because I could easily center the nose recess and position the pin holes accurately and drill the holes properly.

4.) (as the last two operations were 2 and 3), weld a pre-sized cylinder to the disk. (Since the pins are a separate set of operations, use the pins to place the welded pieces on the nose. 5.) proceed to cut the ER threads and cone.

Unfortunately I am not finished setting up the mill but it should be soon (that is, hopefully before the end of the year). If anyone has any suggestions please butt in. You can be as rude as you like as I am not sure I am posting this in a proper forum thread.
 
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