Author Topic: Uncle Tom's Coffee Cup Engine  (Read 3019 times)

Offline stevehuckss396

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Uncle Tom's Coffee Cup Engine
« on: November 16, 2013, 11:32:12 PM »
As a project with the metal club I am going to build this engine. I was wondering if anyone has built it and if it ran well when complete.

http://www.tomsinstitute.com/html/coffee_cup_engine.html

Knowing absolutely nothing of this type of engine there are a few questions I would like to ask.

Is the thickness of the 2 aluminum plates important to the way it will run? I am going to look for the plate aluminum .036 thick. Weird number and 1/32 is .031 and may be easier to find.

Also there is a diaphragm .006 thick latex. What would that be exactly. Could I use a piece of balloon or something else?

I was also considering replacing the CD flywheel with an aluminum flywheel with some custom work. Would the heavier flywheel hurt or help?

No clue here folks, any help would be great.

Also if there is another option that would run better let me know.

Thanks!!
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline mklotz

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Re: Uncle Tom's Coffee Cup Engine
« Reply #1 on: November 16, 2013, 11:45:22 PM »
1/32" aluminum should be just fine.

For the diaphragm, think birth control.  Most of these engines have a real cylinder with a graphite piston.  I think the diaphragm design is suspect and has a real potential for construction difficulties.

I would stick with the CD flywheel.  These engines don't have enough power to get out of their own way.  Do some decorative carving of the disk if you can't contain your desire to bling.

I built Jerry Howell's "Miser",

http://www.jerry-howell.com/Miser.html

in half scale and it runs very nicely on my coffee cup or a saucer of ice cubes. 
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fcheslop

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Re: Uncle Tom's Coffee Cup Engine
« Reply #2 on: November 17, 2013, 12:22:11 AM »
Ive used surgical gloves for the diaphragms and they seem to work OK and 1mm alloy again no problems
cheers

Offline stevehuckss396

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Re: Uncle Tom's Coffee Cup Engine
« Reply #3 on: November 17, 2013, 12:29:12 AM »
1/32" aluminum should be just fine.

For the diaphragm, think birth control.


I was thinking the same thing. Hilarious.

Half scale Jerry Howell. I will look into that. I like the idea of building smaller as long as it still runs.

Thanks Marv
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline b.lindsey

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Re: Uncle Tom's Coffee Cup Engine
« Reply #4 on: November 17, 2013, 01:37:23 AM »
Steve, like Marv, I also built Jerry Howell's half scale Miser and it's still one of my favorites. As you will see, it is a more substantial engine but also more machine work compared to the one you are showing. It does have the benefit if using an aluminun flywheel which with your CNC skills could be done in a nice curved spoke version. It does require bearings though which can probably still be ordered through Jerry's site, or via places like Boca Bearings, etc. Really will depend on how much machine work you want to put into an LTD Stirling, but they are fascinating little engines.

Bill

Offline sbwhart

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Re: Uncle Tom's Coffee Cup Engine
« Reply #5 on: November 17, 2013, 06:39:39 AM »
I've just built a similar engine loosely using the plans on John Tom, they are a bit temperamental to say the least, they have to run perfectly free no tight spots, I made mine with a CD fly wheel, a brass cylinder and a ally piston, I would like to use a glass cylinder and a graphite piston but I can't find a supply of glass tube with an accurate bore(no ovality and parallel). Making the displacer piston was a bit of a challenge I used polystyrene loft insulation I turned it up by making a wooden face place and sticking the piston to it with two way tape.

I used 3/8" thick ally for the top, cold plate: and 1/8" copper thinned down in the middle to 1/6" for the bottom, hot plate, these have to be sealed to the displacer cylinder I used gasket card held in place with Hematite blue.


<iframe width="560" height="315" src="//www.youtube.com/embed/VOWRpk_17TA" frameborder="0" allowfullscreen></iframe>

It will run for about 20min on one cup of tea,:- milk no sugar  :Jester:

Stew
« Last Edit: November 17, 2013, 06:43:24 AM by sbwhart »
A little bit of clearance never got in the way

Offline mklotz

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Re: Uncle Tom's Coffee Cup Engine
« Reply #6 on: November 17, 2013, 03:53:36 PM »
Quote
these have to be sealed to the displacer cylinder I used gasket card held in place with Hematite blue.

Remember these are extremely low pressure engines.  I "sealed" my plates to the perspex displacer chamber with a thin coat of Vaseline.  The engine is many years old and still performs perfectly.
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Offline sbwhart

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Re: Uncle Tom's Coffee Cup Engine
« Reply #7 on: November 18, 2013, 07:33:39 AM »
Hi Marv

I did toy with the idea of using that method but I have a tendency to over engineer/complicate things, its just my way, but it good to know that it works next time I strip it down to tinker I'll use that method.

Cheers

Stew
A little bit of clearance never got in the way

Offline Ian S C

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Re: Uncle Tom's Coffee Cup Engine
« Reply #8 on: November 18, 2013, 11:17:20 AM »
Stew, I don't know what the story is in UK, but those who are in the USA can send an E-mail to the Airpot coy. and get a free sample of glass cylinder, and graphite piston.
         My LTD motor has the top and bottom made from the base of two aluminium fry pans, the  Larger of the two I cut a ring from, that forms the rim of the fly wheel, this is attached to the hub with six spokes made from bike spokes. The cast iron power piston runs in a cast iron cylinder.   Must get it going again.     Ian S C

fcheslop

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Re: Uncle Tom's Coffee Cup Engine
« Reply #9 on: November 18, 2013, 04:52:14 PM »
For decent glass tubing in the UK try Pyrex it tends to vary slightly in dia from tube to tube but is true and round or at least good enough for a Laminar style engine.
cheers