LTD Stirling

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hawkman

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Powder keg said:
...Can you glue stuff to Graphite?
Sounds kinda dicey to me. I would be afraid that even if it adhered to the surface it might flake off a thin surface layer when stressed. I have one with a 12" flywheel and there is quite a bit of "snap" when the piston reverses direction as it comes over TDC and BDC once it gets going good. I can hear the music wire connecting rod (which is preferably a little loose to minimize friction) click twice each cycle.

Senft uses a #4 machine screw with a nut on the top and bottom of the piston and a paper washer to seal it (and maybe cushion it a little so it doesn't crack). He files the sides flat on the top before drilling the hole for the connecting rod to pass through. Make sure all of this claptrap clears the bottom of the cylinder or passes through the air hole in the bottom without hitting.

I found that a #4 screw thread didn't totally clear the hole in my piston and the screw kinda tapped threads in the graphite as it went in. It held so good I never went back and put a nut on the bottom.

Anyway, the graphite material is very brittle and can crack easily if stressed.
 

Powder keg

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Thanks for the input Hawkman.

I carved out the bottom so the epoxy would "capture" the piston. I'll try and get a picture. I have more done. I drilled and tapped the holes for the screws that hold the piston and gland to the top plate. I drilled and tapped the holes that hold the flywheel onto the hub. I have a couple more things to do and then I can start assembly:eek:)

I hope it runs, Wes
 

Powder keg

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I have 2 more pieces to make, then I can start assembly. I need to do the seals for the displacer cylinder also. I'm looking at maybe this weekend for start up:O) i hope it runs.

Wes
 

Powder keg

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Got some more done. I read an article that talked about sealing the displacer cylinder. It said to use silicone to make the seal. To do this you simply put a bead of silicone on the edge of the cylinder and then lay it down on a sheet of waxed paper. I was skeptical because I thought silicone stuck to everything:eek:)

Well it worked great!!!


You can see the flashing still on the edges. This scrapes off easily with a sharp knife.

Later, Wes
 

Powder keg

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It Runs!!!!! :eek:) :eek:)

There are a few problems that I could have avoided If i wasn't so impatient. There are a couple of air leaks that you can hear in the video. I had to make the holes for the pins that holds everything together bigger so the displacer cylinder didn't rub. But it runs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :eek:)

[ame]http://www.youtube.com/watch?v=pvVD_czX_I8[/ame]

I'll get all this fixed and post a longer video. I think to be really LTD it will need bearings. But it will run on hot water. I ran it for 3-4 min before it stopped. I had put Ice on top and the water that melted off got sucked into the cylinder and the condensation made it quit. But It Runs:eek:)

Later, Wes
 

Powder keg

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Thanks:eek:) I'm just glad it ran. I am in the process of fixing the air leaks. I'm doing the thing with the silicon to the brass pieces on top. I'll try and get it back together tomorrow. I can't believe how quiet it is. Almost like it shouldn't be running.

Later, Wes
 
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Bogstandard

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Well done Wes, I've got the starting phase to go thru on mine in a few days, just hope they run as well.

John
 

Powder keg

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Got it back togather. Won't run at all now. I'm about ready to flip it into the trash. I'll fit some bearings and see what happens.

Wes
 

rake60

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You did get it to run Wes.

You're way ahead of me! ;)

Rick
 

Brass_Machine

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Powder keg said:
Got it back togather. Won't run at all now. I'm about ready to flip it into the trash. I'll fit some bearings and see what happens.

Wes
Don't give up on it yet. It ran once... it will run again. Take your time and go through it all. You will get it.

Eric
 
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Bogstandard

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Come on Wes,

Don't give up that easy, it is most probably a simple little setting that is stopping it.

John
 

Powder keg

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I'll get it:eek:) I some times get frustrated after a long work day. (Note to self, Don't work on little engines after a bad day of work:eek:) I'll see what happens when I fit the bearings. Also I still have a small leak somewhere?

Thanks, Wes
 

chuck foster

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don't give up wes.............it ran once it will run again......like john said it is likely just an adjustment.
i built a little gas engine last year, first flip and away it went. it ran for about 3 hours non stop, so i took it apart and painted it. i was very carefull not to get paint were it shouldn't be . i put it all back together and it wouldn't run at all, after 3 or 4 days of trying to get it running (and it wouldn't) i almost threw it against the brick wall :mad:
if i was 18 again that engine would have been beat to death with a hammer, but now that I'm older i just put it in a box and forgot about it.
2 or 3 weeks went by and my dad asked about the engine, i told him all about it and it's problems. he just laugh at me and said i didn't know what i was doing (he is abit of a smart so and so :D) with that i gave him the engine and told him i never wanted to see it again, well the smart so and so brought it back the following weekend and ran it for me!!!
he never has told me what was wrong with it, but i did have the last laugh because he was running it for some friends (showing off) and it fell off the work bench and the one flywheel broke and the crankshaft bent real good :D

now that i have babbled on my point is if you get flustered put it aside and forget about...........and if an old smart so and so offers to fix it..............let me know and i will come pick him up cause my mom let him escape ;) :eek: (dad if you ever read this.....love ya dearly)

chuck
 

Powder keg

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I went through my stuff and found some shielded bearings that I think will work. I'll try and degrease them. I also started disassembly and there is still a leak somewhere? With the con rod off the piston will drop to the bottom. and the displacer rod wont move freely any more? I can lift it up and it stays there? Maybe I got some silicone where It didn't belong? We'll get these fixed and see where it stands:eek:)

Thanks for the moral support:eek:), Wes
 

Davyboy

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Hi Wes, that's one beautiful engine. I love the way you made both pistons visible, it's cool watching them run at 90 degree phase to each other. I know you'll get it running again soon, you could probably use a good nite's sleep! ;D Hang in there.
Davyboy
 

Powder keg

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Not really, I've been busier that a one legged man winning a but kicking contest:eek:)

Should be back to it next week? Wes
 

steamer

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Hi Wes,

I built Rudy's "Little Work Horse" engine twice scale, and following Rudy's advice I was very carefull with dimensions (so I thougt). When time came to start she would not go...fought it for three hours! :mad:.....it almost went into orbit, but I took a deep breath and ditched all assumptions and started measuring. After another couple of hours, I found the threaded hole in the slide valve nut was tapped slightly out of square. I fit the nut to the valve so close that it was holding the slide valve off it's seat!....couldn't have been more than a few thou but it was enough!
A couple of strokes of the file to thin the nut up a bit..and it "runs like a hose" ;D

Hang in there Wes....double check the assumptions....you'll find it!


Dave

 
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