Elbow Engine - epic failure but still hope!

[raynerd]

This had doomed written all over it before I even began! I saw Johns and Stews several months ago when I first got my lathe and they blew me away -  I find it really amazing how it runs and had to try one and after the success of my two little wobblers and my DRO and belt drive on my mill, I was up for anything and more importantly, in a state of mind that I knew this was perhaps a little above me and that I wouldn`t let it put me off if it did go wrong. I sound defeatist but I was just being realistic. After all, I bought a lathe several years ago and tried building a clock gear after about 2 weeks - as you can image, I soon gave up and lost interest.

Anyhow - this has taken me a good couple of weeks on and off. I knew everything had to be bob-on and so I took my time. I had all the bits I needed in scrap stock, the only thing I purchased specifically for the project was 1/4" silver steel for the pistons. I have also been using Stews build thread to help me along as well as asking quite a few questions, so cheers for putting up with a little pestering Stew.

I stuck pretty much to the plans on John-Tom, one thing that I noticed John and Stew had both changed on their builds, was to incorporate a valve port block on the vertical (flywheel) support as well as the horizontal base. I wasn`t confident enough to take this onboard as I would have had to change other dimensions and although this was an obvious alteration, I just didn`t dare stray from the plans.

Anyway, all the bits are shown below:



So I put them together and NO LUCK! It binds up right away - no movement what so ever!!! So I locked in each piston one at a time and turned it with toothpaste for about 20 mins each one    and then back together and I was thrilled to bits to find that it turns manually.

  So project complete, right? It turns manually.... 




Regards
Chris


p.s have these engine meant to turn under pressure? Only I have been trying to get it to run off the compressor for several hours and I am coming to the conclusion that it is impossible right ? 

[sbwhart]

Wher's the fly wheel 

If you've got it turning manually sticking a fly wheel on it may do the trick.

Can you spin it.

Good luck

Stew

[raynerd]

LOL oh, a flywheel!! Good point!! I saw the latest one over on "the other forum" without a wheel and presumed it would turn. I`d just totally lost the plot.....good point.

I`ll keep the project updated, I`m certainly not given up yet!! By the way, what do you mean by can I spin it?  - I can turn it manually with a little force.
Chris

[sbwhart]

I saw the latest one over on "the other forum" without a wheel and presumed it would turn.

Chris

Every engine has differences what works for one may not work for another, you may not have a free running engine but a lumpy running engine is still a great success, and I bet you learnt a lot. 



Stew

[Bernd]

I'd say you have a winner there. 

If it turns over by hand it should turn over with some air pressure once a flywheel is added.

Keep at it. I want to see it run.

Bernd

[raynerd]

I`m not talking about really having to force it around but there is certainly a little friction - how free should it be?

Chris

[sbwhart]

Chris

with mine if I give it a spin from the fly wheel it'll do a good 1/2 doz revolutions.

Stew

[raynerd]

 

No no...it doesn`t "spin", you can turn it with a little pressure and it rotates but it certainly isn`t free enough to spin. I think that perhaps my pistons are not exact enough and are therefore rubbing. It could be simply the fact that everything is out by a spidge and is causing it to bind. I`d have thought that if I was miles out in my machining then it simply wouldn`t turn at all, it must only be a smidge out. I`ve not given up yet.....! 

Chris

[NickG]

That's the first thing I was going to say, where's the flywheel! You'll be very hard pushed to get it to run without one! Sounds like you have a friction issue too though!

Great effort though, keep going you'll solve it!

Nick

[cedge]

That is the most deceptively simple engines you can build. The small number of "easy" to make parts has sucked a lot of us into the vortex of frustration when it came time to run it. My own version never ran more than a few turns at a time and I've always considered it a failure too. I am planning to revisit the little beggar now that I have a bit more accuracy at my disposal.

Steve

[rleete]

Cedge, as I recall, you stepped quite a bit away from the beaten path on yours.   (Understatement of the year?)


I've been wanting to make one of these, but the threads detailing all the frustration at getting them to run has made me wait until I get a little more experience.

Chris, you have to get your elbow running, to encourage me to dive in!

[raynerd]

rleete - afraid I can`t give you much encouragement as is still sat on the workbench awaiting review! That doesn`t mean I have given up, just had and have a few more projects that I would like to complete first. I have a skeleton for this engine and it is a case of tweeking things and I also need a flywheel which I should have within a fortnight. Once I have a flywheel then I`ll take another look at it. Another problem is that I don`t have a blow lamp and so I need to take it to my brother-in-laws, only around the corner but it has stopped me moving on it yet....

Cedge - yep, very "simple" parts, a bugger to get running together. I think the bend in the pistons could be half the battle!