# Scratch-built Stirling



## ksouers (Jun 22, 2010)

Well, its been a couple months since completing the Elmers #6 so I guess its time for another project. I had been considering Elmers mine engine since before completing #6, but all the Stirling projects going on stirred up some old burning embers.

Ive been deeply interested in Stirlings since I first started reading about them in Popular Science and Popular Mechanics as a youngster in the early 70s. The Stirling was going to change the world, they said. We all know how that turned out; still, its a very interesting engine.

The magazine articles never went into the history of the engine, just talking up all the revolutionary research and development that was going on made it sound like it was some new engineering principle that had escaped from the darkest corners of Caltech or MIT. I was quite surprised years later to find out that it predates the Otto and Diesel cycle engines.

My first foray into the world of Stirling was about 20 years ago when I made a tin can model I had found plans for while surfing the pre-internet (library!). It was a wooden framed affair with a couple coffee cans for cylinders and soup cans for pistons with water to seal them. It was an Alpha type with one can being hot and the other cold, a fabricated copper pipe plumbed them together. I never did get it to work right; I think I got at most 2 revolutions before it would stop.

Now I venture into the world of Stirlings again, not armed with some plans from a faded magazine of days gone by. No, not this time. This time its scratch built. My own design. I dont have any plans or drawing made, just some numbers scratched out on a pad and the worst (incomplete) C-o-C youve ever seen. It makes a 7 year olds stick figure Hangmans drawing look like it was done by da Vinci. 

Its time to give credit where credit is due. There is nothing new under the Sun. Im relying on lots of people who have gone before me. In that vein Ive borrowed heavily from the designs of Terry Coss. His designs are straight forward and to the point yet quite elegant in motion and function in a modernistic style. Fear not, Cedge, your Victorian art is quite safe. 

Now, on with the show

I started with the hot cap using the classic rule of 3. The displacer cylinder is 3 times the diameter, the displacer piston length is 2/3 the length of the cylinder. The swept volume of the power cylinder is equal to the swept volume of the displacer, 1/3 the volume of the displacer cylinder. Everybody got that? Theres a test afterward.






The cylinder inside diameter is 1/2 inch, as thats the largest reamer I have. The hot cap is 12L14 steel, as thats what I had on hand, with a length (inside) of 3/4 inch, 1/2 the cylinder length. The cold side will also be 3/4 inch long. I have several of those aluminum blocks with the hole already drilled in them, now I know what to do with them. The hole is .400 inches, the block is about 1.5 inches on a side and 3 inches long, give or take.

It was a little warm in the shop so thats as far as I got.






Im not fond of sweat dripping off my nose and onto the machinery and glasses. The air conditioning wont arrive until October, so this is likely to be a very slow build.

Thanks for stopping in. I hope the next installment isnt too far away.


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## zeeprogrammer (Jun 22, 2010)

Excellent Kevin.

Can I take the test pass/fail? How about probation? Fail?

Looking forward to the build.


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## Deanofid (Jun 22, 2010)

Thanks for the invite to your new build, Kevin! It seems like certain engine types go in bunches. I guess it's 
the Rev. Stirling's turn.
Man! I don't blame you for leaving the shop with that kind of heat indoors. Sweat will rust machines almost
as fast as blood. Keep your nose drippin's off the lathe ways!

; )

Dean


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## ksouers (Jun 22, 2010)

Thanks Zee. Everybody passes, there are no failures here just problems that haven't been solved yet ;D
And we are ALL on probation... :




			
				Deanofid  said:
			
		

> It seems like certain engine types go in bunches. I guess it's the Rev. Stirling's turn.



Thanks Dean. Yeah, I've noticed that, too. We had a spate of mine engines, then it was hit-n-miss. Now it's Stirlings. Not that I mind, I like them all and it's really interesting to watch the way everybody finds a unique solution to their particular part they're making.

The machine was already well oiled when I started, but wiped down and oiled again before I turned off the lights.


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## njl (Jun 23, 2010)

Looking forward to this build Kevin. Stirlings hold a fascination for me too, one day when my skills improve enough I hope to building one. Hope you manage to combat the heat and get some building done.

Nick


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## Stan (Jun 23, 2010)

All the reading and experimenting I have done with Stirling and Stirling type engines is that the hot cap has to of a material with poor heat conduction. In the conventional Stirling the object is to reduce the amount of heat transferred to the displacer cylinder.

A lot of engines use glass for the hot end and for metal hot ends it seems like stainless steel is preferred. I have one with 660 bronze which is so-so, with a thick gasket and isolated clamp between the hot end and the displacer.


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## cfellows (Jun 23, 2010)

Stan, you've probably read all the same material I have, but I'll relay what meager knowledge I have from reading.

The sides of the displacer piston and the displacer cylinder should be as thin as you can make them to cut down on heat conductance along the metal. Also, you want the displacer piston to transfer as much of the air as possible from the hot end to the cold and vice versa, so the clearance between the displacer and cylinder should be minimal without creating drag. Steel or stainless are good candidates for both the displacer and the cylinder. Finally, make sure you have adequate cooling capacity at the cold end of the displacer. These were tidbits I got from Rudy Kouhoupt at GEARS a few years before his death.

Chuck


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## Stan (Jun 23, 2010)

> Finally, make sure you have adequate cooling capacity at the cold end of the displacer.



That is what I was referring to with the gasket isolation between the hot cap and the displacer cylinder. If the hot cap is a good heat conductor, heat travels from the hot end to the junction with with the displacer cylinder passing the heat into the cold end.

I have millions of brain cells dying daily, but I think I remember Kevin built a Jan Ridder lamina and posted all his grief on this board. He is not a beginner with Stirling type engines.


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## arnoldb (Jun 23, 2010)

Kevin, I've happily taken a seat in the peanut gallery ;D - I'm really looking forward to this!

Regards, Arnold


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## ksouers (Jun 23, 2010)

Nick, thanks for the support and welcome.

Stan, thanks for dropping by. Yes, stainless is better but that does not preclude using other steels, too. I don't have any stainless at the moment big enough to use, so I used what I had on hand. This will work well. Optimal would be a ceramic, but I'm afraid I'm fresh out of space shuttle re-entry tiles ;D
The hot end will be insulated from the cold end as much as possible. This engine is mostly being built for experimentation, I want to play with it, not just watch it run. At some point I'll use other materials and compare the performance. As the build progresses you'll see some of the flexibility built into it. I've been toying with the idea of making a water jacket for the cold end, that may come later.



			
				Stan  said:
			
		

> I have millions of brain cells dying daily, but I think I remember Kevin built a Jan Ridder lamina and posted all his grief on this board. He is not a beginner with Stirling type engines.



Right name but the wrong Kevin. That is KustomKB in BC. The only Stirling I've built was the afore mentioned tin can version many years ago. And I am a beginner with Stirlings, but I'm hoping this build will change that greatly.

Chuck, welcome, thanks for the support. And for passing along Rudy's wisdom.

Arnold, thanks. Put your feet up, get comfy and enjoy the show ;D


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## ksouers (Jun 26, 2010)

Got a little more done before the heat chased me out of the shop.

I finished the cold end of the displacer cylinder using one of the pre-drilled blocks of aluminum I picked up some time ago. I have no idea what grade it is but I dont think its 6061. It machines quite well.






Since I had to use the 4-jaw the work was done on the C2. Got it centered up on the existing hole then opened it up and reamed it to .500 inch. This job really should have been done on a larger lathe but I dont have a 4-jaw chuck for the 9x20. I didnt have much room to have a lot of cut-off tool sticking out of the holder so the fins arent as deep as the should be, but ali is a good heat sink and the cold side is really oversized so it should work out.







A relief was bored in one end for the hot cap then cut from the parent stock on a band saw, stuck back in the 4-jaw and faced the cut end.







I have a rod salvaged from an old printer that is exactly .500 diameter and it is a very close fit for the bores. The hot cap has a very satisfying pop when its pulled out. So, I can use it for a gauge when I start building the power cylinder and piston.

Thanks for stopping by.


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## Maryak (Jun 26, 2010)

Kevin,

You must have the patience of a saint to have cut those very nice fins into square stock on the lathe. :bow: :bow:

Best Regards
Bob


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## arnoldb (Jun 26, 2010)

Very nice fins Kevin :bow:

Golly man, the hole in your workpiece is 1/2" (12mm for me :big , so those fins and gaps must be about .04"  What did you use as a "parting tool" ???

Regards, Arnold


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## Deanofid (Jun 26, 2010)

Good progress, Kevin.
My, what thin fins you have... Good work on those!

Dean


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## ksouers (Jun 26, 2010)

Bob, thanks for your support. Actually, I'm not very patient at all. If you look close you'll see a bent fin where my lack of patience got the best of me. Before I even finished the first groove I was thinking "Ya know, you really should have gone for the water jacket."

Arnold, very good eye! You must have just had them calibrated! I used a standard parting blade .040 thick, the fins are .050 thick. I just plunged a groove then offset .090 for the next one.

Thanks Dean. I almost made them .030 but thought that looked a little too thin and was afraid of tearing them off. If I were to do it again I'd round the fin area first like you did.

Thanks everyone for the support.


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## ksouers (Jun 27, 2010)

Another short, hot day in the shop. Sorry about being a little short on pictures. Its just basic lathe turning, nothing spectacular about it. And its just been too dang hot in the shop. 







The power cylinder is 12L14 steel, 1.125 inches long.

I still need to do some finish work on the piston before I cut it from the parent stock, just drill and slot for the wrist pin. The power piston is 6061 aluminum and will be .625 inches long.

That should be about it for most of the lathe work. I still have the flywheel to do and there might be a couple small pieces to do later on.

Unfortunately the big mill is down for repairs. The phase shifter dealy wampus that turns house current into 3 phase threw craps a couple weeks ago, so that needs to be replaced in order to work on the plates that will hold the cylinders and drill the mounting holes.

Thanks for stopping by.


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## doc1955 (Jun 27, 2010)

I can relate to the temp in the shop. I haven't turned a spindle in a week just to hot here too plus the humidity is up.
 You have done some good looking work I need to get going on the Stirling fans I'm working on.
I stayed with square fins also hopping th gain all the cooling surface I can I know it's not much of a gain but it should help. Keep up the good work!


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## ksouers (Jun 27, 2010)

Thanks for the support, Doc. We've had the humidity too. With 3 major rivers running through here, plus a couple minor ones, there is no shortage of humidity. The heat must be getting to me. I was reviewing your build thread and when I realized there was still something I needed to do.



Well, I spoke too soon about this being the last of the major lathe work. It appears that old-timers has set in, I had completely forgotten about making the displacer piston.






So, back into the shop I go and start making the can. I cut off a piece of 1/2 inch 6061 and chucked it up in a collet and just cleaned it up taking off about 15 thou. I drilled it 29/64, that actually bowed out the sides slightly so I took a couple spring passes to clean it up. 

The walls are really thin, I dont know if they will hold up or not. Well see. After all, the whole project is an experiment so I dont mind making parts over if they dont work.


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## SAM in LA (Jun 27, 2010)

Kevin,

Nice work.

I live on the Gulf coast with all of the heat and humidity one can stand. 

You did give me an idea that may help me deal with it. :idea:

Perhaps I will have cooling fins cut into my round body. :big:

SAM


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## GailInNM (Jun 27, 2010)

Nice work Kevin.
I think that you may have a problem with the 6061 piston in he 12L14 cylinder. They have to fit so close on a Stirling that the difference in the coefficient of expansion may cause it to bind when it is up to operating temperature. Most Stirling engines use power cylinders and mating pistons with similar coefficients of expansion because of this.
Gail in NM


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## ksouers (Jun 27, 2010)

Sam, thanks for checking in. I don't think I'm ready to have cooling fins cut in me just yet :

Thanks for the heads-up, Gail. I'm not satisfied with the current parts, so I may remake them. The displacer cylinder is nice and smooth, put the power cylinder seems to have a rough spot in it I didn't find till I made the piston. So, it looks like some lapping and a remake of the piston anyway.

I have a line on some graphite that is currently in someone else's hands, but it's been tagged for rocket engine nozzles. If I end up making some of the nozzles then I'll have a piece.

Until then, do you think 12L14 for the power piston will be OK? This engine is being built with learning in mind, so I'm open to any and all suggestions. My only limit is the materials on hand at the moment.


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## b.lindsey (Jun 27, 2010)

I've been following along from the loft Kevin, but its looking good so far. 12L14 will be fine for the power cylinder but if at all possible wait for the graphite for the piston. Its light weight, thermal stability, and self lubricating properties are ideal if not mandatory on sterlings. I am worried that a 12L14 piston working in a 12L14 cylinder will require some lubrication even if well fitted and lapped, but the lubrication itself will tend to gum up with heat and without it there is the risk of galling. Keep up the nice work.

Bill


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## GailInNM (Jun 27, 2010)

Kevin,
I have to agree with Bill that 12L14 for both the piston and cylinder is not a good idea. 

I would use either graphite or cast iron for the piston. 

Gail in NM


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## Stan (Jun 28, 2010)

Brass piston with powdered graphite as a lubricant should work in a steel cylinder.


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## Deanofid (Jun 28, 2010)

Things are looking good, Kevin.
If you want to try some graphite for the piston, Jerry Howell has piston sized pieces for about $2.
http://www.model-engine-plans.com/partskits/miscsupplies/index.htm

I don't think it would hurt to try other materials, but different for piston and cylinder may be best. CI would be next choice if you don't want to go the graphite route. 
Like you say, it's experimental. You can try different pistons to see what works best for you.

The aluminum will work fine in the displacer since it has relatively large clearance with the cyl walls.

Dean


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## ksouers (Jun 28, 2010)

Thanks Bill and Gail. I figured the steel piston was a non-starter but had to ask. I was taught to always use dissimilar materials for moving surfaces, that rule has worked well through the years.

Stan, thanks. See below...

Thanks for the link, Dean. I have the graphite available, I just have to get my hands on it. The chunk is a rough 2x2x24, I only need a small piece of it. For the Terry Coss plans I have he calls out aluminum for the piston and bronze for the cylinder. I went rooting around the scrap bin and have a piece of brass big enough for the cylinder, so that is an option as well.



			
				Deanofid  said:
			
		

> Like you say, it's experimental. You can try different pistons to see what works best for you.



Yep, it's all about having fun and learning ;D
Life is pretty boring when things just go well right out of the box all the time.


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## NickG (Jun 29, 2010)

Nice work Kevin,

For my stirling I used chromium steel for the cylinder and cast iron for the piston. I lubricate it and have no problems with gumming up, oil can generally withstand a lot of heat.

On my flame gulper I used cast iron for both cylinder and piston, I also use oil to lubericate that. I tried aluminium pistons but as people mentioned the differential expansion caused it to bind up solid.

I would try and stick to the same material if I were you, then you know they are going to expand at the same rate. As already said, cast iron would probably be better than steel though due to its lubricating properties.

Good luck,

Nick


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## ksouers (Jun 30, 2010)

Thanks Nick. I guess I'll have to scrounge up some cast iron at some point.

I'm going to try the aluminum piston first, and snag a piece of that graphite. Next up would be the brass cylinder. By that time the budget should be back in line and I can put together a decent materials order.

I've ordered a new 3 phase driver for the mill, arriving tomorrow, so I'm going to have to make due with what I have on hand for the next several weeks. I'm afraid the driver has blown my hobby budget for awhile.


Thanks for all the suggestions everyone. That should keep me busy for some time to come.


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## mklotz (Jul 1, 2010)

FWIW, one of my best running Stirlings has an aluminum piston running in a 1018 cylinder. I wouldn't recommend the arrangement for an LTD but it can be made to work in engines with a good temperature differential.


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## ksouers (Jul 1, 2010)

Thanks for the confirmation, Marv. I'd been hoping you'd jump in here with a critique, or at least point out an obvious flaw when it shows up.

No, this is not an LTD, though I do plan to use an alky burner instead of propane. That should cut down the BTUs some. My hope is the alky burner will be a more consistent energy source throughout the trials.


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## mklotz (Jul 2, 2010)

All my non-LTD Stirlings run on alcohol lamps. I use the stuff sold in quart cans in the paint aisle in the home supply big-box stores. Sometimes it's labeled as shellac thinner.

If you build your own alcohol lamp, don't forget to put a vent hole in the filler cap. DAMHIKT. (Set the table on fire at one exhibition.)


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## ksouers (Jul 3, 2010)

Thanks for the heads-up, Marv. I'll be sure to vent it.

It was nice and cool this morning so I headed out to the shop to knock some things off the to-do list.

First up, the replacement VFD for the mill arrived Thursday so it was time to get that hooked up and programmed. Everything went according to plan there, it works perfectly.







Now I was ready for some engine parts. I needed to make the retainer rings that hold the cylinders down. These were cut from the same piece of stock as the cold end of the displacer cylinder. Real simple, just bore out the center to clear the hot cap, bore out a relief to catch the rim, then part it off. I couldnt get the parting tool deep enough so ended up finishing the cut on the band saw then clean up the face on the mill. I needed two of these.






.

This started out to be the bulkhead the cylinders are attached to. But the more I thought about it its too short. It doesnt leave enough room between the cylinders for any mounting hardware. Not a loss though, itll work perfect for the base. Its 2 inch by 3/8 aluminum cut 3.5 inches long then squared and faced with a flycutter.






I also got started on the plug for the displacer. I still dont have a rod, I thought I had a piece of 3/32 stainless laying around but cant find it at the moment so the plug hasnt been drilled yet.






So all the pieces made so far. I have a piece of 3mm stainless (in pic) that is a fall back if I dont find the 3/32. Or I could just run up to the hobby shop and get another piece.






And of course, I just couldnt resist doing a mock up. I need to think about that bulkhead some more to see what kind room I need.

Thanks for stopping by.


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## Deanofid (Jul 3, 2010)

Moving along pretty fast for having to think all this stuff up, Kevin.
Thanks for the assembly shot. Clears up a few things for me.

Dean


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## ksouers (Jul 3, 2010)

Thanks Dean. Yeah, I am pretty much flying by the seat of my pants, with one eye closed. And an eye patch over the other. Though I've been thinking about this off and on for 20 years I hadn't thought any of it far enough through to have a clear idea of how I was going to attack the details. I think things are going well so far for being fast and loose.


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## ksouers (Jul 4, 2010)

Some good news.

Because of the holiday and visitors I won't get any shop time today, but I did manage to steal about an hour this morning before the world comes to life. I rechecked my numbers and went back to mocking up the parts, it looks like I can use the bulkhead has planned with a minor modification. The original plan was to use two 3/8 inch stanchions but there is room for only one, however I can use 1/2 inch material. It should be strong enough.

Also, I've slowly scrapping out an old printer. I salvaged four 3/32 inch stainless pins that should be long enough to use.

Yeah, sometimes you just get lucky.


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## Stan (Jul 6, 2010)

That must be a very old printer with 3/32" components. All the computer related hardware that I have taken apart has had metric sized parts. The quality of the shafts is so good I will buy a couple of metric sized reamers to make use of them.


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## ksouers (Jul 6, 2010)

Stan,
I was quite surprised to find they were an inch dimension. I first measured them with my digital caliper set to metric, when that didn't come out even I switched it to inch, then mic'd them. I absolutely expected metric sizes.

I don't know how old it is but I got several stainless rods, dozens of springs, a couple belts and four (!) motors. Not to mention all the plastic gears I can handle. I was hoping to get some ball bearings, but that didn't happen.


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## ksouers (Jul 10, 2010)

I got nearly a full day in the shop today. I didnt think Id gotten much done until I started putting together the items for pictures.

Most of the time was spent drilling and tapping holes. 27 holes drilled in 4 parts, 12 holes tapped in two parts. All the holes are either tapped or clearance drilled 4-40, except where they aren't ;D






The bulkhead was drilled and tapped to mount the retainer for the power cylinder and clearance drilled for the cold end of the displacer. The displacer side was drilled #42 in the center for the displacer rod. The cold end of the displacer cylinder was drilled and tapped both ends. Then a 3/16 end mill was used to drill into the cold side .150 and a slot milled. The bulkhead will be drilled through the end near the viewer in this picture to the slot, then tapped and plugged.






It turned out to be a rather productive day. The flywheel is finished, 2.250 in 1018 steel. The plug for the displacer piston was finished, the piston still needs to be assembled. The rods were cut and brought to size and the bearing standards were rough cut.






And everything roughly in its final position. It's awful silvery, I need to figure out how to fit some brass in there somewhere :

Thanks for dropping in.


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## zeeprogrammer (Jul 10, 2010)

ksouers  said:
			
		

> All the holes are either tapped or clearance drilled 4-40, except where they aren't



Nice.

A whole day in the shop? Lucky guy.


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## Deanofid (Jul 10, 2010)

A day in the shop, and it shows, Kevin. There's a point where all of a sudden, bang! It looks
like a whole bunch got done at a whack. I think you're there, and it's looking promising!

Dean


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## ksouers (Jul 11, 2010)

Thanks Zee. Yep, I got tired of those itty bitty 2-56 threads and wanted something a little more hefty.

Thanks Dean, but today I hit the wall. Spent a goodly amount of time but little to show for it.


Not much to show today for a fairly lengthy session in the shop. I lost a lot of time making a messed up con rod for the power side. Actually, the mistake was made rather quickly, as usual, but only after putting a couple hours into it.








My original plan was to make some crank arms out of aluminum, but the engine is looking way too silver and needed a little color. So, I decided to make a couple crank disks ala Elmer out of brass. I still need to clean them up some; theyll be locked on the axel with grub screws so I can play with the angle between the two pistons. The boogered up con rod is in the background, remake in the front. I also finished up the power piston but forgot to include it in the group shot.

Thanks for looking.

P.S: As a side note, I see a lot of beautiful pictures. The focus is great, color, lighting, depth of field, composition. Everything is perfect. On the other hand mine all look washed out and crappy. Could one of you guys offer up a thread on taking pictures? 

Ive got a good camera, Canon EOS Digital Rebel SLR, but I seem to get better pictures with my old Kodak point-and-shoot.


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## mklotz (Jul 11, 2010)

Ken,

Actually, I think your photos look pretty good.

Photographing shiny metal objects is tricky at best.

Here are some hints in no particular order...

Don't photograph parts on a shiny black surface plate. Use a single color, unpatterned cloth with a fine, unobtrusive weave. Darkish blue is a good choice. Avoid bright colors.

Check the white balance on the camera. The auto setting isn't always the best. After setting up the lighting, cycle through the available white balance settings while watching the color of the background cloth. If you can't get a true color, you may have to use the camera's custom white balance setting.

Use diffused lighting to minimize "hot spots" and reflections. If you want to go over the top, build a simple light box - cardboard box with large windows cut in top and sides, said windows covered with cheese cloth diffusers.

Use a small aperture setting to maximize depth of field. This will necessitate a longer exposure so a support for the camera may be required.


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## ksouers (Jul 11, 2010)

Thanks Marv.

Yep, I've tried all those things except the blue background. White balance is set with a stack of several pieces of printer paper to avoid any shadow bleed through. 

I've tried moving lights around; diffuse, reflected and bare light; ASA from 200 through 1600.

I've had the best luck closing down the aperture. 

Unfortunately getting away from the auto focus is difficult. The lens is very awkward to focus manually, and my vision is not great. It's the lens that came with the camera when purchased. I'm loathe to blame the machine but perhaps an aftermarket model is needed. I've seen some very wonderful macro shots of corals with this same model camera but a different lens.

I don't have any fabric handy but I do have some blue paper towels to try for a background. It seems better, still it appears to me that some details are washed out. In particular the crosses on the phillips head screws and some chatter on the inside lip of the cylinder. I'm more readily to believe the operator is the problem rather than the camera.






As examples of what I'd like to achieve I offer up:
http://www.homemodelenginemachinist.com/index.php?topic=8169.msg89167#msg89167

http://www.homemodelenginemachinist.com/index.php?topic=8768.msg94104#msg94104

http://www.homemodelenginemachinist.com/index.php?topic=8897.msg106001#msg106001


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## mklotz (Jul 12, 2010)

Try a darker colored cloth. It doesn't have to be blue - that was just a suggestion, not a dictate.

Diffuse the light coming from the left and add a (maybe weaker) source of diffuse light on the front of the subject.

Most Canon cameras have an autofocus lock feature. That may help you to solve the focus problem.

It takes time and a lot of experimentation. Also, I'm hardly an expert photographer. Check some of the books written by the professionals.


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## Deanofid (Jul 12, 2010)

I'm pretty much on Marv's side of the fence, Kevin, in that your photos don't look
as bad as you seem to feel they are. 
The shop is kind of a hard place to light for photos. Often shiny stuff, that wants
to flare, and then some dark corners where detail is lost.

You mentioned that you felt you often did better with your point 'n shoot. That very
well could be, and there's a good reason if it's true. The depth of field on that kind
of camera is very deep relative to the lens, and so puts a lot of things in focus. 
Shooting close up on your EOS may actually involve a magnification factor, and camera
movement becomes more evident.

For which ever camera you use, force it into macro mode as long as you're closer than 
about 2.5 ft. Most cameras have an option to use a single center point 
reference as your focus point. I set mine to display in the center of the finder, and
always put that point on what I want to be critical focus.

Leave the flash off. (It looks like you do that already.)

Set the color balance to a white sheet each time you change your lighting. Put that
white sheet in the same place your are going to be doing your shooting when you set
the balance.

Most of our shops don't have diffuse lighting, because we prefer bright direct light 
while we work. You might just look around the shop for a place where light is falling
from multiple directions and take your photos there. For taking them while your parts are 
on your machines, you're stuck with what you have, but a couple of large
white pieces of card or poster stock will make a good soft bounce to fill in some of 
the dark corners.

Dean


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## Troutsqueezer (Jul 12, 2010)

Hi Kevin, I think your pictures look good. 

The camera I used in your examples has a large lens and is fairly expensive. Small cameras with smaller lenses won't capture as much detail nor light despite pixel count. 

I use a mixture of light for my photos. Sometimes a sharp light directed from a particular angle will show off the metal highlights well, used in conjunction with an LED lamp, a swing arm incandescent and overhead florescent (std shop lighting). 

It's all a balancing act. 

-Trout

<edited for clarity>


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## idahoan (Jul 12, 2010)

Dean

I have seen you make reference to the white card camera set up in other posts; could you please elaborate a little more?
I have two digital point and shoot cameras that I use in the shop; Pentax and Canon. I always seem to have mixed results with them.
I wonder if this technique may also help my picture taking in the shop.

Thanks,
Dave


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## ksouers (Jul 12, 2010)

mklotz  said:
			
		

> ... It doesn't have to be blue - that was just a suggestion, not a dictate.
> ...
> It takes time and a lot of experimentation...



Thanks Marv. I took it as such. My choices were blue or white towels. I'll have to see if my wife has any fabric squirreled away somewhere, or find some colored construction paper.
Bytes are cheap 


Thanks Dean. Actually the corner I use for pictures is very poorly lit from the overhead lights, so almost all the lighting for pictures is from the floods arranged for the task.


Thanks Trout. The camera wasn't cheap, but it's toward the lower end of Canon's DSLR line. The camera was selected after seeing some amazing macro shots of corals, but sadly all his pictures have disappeared. 

Due to those pictures I know the camera is capable of taking great pictures, so I'm left with operator error as the culprit.

I'm familiar with the basics of camera operation; aperture, shutter speed, "film" speed and such. I guess what escapes me is the art of taking pictures rather than the pure mechanics of it. I think I was hoping to gain some insight into the artistry, probably something you folks do automatically without thinking about it.

Jackson Pollock splatters paint on a canvas and it gets called art. I splatter paint and people ask if I've had an accident ??? I have no artistic talent but certainly recognize it when I see it. I just can't duplicate it, and that's what frustrates me.


The place where I take the pictures is my marking and layout area, not really conducive to taking pictures but it has convenient power outlets and purchases for the lights. When I stage a photo shoot I take about 50-60 pictures, I may find one or two that I find tolerable or less objectionable than the others.

I'll have to see about constructing a light box.

Thanks guys, for all the suggestions. I appreciate the time taken to help me on this.


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## ksouers (Jul 24, 2010)

A minor update, but no pictures yet. I'll have some tomorrow.

It was very hot today, the shop was 95 at 8:00 this morning when I started. By noon it was over 100 inside! Still, it's been a relatively "cool" summer, we haven't officially broken 100 yet. But 75 straight days of 95 is a bit unusual.

Anyway, I started on the base. I needed to start anchoring things down. Cut a piece of ali and got is squared up and fly cut the faces to make it pretty. Drilled the holes to mount the bulkhead and drilled and tapped that as well. Put it together for a test fit and looks great. Checked it with a machinist's square and it is spot on.

I got all my measurements and calculations together for the bearing standards mounting holes and proceeded to center-drill and through drill all the holes. First up, I noticed one of the holes looked to be in the wrong place. Double checked, yep, it's off. The hole isn't in a critical place so I left it and continued with the rest. It looks beautiful. It looks great. All shiny and gleaming. It's also completely wrong!

It seems when I was setting up and zeroing in the edges I forgot to take out the edge finder radius on one side. Stupid me. The brain gets addled with age, and the heat just turns what is left into mush. Tomorrow it should be cooler, there is a front moving in tonight, so I can plug the holes and start over.


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## Deanofid (Jul 24, 2010)

Gosh, way to hot for too long, for me, Kevin. Hard to work that way. When it gets into 
the 90s here, I have to pack it in. Thankfully, we only have a few weeks of 90-100° f here,
and when it's past, I can get to the shop again. Most folks here have no form of AC, including
me. Hope things cool down for you soon!

I suppose we all do that with edge finders, now and then. It happens. Sometimes, when I
have a crazy amount of holes to do, I put Sharpie dots at each one so I know if I've lost
count, or forgot to start on the center of my edge finder or wiggler.

Oh well. It's easy enough to plug a hole in aluminum! Still a pain in the breeches.
Didja get that chunk of graphite?

Dean


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## zeeprogrammer (Jul 25, 2010)

I've forgotten the edge finder radius often enough that I've finally developed the habit of moving he edge finder down to the part to double-check by eye. The radius is large enough to see I'm off.

I wish you'd get some AC Kevin. With global warming it's just going to get hotter and stay hot longer. : You need the shop.


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## Deanofid (Jul 25, 2010)

zeeprogrammer  said:
			
		

> With global warming it's just going to get hotter...



Hey! I thought we weren't supposed to talk about religion on this forum...

Dean


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## ksouers (Jul 25, 2010)

Thanks Dean. I usually avoid the shop this time of year unless I just HAVE to make something. Normal shop time is an hour or so Saturday morning just to clean up a bit and get ready for the comfy weather. But this stirling has been gnawing at me for years and now that I've started it I have to finish it. I guess I'll have to change my name to Ahab and call the engine Moby ;D

Thanks for the concern, Zee. It really is appreciated. Wife and I (that's her name, "Wife"  ) have discussed putting A/C in the shop. We did again this morning. She left a couple hours ago to go shopping, though she didn't say it, something tells me she's going to come home with one.

Actually, Zee, we are running a little cool for this time of year. The heat broke a little today and it only got up to the high 80's. We usually have a couple weeks touching the 100's by now. Last summer was very mild with only a few days in the 90's. Really what is changing is my tolerance of the heat. I can't take as readily as I could when I was younger. Each year seems tougher to deal with.


On to the project...
I plugged the holes in the base and redrilled them. Got it right this time, though one of the plugs came out while drilling. The proper location just touches the old holes, so there is a little bit of overlap. Spent the rest of the morning tweaking everything since I finally got to test assemble things. Then a break at noon to go spend a few hours in the air conditioned house ;D

Then a short session for some more fiddling and started whittling on one of the con rods.

Yippee!! I got things that go round and round now!

Sorry for the crappy pics. I was too hot, tired and cranky to set up for staged shots. I took some outside in the sun but they were even worse than these. I just took some shots on coffee table on full auto.

















Thanks for stopping by.


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## deere_x475guy (Jul 25, 2010)

Kevin, I too struggle with quality pics and purchased a DSLR in March. I expect to be a grandfather someday and I think it's not far off and I wanted better pics of the shop projects. My problem is I just don't take the time to stage the shots and use total control of the camera. ISO, aperture, shutter speed, whitebalance and focus all come into play....

I am following along on your project and learning while I read. Thanks for taking the time to document it!


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## ksouers (Jul 25, 2010)

Thanks for stopping by Bob. If you're looking to learn how to make mistakes you've come to the right place!

We've had the DSLR for a couple years now and I'm just beginning to learn how to use it. My wife is the photographer of the family taking thousands of pictures a year. She has a Canon AE-1, but film has gone the way of the dinosaur so I picked up the Rebel for her one year at Christmas.

I took photography classes many decades ago but unfortunately I've never really had the eye for it. The Canon is really tricky to work, you have to push this, then hold that while twiddling with this little wheel. It has auto settings but I don't really like the results so I've been fiddling with the manual settings. 



Dean, I almost forgot. I talked to my rocketry buddy and I can grab a chunk of graphite whenever I need it. He lives just around the corner so it'll be easy to get hold of.


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## deverett (Jul 26, 2010)

zeeprogrammer  said:
			
		

> With global warming it's just going to get hotter and stay hot longer.



I'm still waiting for global warming to reach Ireland. All we seem to get is plenty of 'liquid sunshine' from on high.

Dave
The Emerald Isle


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## njl (Jul 26, 2010)

Kevin, that's coming together very nicely, you'll soon have another engine done.

Dave if you've got any of that liquid sunshine to spare we could do with a drop here in Twyning Gloucestershire, things are starting to get quite dried up and our sheep are getting short of grass. 

Nick


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## kustomkb (Jul 26, 2010)

Looking good Kevin. 

I have been following along and look forward to the final vid.


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## Deanofid (Jul 26, 2010)

Neat, Kevin! Suddenly it looks very... engine-y. You know what I mean!


Dean


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## ksouers (Jul 26, 2010)

Dave, thanks for stopping by.

Nick and Kevin, thanks guys. It won't be long now. Just a few more widgets to make and some minor details and it'll be ready for a test run.

Dean, yes I know what you mean ;D It's no longer just a collection of oddball parts, it now has context. It's got parts that move, and they move other parts and you can wiggle them and watch them do their thing ;D


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## Groomengineering (Jul 27, 2010)

Hey Kevin there's more work to do, no time for sitting around wiggling pieces and making vroom vroom noises...... like I do... :big:

Looking good! There's just something about a Sterling...

Cheers

Jeff


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## ksouers (Jul 27, 2010)

Thanks Jeff.




			
				Groomengineering  said:
			
		

> ...sitting around wiggling pieces and making vroom vroom noises...... like I do... :big:



I call it part of the break-in process ;D


Ain't it amazing? Just heating and cooling a sealed volume of air can cause things to move. What's really amazing is that it happens so quickly.


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## njl (Jul 28, 2010)

ksouers  said:
			
		

> Ain't it amazing? Just heating and cooling a sealed volume of air can cause things to move. What's really amazing is that it happens so quickly.



Yep I find that totally amazing too. We have a model engineering show near Bristol each year and it usually has a good turnout from the sterling builders. Some of them go at quite a speed. I find them fascinating to watch. One day (soon I hope) I will have a play with building a sterling, your build thread is giving me inspiration.

Nick


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## ksouers (Jul 28, 2010)

Go for it, Nick! It's been a fun build. Though for me this particular project has been more of an obsession.



A bit of an update.

I needed to get some dimensions by direct measurement, but the point to measure from didn't exist yet. So, I found a couple pieces in the "bits o" box, you know bits o this and bits o that. Just a couple pieces of aluminum. Any way, made my mock up part and fitted it. Got my measurement and made a quick and dirty con rod and rod end for the displacer and fitted them, checked out the range of motion. Everything was moving at it should, no binding or interference. My numbers were good to go.Then I thought to myself, "Self, you can use that." And so I did.

It was time for a test run. Made some quick and dirty gaskets from some card stock I had laying around. Assembled everything but didn't hook up to the flywheel just yet. Moved the piston in and out, the displacer also moved in and out. Good, no leaks, or at least very little.

Hooked up the con rods to the flywheel and left the plug out that seals the channel drilled between the cylinders. Everything moves freely, the flywheel makes a couple revolutions before stopping when turned by hand. Low friction, but of course, not real low. With everything plugged up it'll just barely turn over by hand due to compression.

I used a propane torch for heat. Of course, no joy in the running department. At this point it could be any of a number of things. 

First up is friction, of course. I'm using plain bearings at the moment, I have ball bearings on order, should be here in a day or two. 

Heat, there seems to be an inordinate amount of heat transferred to the frame. The hot cap is pretty short and it's possible the torch was heating everything up, but I'm also quite sure there was a lot of conduction from the hot cap to the frame. I'll add a deflector to help keep heat away from the cold side and frame. Also, some better gaskets to help reduce the conduction.

Timing. Yep, still need to work on the timing. I don't remember if I had the displacer leading the piston or not. I need to check that out, though I it seemed to have a preference for wanting to go one direction over the other.

Anyway, those are the first things I'm going to attack. I didn't expect it to run, but it would have been great if it ran for a few seconds. I did collect (subjective) data, which is what I really wanted to do, I consider the first test a bit of a success.


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## njl (Jul 28, 2010)

Kevin, you could try putting some ice on the cold end and repeating your test, that would give you a bigger pressure difference which might be enough to overcome the friction or reduce the effect of heat leaking into the frame.

Nick


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## mklotz (Jul 28, 2010)

I wasn't going to say anything but since you brought it up... the displacer chamber looks a bit short. You may want to take a look at these suggestions from James Rizzo...

http://www.homemodelenginemachinist.com/index.php?topic=5951.msg63174#msg63174

The chamber should have thin walls to minimize heat conduction and be made from a relatively poor conductor such as steel.

The displacer should be a close fit in the chamber. The displacer acts as a regenerator and a close fit means more turbulence and better heat transfer as the air moves past the displacer during the displacer stroke.

Piston and displacer should be ninety degrees out of phase with each other. Use that as a starting point and diddle after you get it running. If it won't run with that phasing, it probably won't run at all.

I'm sure you'll make it work. I'm looking forward to the video since I'm a real fan of Stirlings.


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## Deanofid (Jul 28, 2010)

Kevin, I have some good insulator stuff here. Same stuff used in the last one I built. 
It's sheet, 1/16" thick, non-asbestos ceramic. If you want some, send your address and I'll
put a piece in an envelope and send your way. 
I have plenty of it.

Dean


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## doc1955 (Jul 28, 2010)

ksouers  said:
			
		

> Moved the piston in and out, the displacer also moved in and out.




To me it sounds like your displacer is just a little to close fit. The air needs to move freely from one side of the displacer to the other. And if you move the power piston which I believe you are saying and the displacer moves then most likely it is much to close of a fit.


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## ksouers (Jul 28, 2010)

Thanks Nick. I did contemplate dripping cool water on the cold end last night. I do plan to do that sometime in the future. I'd also like to make one with a water jacket, but that's for a later project.

Thanks for reminding me of that link, Marv. I had used Rizzo's "guidelines" when I started building this engine. Though it looks like the one I missed was the swept volume of the displacer, mine is 1:1 vs Rizzo's 1.5:1 with the power piston. I thought the hot cap looked a little short when I made it, but I've also seen successful engines running with small caps. 

One of the things I wanted to play with was the length of the displacer cylinder, so looks like that is going to happen rather quickly. I will also have to adjust the stroke, but I've made allowances for that with over sized crank disks. The displacer is .010 smaller than the bore, so I've got a close but not tight fit.

I knew the pistons would be 90 deg out of phase, I just couldn't remember which was supposed to top out first, thus no idea which way to spin it to get it started. I tried both directions, one seemed more willing to run than the other. Or is that one way was less willing, since neither way worked?

Dean, thanks for the offer, I'll definitely keep it in mind. I have a couple ideas I want to try first. At the start I had planned to use some high-temp RTV between paper facings as the gasket, I still want to try that.

As stated at the outset this engine is for experimentation and I mean that in the most serious way. While I have ball bearings on the way, they won't be installed immediately. I want to try things that are maybe a little different. So even failures are a success as long as I learn something from it. The one epithet I wear proudly is "stubborn, hard-headed German" ;D

Thanks Doc. I plan to try many different things, even after the engine is running. Including different fits for the displacer.


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## mklotz (Jul 28, 2010)

I checked my Stirling of that type and, when the piston is at TDC, the displacer is at mid-stroke and moving towards the cold end of the displacer chamber when the flywheel rotates in the "running" direction.

Ten-thousandths clearance (I presume that's 0.005" all around) seems a bit small but I'm not an authority. Give it a try and, if it doesn't run, try a bit smaller diameter displacer. However, I would try a larger displacer volume (longer displacer) first.

Good luck from another hard-headed German.


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## doc1955 (Jul 28, 2010)

I think .01 is not sufficient clearance for the displacer I'm thinking you'll need to open up the cylinder and give it about .03 clearance. Going with to close a fit will put more pressure that the motor will have to over come as it is trying to squeeze the air through a .005 gap.


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## ksouers (Jul 28, 2010)

Thanks for checking the direction, Marv. Is that with the top of the flywheel running towards the back? That's the way I'm set up, the displacer is leading the power piston by ~90 degrees when the flywheel is rotated back and down.

I double checked the displacer diameter: .4877, the cylinder is .500 as checked against a ground shaft that is .4995


OK, next attempt with a 1/2 inch longer hot cap, 1/4 inch longer stroke on the displacer. Regardless of success or failure I'll also make a smaller diameter displacer.

Thanks for the suggestions, guys.


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## NickG (Jul 29, 2010)

My 2p worth - as others have said and this backs up your remedial action, first 2 things I noticed were - 

1. compression ratio is too high, there should be very little compression. 1:1 is good for efficiency but you'd need a lot of heat and good cooling. Generally, the bigger the ratio of swept volumes from displacer to power piston the less heat will be required. I did exactly the same on my first stirling, it was easier for me to increase the bore of my displacer. When doing so, I also lengthened the hot cap and displacer as you are thinking of to lessen or slow down heat transfer between hot and cold ends.

2. Clearance between displacer piston and cylinder is too small. If you move the power piston, the displacer should not move on its own, the air should displace around it. I think a ring bom type engine works by having a tighter fit and the air moving the displacer piston, but you don't want that, you want a clearance to minimise any loses whilst not being too large. My clearance was about 1/32" all around on a 1/2" dia displacer piston, so a lot more than yours. This very small clearance might account for some of your high compression.

3. the usual stuff, minimise friction, with the hot cap off, the thing should spin over for quite a few revolutions, I would say at least 10.

Hope everybodies input helps, sure you'll have it running soon with your proposed changes.

Cheers,

Nick


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## ksouers (Jul 29, 2010)

Thanks NickG.

I remember your first stirling, going through similar tribulations. Seems like ages ago now. You followed that up with a very nice LTD.


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## mklotz (Jul 29, 2010)

ksouers  said:
			
		

> Thanks for checking the direction, Marv. Is that with the top of the flywheel running towards the back? That's the way I'm set up, the displacer is leading the power piston by ~90 degrees when the flywheel is rotated back and down.



Exactly.


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## rleete (Nov 21, 2010)

Bringing this one back from the dead, as I've been bitten by the Stirling bug.

Whatever happened with this build? It seems just as the weather broke, the progress halted.


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## ksouers (Nov 22, 2010)

Hi rleete,

Thanks for the interest ;D

It'll come back, I just haven't had time to hit the shop lately. About the time I stopped to wait out the heat I started a big project at work that should wrap up in a couple weeks. Then back in September I was given responsibility for 60+ Linux computers that belong to a sister company on the mid Atlantic coast. The machines and software are old and out of vendor support, so it's been a busy time to get everything back up to date. On top of it all, that data center is to be relocated about 100 miles further south, so it'll start all over again some time next year. These 18 hour days are starting to drag the old man down.

Fun times here in the midwest :

I'm hoping to get some shop time between Thanksgiving and Christmas. Maybe.


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## Longboy (Nov 24, 2010)

.......I just read all 5 pages here on your build. I agree with others here that your displacer clearance to the hot cylinder is just way too tight. Closer is not better here in Stirling. I build with a displacer clearance of .040. In this case a source for friction is drag in the cyl. by the displacer. The engine may be pumping the air rather than shuttling air back and forth. Give it a look/see for scuff marks on your displacer. The gland bushing looks long enough in the photos but the clearance for the pushrod to pass thru can give the displacer some out of parallel sag traveling in the bore. Oh, tell the guys at work, "tahellwithit, I got engines to build"!    Dave.


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