Author Topic: Howell Stirling Engine Fan  (Read 6277 times)

Offline bent

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Re: Howell Stirling Engine Fan
« Reply #15 on: January 05, 2022, 08:20:00 PM »
Nice work!  I'm a bit surprised you didn't get a lot of flexing and tapered cuts when re-cutting the fins, but you are likely more careful than me.  LOL

Online crueby

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Re: Howell Stirling Engine Fan
« Reply #16 on: January 05, 2022, 08:47:33 PM »
Great job!   I'd be terrified of interrupted cuts like that on such thin fins, came out great!

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #17 on: January 06, 2022, 01:07:41 AM »
Bent, Chris, Thanks guys!

I'll admit the fins aren't perfect, but with a sharp tool, light cuts, and an easy-does-it feed rate, we all survived.
Regards,
Ron

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #18 on: January 11, 2022, 12:29:07 AM »
After all the work cutting the fins on the displacer cylinder, I moved on to the displacer connecting rod for a nice change of pace. Unlike the cylinder, this is a fairly small piece, but like it a number of steps were involved.

Work commenced with drilling the big and little end crank pin holes. While I was set up I also cut in the 1/8” slot that “decorates” the web. Then it was taken down to the specified major width.




The following steps were much simplified by making the simple mounting fixture shown here. After cutting the part free from the stock, the “scrap” was used to make the fixture. This allowed me to easily clamp or screw the part to the table or the face plate. The pins keep it aligned and allow for easily flipping it over to work on opposite sides.


The fixture was mounted to the mill table at a small angle (~2 degrees) for cutting the tapering shape of the sides of the web. It was a simple matter to just flip the part on the fixture to cut the same angle on the other side.






With that done, the fixture was mounted to an angle plate so the web between the big and little ends could be thinned down. I must have either staged the picture below “post-production” or there is a strange parallax effect in the photo, since the angle plate seems to not be aligned with the table very well! In any case, I know it was set-up properly when the cuts were made.


Now the fixture got screwed to the face plate and mounted on the lathe, where a big end boss (Big Boss?) outboard of the web was turned.


Two sets of filing buttons were made up for the final rounding of both the big and little ends. I just realized that I didn't take any photos at all of the work done at the little end (sorry, little end).


And the finished connecting rod.

Regards,
Ron

Offline Bear

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Re: Howell Stirling Engine Fan
« Reply #19 on: January 11, 2022, 12:32:36 AM »
 :ThumbsUp:

Online Kim

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Re: Howell Stirling Engine Fan
« Reply #20 on: January 11, 2022, 05:43:14 AM »
Great work, Ron!
Lots of work goes into that part, doesn't it?!

Kim

Offline Flyboy Jim

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Re: Howell Stirling Engine Fan
« Reply #21 on: January 11, 2022, 02:01:24 PM »
That's a great looking part Ron. Thanks for taking us on the journey.

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline bent

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Re: Howell Stirling Engine Fan
« Reply #22 on: January 11, 2022, 06:24:09 PM »
Nice connecting rod, as others said that was a lot of work, but looks worth it. :popcorn:

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #23 on: January 12, 2022, 12:08:23 AM »
Thank you guys!
Yes, a fair bit of work in that part, but satisfying. As Bill Watterson/Calvin said - "It's only work if someone makes you do it."

I didn't take any pictures of the false starts on set-ups, or the glazed eye pondering...
Regards,
Ron

Offline Art K

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Re: Howell Stirling Engine Fan
« Reply #24 on: January 12, 2022, 04:28:10 AM »
Ron,
I've been following along, not said much. Nice work! I had a notion to make the Moriya fan for my uncle, bought the book and everything. Unfortunately that's as far as I got.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #25 on: January 12, 2022, 03:44:21 PM »
Hi Art, and Thanks!
The Moriya fan looks like a good project too, similar to the Howell in layout.
Regards,
Ron

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #26 on: January 14, 2022, 01:07:53 AM »
The next parts I tackled are the Bearing Standards. After fly-cutting two plates of 1/8” aluminum to 0.94”, they were fastened together so as to be machined as a pair.


The standards get three holes drilled into the face. The lower two are decorative only, while the upper one carries the ball bearings for the crank. See the center-dimple to the right of the SHCS? It wasn't until I had already drilled and “reamed” (using a 3/8” end mill) the bearing hole, that I realized it was in the wrong place! It is meant to be 2.61” from the baseline at the left. To avoid possible counting confustion when cranking that far, I like to do the big round number first, then do the additional smaller amount. This time I duly cranked 40 turns to get to 2” and proceeded to make the hole. Completely spaced out on the  0.61” bit. DUH!  :facepalm:

Fortunately for me, I was able to start over without moving the piece by working “top down” instead of  “bottom up”. The larger, lower, decorative hole just swallowed up my mistake. The only visible evidence is the other center-dimple, and that will be hidden by the crank. Whew!


With that disaster averted, I used the same fixture as before, but with a bushing over the pin to fit the bearing hole, to cut the angled sides.


And another set of filing buttons (I found this pair ready for use in the junk drawer) to round off the end.


Finally, the two pieces were separated, and the tapped 4-40 holes used to screw them together at the lower edge were then used to match drill the Displacer Head. I like to use the shank of the tightest fitting drill that will go in for lining up jobs like this. In this case the #43 tap drill does the trick.



Regards,
Ron

Online crueby

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Re: Howell Stirling Engine Fan
« Reply #27 on: January 14, 2022, 02:09:47 AM »
Quick thinking qnd a nice save!


 :popcorn: :popcorn: :popcorn:

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #28 on: January 14, 2022, 03:03:55 PM »
Thanks Chris!
I'd have to say ssss---ll---oo---wwww thinking is closer to the truth.   :noidea:
Regards,
Ron

Offline Bear

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Re: Howell Stirling Engine Fan
« Reply #29 on: January 14, 2022, 04:16:39 PM »
Coming along very nicely.