# LTD Stirling



## Powder keg (Jan 21, 2008)

Well I couldn't wait till I had a weekend. I started school again and I have the opportunity to practice my CNC skills:O) So I started on my engine. I did the displacer cylinder a few days ago. It was turned in my lathe using a 3 jaw. I'll recreate that and post some pictures. Today after work I set the mill up and machined the pedestal. The main shank on it will be turned round in my lathe. I left a nub so I could center the piece in my lathe. After it is done, this will be removed. I didn't get any pictures because you couldn't see anything under the flood coolant. 







Hope it runs:O)

Wes


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## Powder keg (Jan 23, 2008)

I used the acrylic containers from Walmart to make the displacer cylinder. To make them, I cut them using my band saw. I set the fence and slowly cut the pieces off. Here are a few practice pieces. 




Next, I chucked them up in my 3 jaw on my lathe and slowly trimmed them to length. I was only taking .010" cuts here. I was worried that It would come flying out and break. Didn't happen : O)





Today I had a chance to run the CNC after work and made a couple Flywheels. They took 10 minutes to machine. I still have to deburr these. They are 5" in diameter and .085" thick. They are fairly close to the size of a CD.





I'll make some more stuff later this week. 

I hope it runs:O)

Wes


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## Brass_Machine (Jan 23, 2008)

Right on Wes!

Those flywheels look good.

Eric


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## Powder keg (Jan 24, 2008)

Messed around with another Flywheel design. I think I like the curved spoke model. 





Wes


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## Powder keg (Jan 25, 2008)

Made a little progress:O) I made a jig to hold the flywheel pedestal while i turn it in the lathe. I had a picture of me center drilling the end in the mill, but it was to fuzzy?





I chucked the piece up in the lathe and put a live center in the end to support it. 





Here is an action shot:O) I'm turning the pedestal round. 





To clear the 4-40 screws, I had to reposition my tool. 





To be continued.......


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## deere_x475guy (Jan 25, 2008)

Wes, looks like things are coming along nicely. Looks good and I like the way you showed how your fixture was used. Very nice!


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## Powder keg (Jan 25, 2008)

Thanks! I forgot to mention an important part. There is a key way cut in the end of the fixture that locates my piece. It also takes the strain off of the screws so they don't snap off. 

Later, Wes


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## Brass_Machine (Jan 25, 2008)

Very cool Wes!


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## Powder keg (Jan 26, 2008)

A couple of these brass pieces warped when I turned them round. To true them up again, I chucked on the round part and faced the end off. I'll post a picture later:O)

Wes


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## Powder keg (Jan 27, 2008)

The way I did these brass pieces would make nice looking Con Rods on a little bit bigger engine. 

Just a thought, Wes


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## Powder keg (Jan 27, 2008)

The fuel of tomorrow:O)

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

Wes


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## Powder keg (Jan 28, 2008)

I am planing on machining the top and bottom plates for my engine during school. I'll try and get a good video. It should be pretty neat. My engine is going a lot faster because of these CNC machines. I have the hardest pieces built now. The rest will mainly be lathe work. 

I think I would have had a hard time building this in a weekend. There is two much "figuring out stuff" involved. I still have to mess with the displacer cylinder. I bought the foam today. Ended up with some Blue stuff. The 1" was cheaper than the 3/4" so I'll have to bandsaw it down a bit. I'm still not sure how I'm going to machine the foa in my lathe? But I'll get it:O)

Wes


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## kustomkb (Jan 29, 2008)

Nice progress and good job with the step by step pics, I need to do that more.
When I built my LTD I made an Al disk which was a light press fit into the disp. cyl. so I could securely chuck
the OD and the acrylic wouldn't warp in order to get a flat face. And in case it grabbed when doing the o-ring
grooves. For the disp. I clamped it to the table under another Al disk and ramped down the outside on the cnc mill. Gave a real nice finish. I think we are the same age, been at this the same amount of time and have built
several of the same engines. What a crazy world!

Keep the pics coming

cheers,

-Kevin


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## Powder keg (Jan 30, 2008)

Well I feel kinda bad. There's been bad snowy weather here and I was thinking of the drive to school about 50 miles away, and i forgot my camera:O( I wasn't able to get a video. The top and bottom plates are machined. It took about 4 min. to drill and machine each piece:O) I had the spindle set at 4000 RPM's :O) I'll post pictures after work tomorrow. 

Later, Wes


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## Powder keg (Feb 2, 2008)

Thursday I called to see if class was still a go and the instructor said it was. So, I braved the snow and made it to class. I was the only one who shower up:O) I must be dedicated:O) Anyway we tried to make another part for my LTD. The two bolts that hold everything together are pretty small. We didnt know if we could make them or not on the CNC lathe. They were to small to thread there, But I was able to blank them out. Here is what I ended up with. I still have to Debur them. 





The bottom plate needed a counter bore because I wanted the bolt heads to be flush. I ground a 1/4" drill bit down on a surface grinder. It worked really good. 





Wes


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## Powder keg (Feb 2, 2008)

I forgot this picture. 




This is the bottom of the flywheel pedestal. I mentioned earlier that the pedestal's warped when I machined them round. I chucked them up in the middle and took a skim cut off the bottom. This evened everything out nicely. 

Wes


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## Powder keg (Feb 2, 2008)

I finished some of the bolts that hold the two half's and the flywheel pedestal together. I used a little split bushing to hold them while i threaded them. It worked pretty good. 





Later, Wes


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## Powder keg (Feb 3, 2008)

Got the bearing boss made. It is a snug fit in the flywheel pedestal. I'll solder them together. 





I'm going to try and get the bearing made so I can mount the flywheel:O) today.

I think my camera is on it's way out? I'm having trouble getting it to focus up close?

Wes


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## Brass_Machine (Feb 3, 2008)

Powder keg  said:
			
		

> I think my camera is on it's way out? I'm having trouble getting it to focus up close?
> 
> Wes



Have you been able to take close ups before (that close any way)? My digital has a 'macro' button for close up photography (macro).

Eric


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## Powder keg (Feb 3, 2008)

Yea, I've been able to take pictures 1" away with crystal clear pictures in "macro" before?

Wes


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## Brass_Machine (Feb 3, 2008)

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


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## Powder keg (Feb 3, 2008)

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


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## cfellows (Feb 3, 2008)

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

Chuck


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## Powder keg (Feb 4, 2008)

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


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## Powder keg (Feb 4, 2008)

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


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## jpowersny2 (Feb 4, 2008)

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.


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## Powder keg (Feb 4, 2008)

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


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## hitnmiss (Feb 5, 2008)

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!


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## Powder keg (Feb 6, 2008)

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


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## rake60 (Feb 6, 2008)

Nicely done!

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

Rick


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## Powder keg (Feb 8, 2008)

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


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## Powder keg (Feb 9, 2008)

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 (Feb 10, 2008)

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.


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## Powder keg (Feb 11, 2008)

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


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## hawkman (Feb 11, 2008)

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).


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## Powder keg (Feb 11, 2008)

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.


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## hawkman (Feb 11, 2008)

Are you sure glue will stick to the graphite?


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## Powder keg (Feb 11, 2008)

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

Wes


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## hawkman (Feb 11, 2008)

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.


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## Powder keg (Feb 11, 2008)

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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## hawkman (Feb 12, 2008)

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.


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## Powder keg (Feb 18, 2008)

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)

I hope it runs, Wes


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## Powder keg (Feb 22, 2008)

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


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## Powder keg (Feb 24, 2008)

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) 

Well it worked great!!!






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

Later, Wes


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## Powder keg (Feb 24, 2008)

It Runs!!!!! ) )

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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! )

[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)

Later, Wes


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## shred (Feb 24, 2008)

awesome.. great work!


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## Brass_Machine (Feb 24, 2008)

Way cool Wes! Nice job


Eric


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## Powder keg (Feb 25, 2008)

Thanks) 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 (Feb 25, 2008)

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


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## Powder keg (Feb 26, 2008)

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


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## rake60 (Feb 26, 2008)

You did get it to run Wes.

You're way ahead of me!  

Rick


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## Brass_Machine (Feb 26, 2008)

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 (Feb 26, 2008)

Come on Wes,

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

John


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## Powder keg (Feb 26, 2008)

I'll get it) 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) I'll see what happens when I fit the bearings. Also I still have a small leak somewhere?

Thanks, Wes


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## chuck foster (Feb 26, 2008)

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 
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 ) 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 

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   (dad if you ever read this.....love ya dearly)

chuck


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## Powder keg (Feb 27, 2008)

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)

Thanks for the moral support), Wes


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## Davyboy (Feb 28, 2008)

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


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## Brass_Machine (Mar 5, 2008)

Any update Wes?


Eric


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## Powder keg (Mar 5, 2008)

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

Should be back to it next week? Wes


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## steamer (Mar 8, 2008)

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! .....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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## Brass_Machine (Mar 27, 2008)

Hey Wes... any news on this??

Eric


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## Divided He ad (Mar 28, 2008)

Hi Wes, looks good, hope you found the gremlin and kicked it's ass!? ;D

love the flywheels.... wish I had access and could use for that matter a cnc setup.
Would sure help with the precision issues I have! 

Ralph.


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