Difficulty in building an Elbow engine

[substandard]

Finishing up my first engine build which was the EZ engine, and now I am looking for the next project. The Elbow engine has caught my eye and I was wondering how difficult it was to build.

How finicky are these engines to make them work? Does it require close tolerance or can there be a bit of "slop" By "slop" I mean +/- .006"

 

[Cedge]

Deceptively easy to build but can be quite difficult to get running. You'll hear the endlessly repeated words "pistons have to be perfectly square" from everyone who ever built one.

Steve

 

[bearcar1]

Hello SS, Those elbow engines are quite unique but one of their downfalls is that they require that everything be lined up and accurate to run smoothly if at all. In their inherent nature, all of the pistons, or 'elbows' as it were, have all got to be aligned at 90* lest one or all of them bind during operation. Along those same lines, if the bores in the two rotating cylinders are not a close running fit to the piston, that to will cause problems, not to mention the oil that will be spewed forth even worse than normal. To me, .006" would be VERY sloppy for that engine. One of the members here recently finished up a beautiful offering of this engine, you may want to do a search and read that build log to get a better feel for what is involved in replicating one of them. One of Elmer's wobbler series engines would probably be a better candidate for a second engine but that is just my opinion. By all means do not give up on the elbow but be aware that it doesn't have a great deal of 'forgiveness' built into it, if you understand my meaning. :big:

BC1
Jim

 

[substandard]

Hmmm... maybe the Elbow will move down my list of engines until I have some more expeirence.

Now off to look for another project... ;D

 

[SBWHART]

Hi Sub

I recently finished my second elbow engine, I built the first 12 months ago and whilst it was a runner and I learnt at lot with its build i could do bettter No 2 runs superb, I then rebuilt No 1 into a good runner.

The drawing on John Tom make it look a deceptivly easy engine to make in reality they are very dificult to build sucessfully particularly if you follow John tom drawing.

If you look her I've posted a complete build log of both engines, along with a set of drawing of a design that adress some of dificulties, pointing out some of the critical features associated with the design.

http://madmodder.net/index.php?topic=820.0

The fit of the pistons is not that critical but alignment has to be spot on along with getting everything square, and the cylinders equialy spaced on the pitch circle.

Its not an engine for a newbie, not unless you like throwing things through across the shop.

Hope this helps

Stew

 

[rake60]

Go for the Elbow Engine build!
It is a real character building experience.

I did an abbreviated documentation of my build on my personal web page.
The Elbow Engine

I also have a post here that tells how I cheated to get it to run.
My Elbow Engine - Confessions of How I Fixed My Errors
That post was so old I had to fix a few links in it.

It isn't pretty, but it sure felt good when it ran!

Rick

 

[rtp_burnsville]

Hi,
My elbow engine was the first major machining project in a college class I took years ago. I still have it today, looks crude but it will run. The guys are right that it's the alignment that will try your spirit, go for it!

Robert