LTD Stirling

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Brass_Machine

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Check your lens, make sure it is clean. Even the smallest smudge with make the autofocus screw up. Make sure sure you are in macro mode.

Eric
 

Powder keg

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Got a little more done today. I made the graphite bearing, the crankshaft, and what will be the balancing discs. It spins pretty good I think.


It's starting to look like an engine now:O) I hope it runs.

Wes
 

cfellows

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That's looking great, Wes. That's going to be one nice engine when it's finished...

Chuck
 

Powder keg

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Here is the power cylinder assembly. This is an Airpot cylinder. I will epoxy it to the brass base. I still have to drill and tap the brass so I can mount it to the top plate. I am going to change my plans to make the Airpot piston work.


Getting closer:O) I hope it runs.

Wes
 

Powder keg

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Well, I have the foam ready to work. It is 9/16" thick and a little bigger than the cylinder. I still cant figure out a good way to hold this with out smashing the crap out of it or ruining it when I remove it (tape) ? Any Ideas? I've got plenty of extra to "practice" on:O)

Thanks, Wes
 
J

jpowersny2

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How about sandwiching it between two pieces of something: plywood, plastic, etc? You could make the top and bottom plates a little smaller so they don't need to be turned down, and then just use sand paper so that only light pressure is needed, and hence not much torque.
 

Powder keg

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That will work for the OD. But what about the top and bottom? I'd like them to look nice. I think if I taped them, Id have trouble getting it off with out dinging the foam up bad?

Wes
 

hitnmiss

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I tried hot wire cutting mine with less than great results.

I ended up taping my foam and flycutting 1/2 off each side (to control warp). I used alcohol to dissolve the glue on the tape, worked like a champ.

I tried acetone 1st, that succeeded in melting my foam displacer!
 

Powder keg

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Well I made some more progress today. I decided to machine the outside of the displacer's with my dremel tool. Worked good to:O)

[ame]http://www.youtube.com/watch?v=WWMs4UXN9Hs[/ame]

I'll cut the pistons to length with my bandsaw and sand them to clean up the ends. Then I'll lightly chuck them up to drill the center hole.

Wes
 

rake60

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Nicely done!

I'd call that a live spindle on a manual machine.
Those industrial CNC's will plant new ideas every day! ;)

Rick
 

Powder keg

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I had thought about that, But my big lathe is tied up and my smaller lathe is to small. That is a very good idea though.

Thanks, Wes
 

Powder keg

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I finished the displacer piston's and the rod that gets epoxied into it today. I'll get a picture when I epoxy them together tomorrow. I also started on the piece that will get epoxied into the piston and hold the con rod. I'm going to use silicon to for the gasket on the displacer cylinder. I'll show that to.

I hope it runs, Wes
 
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hawkman

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I have had good luck using a 3-M ROLOC disc and arbor in a drill press. As you are taking it down to final thickness, keep flipping it over and it will turn out very flat with uniform thickness. There is also a low risk of catastrophic failure (flying across the room like a frisbee) if you hold it flat against the drill press table at all times.


displacer_1.jpg
 

Powder keg

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Well, I've got more done. Having more puter problems. I cant fix my pictures:O( I have the rod for the displacer done and the gland almost done. I just have to finish a couple more parts, Glue a couple of parts together, and start assembly:O)

Hawkman, What plans are you using?

I hope it runs, Wes
 
H

hawkman

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I haven't followed any plans exactly, but have followed the principles and rough dimensions of Dr. James Senft's N-92 and P-19 engine designs (but then all LTD heat engines are derivative of his design).
 

Powder keg

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Thanks, I'll have to get that book:O)

Here is a quick picture. Kinda bad quality, but you'll get the idea.


When I drilled the foam, something wasn't aligned right. The hole is about .025 over sized. I'll probably go ahead and use them as is. To glue them up I'll chuck the rod in my drill press chuck to hold it upright until the epoxy dries. The aluminum shaft will get glued into the piston. There is a small hole in the end for the con rod.
 

Powder keg

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Good question? I'll get back with you on that :O) LOL

Wes
 
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hawkman

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If you have clearance on the bottom of the piston, you could probably put a blob of epoxy on the underside in contact with the shaft poking through the hole to captively "pin it" in.
 

Powder keg

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Thanks! That will work great. Still, Can you glue stuff to Graphite? I'll have to try a couple of things:O)

Wes
 
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