Sterling(beta) refuses to work at all after 7 builds.. Help!

Discussion on Stirling or "hot air" engines (all types)
Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Sat Mar 02, 2013 9:23 pm

Insainhouserecords wrote:Thank for the info, I was thinking maybe my displacer had too much loose room and was letting the air pass by without this cycle taking effect. I was thinking piston but I guess that why its called a displacer. I was going to even try a solid arm displacer but its more complex for sure. So, Are you saying that even with the "pipe on side" unit it should still work the same way? My PVC opening is 3/4in and when I apply heat on the bottom it does swell but when the displacer and everything is intact it only swells when I turn it over but the "swell" isn't as great of a "swell".
Yes it should work the same way.

What plans are you using as your basis? Is it the scrap to power easy can engine?
But it looked in your pics like you were using two larger steel cans instead of aluminum beer cans?
If so, you can scale up the area of the end of the can from beer can to bean can, then scale up the area of the diaphragm by a similar amount, and the strokes by similar amount. Plenty of online calculators to calculate area of a circle and ratios of size etc.

But even then the original design used aluminium cans not steel. The thermal properties of the metal can make a big difference to things.
That is why it is best to take an established design and follow it exactly first time round.

Hopper
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Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Sat Mar 02, 2013 9:37 pm

Heres a video that explains how the displacer works better than I can explain it.

In your case the power cylinder is directly connected to the can with no small tube but it all works the same.

Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Sat Mar 02, 2013 9:37 pm

Hmm, I didn't know it was actually that finicky. I figured the measurements would be slightly different. So, basically I just took two tin cans and attached a 90' PVC almost at the very top of one. Then I made my displacer 2 1/2 inches thick because the inside of the can to the top of the PVC pipe is 4in. This leaves me with 1 1/2in for crank throw and top and bottom air space. I then made my displacer crank at 1/2in. This makes 1 whole turn a full inch of movment for the displacer and leaves me with 1/4in space top and bottom. Does any of this sound accurately made? Oh, yes this is based on the "simple can engine"

Hopper
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Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Sat Mar 02, 2013 9:47 pm

Insainhouserecords wrote:Hmm, I didn't know it was actually that finicky. I figured the measurements would be slightly different. So, basically I just took two tin cans and attached a 90' PVC almost at the very top of one. Then I made my displacer 2 1/2 inches thick because the inside of the can to the top of the PVC pipe is 4in. This leaves me with 1 1/2in for crank throw and top and bottom air space. I then made my displacer crank at 1/2in. This makes 1 whole turn a full inch of movment for the displacer and leaves me with 1/4in space top and bottom. Does any of this sound accurately made? Oh, yes this is based on the "simple can engine"
If your can is 4" tall and your displacer is 2.5" and total displacer stroke is 1", that leaves about 1/4" air space at each end, which is maybe about right. (And that is to the very end of the can, not to where the plastic pipe connects.)

But yes, the measurements are quite finicky, very finicky in fact. So if you are not using the original size cans, you will have to work out the relevant scaling to make the stroke and diaphram sizes match the larger cans.

It would be just as easy to go back and remake the engine exactly to the original plans and then it should work.

Insainhouserecords
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Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Sat Mar 02, 2013 9:59 pm

Correct, I guess Im just stubborn. I know his model works, most of the thrill for me is making my own work honestly. If I really wanted one right now, I could probably just make the ez sweet tin stirling.

Insainhouserecords
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Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Sun Mar 03, 2013 5:13 pm

I know your tired of hearing it, but could the diaphragm be too small if its swelling just not quite enuf to push the rod on over.the balloon only has extra "pulling" tension against the crank when its not being heated. Also, I know you need a counter weight but does it need to be placed to counter the tension of the balloon or to counter the larger displacer crank slot? My crank turns smooth but at a point here and a point there the crank will tend to want to settle at a perticular place rather than just spinning unit it's energy is spent. This is a problem right?

Insainhouserecords
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Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Sun Mar 03, 2013 5:50 pm

I got it!! It works! Omg! I was like, damn. I must have spun it hard... Wait.. Wait.. Oh god! Get me that camera! It works!!!

Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Mon Mar 04, 2013 2:54 am

Insainhouserecords wrote:I got it!! It works! Omg! I was like, damn. I must have spun it hard... Wait.. Wait.. Oh god! Get me that camera! It works!!!
Cool! Congratulations!!! You did it!!!!!
Got video of the beast in action?

Have fun.

Insainhouserecords
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Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Mon Mar 04, 2013 7:46 am

Lol, yea all 50-65 rpms worth! It's not the best by any means but man I got to tell you, it has came along way! Thank you Hopper. I am using an iPhone to upload my video to YouTube but the thing is it keeps saying it could t be uploaded. When I try to upload the vid strait to here, my browser gets stuck. I'm going to figure it out and post the link.

Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Mon Mar 04, 2013 5:47 pm

Insainhouserecords wrote:Lol, yea all 50-65 rpms worth! It's not the best by any means but man I got to tell you, it has came along way! Thank you Hopper. I am using an iPhone to upload my video to YouTube but the thing is it keeps saying it could t be uploaded. When I try to upload the vid strait to here, my browser gets stuck. I'm going to figure it out and post the link.
Slow and steady wins the race.
Or put two candles under it instead of one and see if that speeds it up.

Have fun!

Ian S C
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Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Ian S C » Tue Mar 05, 2013 3:33 am

It will be something similar with vidios, with photos I reduce the size to 640 x 480, i'v never down loaded a vidio.
CONGRATULATIONS, even the best of machined motors can take a bit of time and effort to get going, and sometimes I'v just about given up, But the more you build the easier it gets. Ian S C

Hopper
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Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Sun Mar 17, 2013 7:54 pm

Well, after following this thread for a while I had to have a go at one of these tin can engines myself. I have made engines on my lathe before but never out of old tins and nails and bits of wire.
I had an old sweets tin lying around so I made an engine to Myfordboy's EZ Stirling design and it works a treat, running for hours on a tiny little tea candle for power.

Couple of things I learned along the way:
WD40 sprayed on the latex diaphragm makes it much more flexible and so it absorbs less power to stretch it to top and bottom dead centre. Pretty much a must do to get mine running.
Then check that the power connecting rod is EXACTLY the right length. Do this by disconnecting the con rod at the crank shaft then move the displacer up and down manually. Observe that the con-rod end moves up and down an even distance above and below the centre crankshaft. If the rod is too short, it will go down further from the centre point than it goes up, so I had to uncurl a little of the wire wrapping around the crankpin to make the rod that 1 or 2 mm longer.

Then away she went.

Image

And I found that gluing a small coin to the flywheel to balance the displacer piston with the power connecting rod uncoupled helped squeeze a few extra rpm out of it.

Another thing I learned was that tea candles put a thick layer of carbon on the bottom of the tin, and if you get it on your hands and then leave indelible black marks on the dining table, 'er indoors is very much not impressed.

Next project is a half-scale version made from a single-serve catfood tin -- with a clean spririt burner for power.

I'm hooked.
Last edited by Hopper on Sun Mar 17, 2013 8:01 pm, edited 1 time in total.

Insainhouserecords
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Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Sun Mar 17, 2013 8:00 pm

That's awesome! It looks great! You should think of you tubing a vid of it running, it looks fast.

Hopper
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Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Sun Mar 17, 2013 9:19 pm

Insainhouserecords wrote:That's awesome! It looks great! You should think of you tubing a vid of it running, it looks fast.
All I got to do is remember how to use my camera to take video. Doh!

Opulents
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Location: Brunswick georgia

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Opulents » Tue May 14, 2013 9:57 am

I'm new and this has been an interesting lesson on what not to do. I wish you luck

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