Moriya Stirling Engine Build

[GlennW]

Very nice looking parts.

Well done!

[rmac]

Very nice looking parts.

Well done!

Thanks! As near as I can tell, the holes are even in the right place.

-- Russell Mac

[Harold_V]

Very nice looking parts.

Well done!

Indeed!
In regards to spindle speed, a great deal depends on the lathe in question. If you have a reasonably rigid machine, you can increase speed considerably. The negative aspect is usually just chatter, but even that can be overcome by proper feed rate. If you wish to try, and you get chatter, increase the feed rate. If you take it in steps, you may just find a place where it works well. Lubrication is important, although you could probably get away with creating those grooves by cutting dry with 2024 aluminum. In the heat treated state, it cuts quite freely and tends to resist chip welding on the tool. I wouldn't try it, but it should work.

H

[rmac]

I don't have any problem supplying lubricant ... Home Depot sells WD-40 by the gallon! I was mostly wondering how to do those cuts faster.

By "chatter", are you talking about chatter during the time the tool is actually cutting? Or are you talking about the 4-times-per-revolution impact on the tool every time it starts another section of the interrupted cut in the square part?

It took me a long time, but I finally did figure out that the parting tool sometimes works better with more aggressive feed.

-- Russell Mac

[Harold_V]

By "chatter", are you talking about chatter during the time the tool is actually cutting? Or are you talking about the 4-times-per-revolution impact on the tool every time it starts another section of the interrupted cut in the square part?

Yes, the actual cutting time. You most likely won't get any while the cut is interrupted, although there will be a pattern develop due to the loading and unloading of the cut. That condition usually goes away the moment the cut is no longer interrupted.

It took me a long time, but I finally did figure out that the parting tool sometimes works better with more aggressive feed.

-- Russell Mac

It takes a little courage to think beyond light cuts, but a heavier cut often provides for better chip flow, and the added load on the tip can decrease the tool's ability to move, thus chatter is eliminated.

H

[rmac]

It takes a little courage to think beyond light cuts, but a heavier cut often provides for better chip flow, and the added load on the tip can decrease the tool's ability to move, thus chatter is eliminated.

Yes. Besides requiring a little courage, it was totally counterintuitive to me. Usually when things aren't going well, it's not the time to double down on whatever it is you're doing.

-- Russell Mac

[NP317]

Excellent work on those finned cool-end cylinders!!
And your slow turning technique sounds very familiar. Patience = good results.
RussN

[rmac]

Excellent work on those finned cool-end cylinders!!

Thanks. Even my wife thought they were pretty.

I noticed that your engine has five thicker fins instead of seven thinner ones like the plans show. Do you remember why you did it that way?

-- Russell Mac

[NP317]

Excellent work on those finned cool-end cylinders!!

Thanks. Even my wife thought they were pretty.

I noticed that your engine has five thicker fins instead of seven thinner ones like the plans show. Do you remember why you did it that way?

-- Russell Mac

Russell:
My fan was a gift from the students who built it.
For reasons lost to history they chose the thicker fins. It could have been tools available, and setup oddities.
Or their lack of patience... Finals week fast approaching?
I can only guess.
I like your work better.
RussN

[rmac]

I like your work better.

I agree that mine looks better, but I guess the real question is which version dissipates heat better. There's probably some optimum fin-to-space ratio that depends on all kinds of things. I'm not gonna worry about that.

Progress Report #5:

Two more little parts are done as of this morning. These are the top covers for the displacer cylinders. The tricky part for me was figuring out how to hold them while turning the round part. They're only 3/16" thick, so grabbing them with the tips of the chuck jaws would have been kind of iffy.

I wound up attaching them to a larger piece of metal by running screws in from the back into smaller, threaded versions of the four mounting holes. Then I could grab the larger piece of metal with the chuck, do the turning, and enlarge the mounting holes after the fact.

-- Russell Mac

[NP317]

Looking good.
RussN

[rmac]

Progress Report #6:

Two more parts done. These are the power cylinders. I made them sort of like the hot end of the displacer cylinder, only with some thick wall bronze tubing instead of steel. Since neither the tube OD nor the flange thickness is critical here, I was able to machine away all my big gobs of silver solder so they look decent.

This was my first time turning bronze. The chips were kind of weird--more like dust than the strings of material that I'm used to with aluminum or steel. The finish came out pretty nice, though, so I guess I'm happy.

-- Russell Mac