Christmas Stirling 2011

[shred]

I won't be posting finished pictures just yet, on the off chance the recipients are on here (unlikely, but you never know), but the Jan Ridders Stirling Bas I made last year was very well received, so I made another Ridders design for a present this year. I modified the design just a little to fit materials and skills on-hand.

Here's some in-process photos. More tomorrow I think

Trepanning out a nice circular slot to fit the displacer cylinder. You can see my makeshift chuck spider behind (a chunk of stock of appropriate length, faced off and trimmed to fit the chuck through-hole behind)

Displacer rod parts. To avoid threading each end #2-56, they are tapped and short lengths of screw are glued in with Loctite 620

The design has the fork going into the bushing, so the fork has to be flush with the rod (you are probably better making the connecting rod a tiny bit short versus long). Chucked up in an ER-20 collet holder and stuck in the 3-jaw, this isn't ideal, but worked for the task at hand.

All done

Loctite #620.. as long as the parts are clean, once it sets, they're together forever unless you apply serious heat and torque. Most of this engine is stuck together with this. The crankshaft has taken a few whacks and drops and wobbles a bit, but is still tight.

The crankshaft jigged up, waiting for the 620 to set up.

 

[shred]

Well, it was delivered late and USPS broke it :redface2: so it's coming back to be fixed, but here's a few more pictures and a video from when it was here.

The design is from Jan Ridders "Egg Cup Stirling", but I added miniature ball bearings for the axle, changed up the crankshaft and did the displacer tube from glass so it would withstand the heat of a tea candle. It will overheat if left running for a very long time (hours +), but works well otherwise.

One thing to note with the ball bearings (which I really like otherwise) is unless you change the pillar construction, there's no way to remove the crank without removing the pillars, which are held in from inside the displacer. As that's glued together with silicone, you need to make sure it's good before sealing it all up. Were I to do this again, I'd think hard about either changing the mount or putting bearing caps on the pillars.

Here is is being glued together--

And a poorly-lit video

[ame]http://www.youtube.com/watch?v=lQ3SpblzXhQ[/ame]

 

[nsfr1206]

Looks great. Nice touch with HMEM logo on computer

 

[Blogwitch]

Roy,

Jan sent me this picture to show how to get over the burning of the clear plastic tube.

When eventually I get my 3 finished, this is the way I will do it.

John

 

[shred]

That would be good if you are using a plastic displacer as well. I tried Lexan but it drooped in the heat, so switched to copper-clad PCB material, which works great. The glass from the candle lantern works pretty well, but you have to allow it room to expand or it will crack.