My First Walking Beam Stirling engine build with pictures

Discussion on Stirling or "hot air" engines (all types)
manvstaco
Posts: 15
Joined: Wed Sep 02, 2015 9:17 pm

My First Walking Beam Stirling engine build with pictures

Post by manvstaco » Thu Sep 03, 2015 11:33 pm

From start to finish.. (build currently still in progress)

Casting the Flywheel
Aluminum ingots made from soda cans
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Flywheel made from foam
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inside forge after the pour
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first was a failure, got a bit intimidated with a foot and a half of flames shooting out towards my face while pouring molten aluminum so I hesitated, causing this mistake. Live and learn...
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Second casting was a success!
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Turning the flywheel on my 12x22 inch grizzly metal lathe, the overall outside diameter is six inches
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Flywheel supports

I decided it would be fun to use my homemade CNC router to make these. I designed them with Google sketchUp
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With bearings
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More support
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Staging Middle Support for Rocker arms

These parts were also cut using my homemade CNC, These will not be the cylinders I will be using, they are being used for placement and planning
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another
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Building the Main Cylinders

Hightemp JBweld used to joint 1 inch copper pipe to Large spray paint can
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with brass piston
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Water jacket and bottom heat shield installed. Hightemp fireplace adhesive rated at 2000 deg F was used as well as high temp JB weld on the cold side
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Started painting a bit
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More paint! High temp rated at 1200 deg F. Honed out the cylinder wall with a brake hone, as well as steel wool wrapped around a drill bit to polish it up for 10 minutes
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New Chimney!
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Displacer Piston

2.5 inch diameter, 2.5 inch stroke in the large spray paint can
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Power Piston

Brass 3/4 endcap was spun down and coated with a 2 part epoxy/graphite mixture and let to set overnight, spinning it on the lathe
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Linkage connected to power piston. It takes over 20 seconds for this piston to travel 3 inches when making it airtight and letting gravity pull the cylinder downward inside of the copper tubing. It's almost impossible to make a copper pipe from the hardware store completely round without a boring bar(which I don't currently have) that I'm aware of, it's not perfect but it will do for now. Thinking replaceable piston wall inserts for the near future.
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High temp silver solder
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Pressure chamber top, aluminum can was used as it fits perfectly over the top of my paint cans used. High temp JBweld was used to fix the brass tubing to the aluminum.
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I did the first bore stroke test tonight, I heated one side of the engine and move the displacer piston giving my power piston 3 inches of travel. Now I know the cam should be offset by 1.5 inches.
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Cam
1.5inch offset from center.
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Brass bushing was used to reduce friction
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another
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Possible piston sleeves
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9/7/2015 half way there!


9/13/2015 Engine tweaks!


9/17/2015 More photo's added above!

More to come, I'll post as I build!
Last edited by manvstaco on Thu Sep 17, 2015 5:45 pm, edited 4 times in total.

Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: My First Walking Beam Stirling engine build with pictures

Post by Ian S C » Fri Sep 04, 2015 4:38 am

Hi, Welcome to the forum. Looks like your really getting into it. Brass tube would be better than copper for a cylinder, and a steel piston, nicely polished would be a good choice. Better still would be a steel cylinder, with a cast iron piston.
I would say that with the work I'v seen so far, you could make your own boring bar. An old high tensile bolt would do for the bar, and if you have a broken tap, or centre drill, drill a cross hole in the bar to take the bit of HSS, drill another hole, and tap it for a grub screw to hold the HSS tip, arrange some way of holding it in the tool post, and there you done it your self. Ian S C

manvstaco
Posts: 15
Joined: Wed Sep 02, 2015 9:17 pm

Re: My First Walking Beam Stirling engine build with pictures

Post by manvstaco » Fri Sep 04, 2015 7:24 am

Thank you for the feed back Ian S C, That's a good idea, I would like to do something different with my power piston and add a cylinder sleeve. I'm thinking I can use the existing copper tube as a place holder for a replaceable piston sleeve. I'll give the welding shop a call today and see if they have any brass tubing.
Last edited by manvstaco on Fri Sep 04, 2015 4:28 pm, edited 2 times in total.

manvstaco
Posts: 15
Joined: Wed Sep 02, 2015 9:17 pm

Re: My First Walking Beam Stirling engine build with pictures

Post by manvstaco » Fri Sep 04, 2015 4:26 pm

Looks like no one sells brass in Kitsap county, I'm stuck with what I can buy at the hardware store plumbing section or online. Do you feel like your suggestion (brass piston and cast iron cylinder wall) is comparable to a graphite piston with a glass cylinder wall? Would I lube it with a light oil? I priced out actuators from airpot.com which were around 15 bucks a piece but because I don't have a business license or a large order I was told to contact a local vendor in Oregon that quoted me 89 bucks a piece! Wow what a mark up. Thinking about making my own from glass tubing and graphite rods from ebay.
Last edited by manvstaco on Sat Sep 05, 2015 10:40 am, edited 1 time in total.

burnit0017
Posts: 76
Joined: Sat Jun 26, 2010 9:54 am

Re: My First Walking Beam Stirling engine build with pictures

Post by burnit0017 » Fri Sep 04, 2015 5:40 pm

Hi, thanks for posting your project, I look forward toward your results.

Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: My First Walking Beam Stirling engine build with pictures

Post by Ian S C » Sat Sep 05, 2015 4:50 am

A good place to find steel tube ready to use, a car wreckers yard, shock absorbers, its a bit messy, but you have to open the unit, and inside there is a cylinder a foot or so long, about 1.250" to 1.5" maybe more or less bore tube with a polished bore. If you can, use little or no oil, and definitely NO oil on graphite pistons.
Ian S C

manvstaco
Posts: 15
Joined: Wed Sep 02, 2015 9:17 pm

Re: My First Walking Beam Stirling engine build with pictures

Post by manvstaco » Sat Sep 05, 2015 10:31 am

great idea on the shock absorbers! Mine are about due for replacements on my 2002 gti. As long as I don't have a core charge I'll hold on to em :)

Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: My First Walking Beam Stirling engine build with pictures

Post by Ian S C » Sun Sep 06, 2015 4:21 am

To open them, I use a hacksaw, at the ram end, about 1/2" back/just behind the seal cut until oil starts to seep out, carefully open it a bit and drain the oil, after that continue the cut right around without .nicking the ram.
Ian S C

manvstaco
Posts: 15
Joined: Wed Sep 02, 2015 9:17 pm

Re: My First Walking Beam Stirling engine build with pictures

Post by manvstaco » Mon Sep 07, 2015 9:28 pm

thanks for the tips Ian SC!

Here is today's progress, half way there! Hope you guys like :)


tew
Posts: 17
Joined: Thu Mar 05, 2015 11:06 am
Location: missouri,usa

Re: My First Walking Beam Stirling engine build with pictures

Post by tew » Mon Sep 07, 2015 10:04 pm

Very impressive.

Triangle.Stirling
Posts: 133
Joined: Mon Sep 09, 2013 8:29 am

Re: My First Walking Beam Stirling engine build with pictures

Post by Triangle.Stirling » Thu Sep 10, 2015 7:09 am

Hi,

Nice engine! It really looks nice, and runs nice.
As mentioned on Youtube, there is a 'knock' when running. Isn't your displacer knocking the bottom of the cylinder?

Really nice flywheel! I noticed you have a small (charcoal fired?) furnace.
Also interested how you make that neat styrofoam shape? But I guess that was done with your cnc? The casting turned out nice!

Good luck with the second cylinder, hope to see more of it!

manvstaco
Posts: 15
Joined: Wed Sep 02, 2015 9:17 pm

Re: My First Walking Beam Stirling engine build with pictures

Post by manvstaco » Thu Sep 10, 2015 4:11 pm

Thanks for the compliment Triangle.Stirling! Yes that is a small slightly beefed up version of the charcoal DIY forge I built following a tutorial from the"King of Random" on YouTube, but mine uses propane :D

The knock in my engine, I like it :) Your right! it's the displacer hitting the bottom of the cylinder.

Styrofoam shape, I should've used my CNC but did it by hand, one layer at a time 1/4" sheets from the dollar store with the paper peeled off of it.

manvstaco
Posts: 15
Joined: Wed Sep 02, 2015 9:17 pm

Re: My First Walking Beam Stirling engine build with pictures

Post by manvstaco » Sun Sep 13, 2015 10:34 pm

Here's an update on the progress I made over the week..

Shorted the stroke on the displacer piston (followed advise above)
Made new brass linkage, plumbing silver solder is working well!

Experimented with several different displacers, tried to see if oasis foam with 2 mm gap, oasis foam with steel wool wrapped around it, and the all steel wool displacer in the original build. The original out preformed the two other tests I did with the oasis foam, was a bit surprised as I though lowering the overall dead air volume would help.

Triangle.Stirling
Posts: 133
Joined: Mon Sep 09, 2013 8:29 am

Re: My First Walking Beam Stirling engine build with pictures

Post by Triangle.Stirling » Mon Sep 14, 2015 1:22 pm

Nice! I made that same forge, but it's almost falling apart. Bought an electric furnace that can go up to 1200 degrees C, hope to do some more casting in the future. That's really a nice flywheel considering the Styrofoam mold was made by hand!

Engine runs nice now, smooth.

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Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: My First Walking Beam Stirling engine build with pictures

Post by Ian S C » Tue Sep 15, 2015 2:14 am

Just been looking at your photos. If you find that the flanged main bearings tend to fall out, fit them on the inside of the uprights, with spacers between the bearings and the flywheel, these should just touch the inner race.
Ian S C

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