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

Offline bent

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Re: Howell Stirling Engine Fan
« Reply #30 on: January 14, 2022, 05:00:31 PM »
I think we all have blown a drill spot once or twice...in my case, even when using a DRO... :embarassed:

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #31 on: January 16, 2022, 12:58:17 AM »
As drawn on the plans, the Power Cylinder, which consists of a round finned body and a rectangular base, is made from a solid piece of brass. Give the current high price of brass, I've opted to make the base separately from the cylinder body and press/solder the two together.

The cylinder starts with a piece of 1” round brass. One end was turned to the OD of the eventual fins, and the steady rest was set-up on that surface. Then a short 0.75” spigot was turned for locating the base, which will have a matching center hole. The spigot is shorter than the thickness of the base, so that when the two are joined there will be a 0.75” x 0.060” well at the bottom for an o-ring. I also started the cylinder bore, but didn't finish it just in case there is any distortion after soldering.


As you can see, I also cut in the first few fins from what will be the bottom. It just seemed a little easier to get them in now before the base is on and spinning around. Once the base is on I'll finish the bore, then move the steady out of the way, put in the large center, and finish the fins.


Here's one shot of the base in process. The top surface has been fly-cut and the center bore has already been brought out to just under the diameter of the cylinder spigot using the boring head. Now the sides are being brought to dimension. Then the fastener holes will be located and drilled.

Regards,
Ron

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #32 on: January 17, 2022, 12:34:14 AM »
Continuing the narrative from yesterday.

With the base finished, I removed the chuck from the lathe with the cylinder still set-up in it, and brought the whole thing over to the bench. The base went on with a fairly light press, so I added a bit of solder for good measure. This all would have been a good time to take a picture – I meant to take a picture – I didn't take a picture.

But I did take a picture of the assembly back on the lathe, ready to clean up the bottom of the base and finish the bore out to 0.6”


Then the rest of the fins were cut in and the cylinder was parted off.




Bottom view showing the 0-ring.


And where it will live next to the displacer cylinder.

Regards,
Ron

Offline Don1966

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Re: Howell Stirling Engine Fan
« Reply #33 on: January 17, 2022, 05:19:41 AM »
Nice job on the cylinders Ron ….. :ThumbsUp:


 :cheers:
Don

Offline Dave Otto

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Re: Howell Stirling Engine Fan
« Reply #34 on: January 17, 2022, 03:57:25 PM »
Parts are looking very nice Ron!

Dave

Offline bent

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Re: Howell Stirling Engine Fan
« Reply #35 on: January 17, 2022, 06:19:05 PM »
Looking good!  :popcorn:

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #36 on: January 17, 2022, 11:49:57 PM »
Don, Dave, and Bent - Thanks a lot guys!

Did routine maintenance on Frau Blau ('67 VW) today, so now work on the fan.
Regards,
Ron

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #37 on: January 20, 2022, 01:21:07 AM »
I decided to tackle one piece of unfinished business on the dispacer cylinder. That is, the port that communicates between the displacer and the power cylinders. This is a pair of drilled holes, as can be seen in the image below, just above “Side View”. You may notice that there is no mention of the angle at which the longer hole is to be drilled.


I picked off an angle of 13 deg., plus noted that a 3/16” rod should just clear one inside edge and one outside edge of the displacer cylinder bore. So that's what I set up. The tilting angle plate is set to 13deg., the part is slid up tight to that, and clamped in the vise. A piece of drill rod gives a check. I also added a C-clamp to hold the part snug to the angle plate, but left it off for the photo.


I started by making a small flat with a 3/16” end mill, then a dimple with a center drill, both of which were only just long enough. Then I carefully drilled through. These kinds of jobs are always a bit nerve wracking, but it turned out just fine.




With that out of the way, I turned my attention to the crankshaft, starting with the pair of crank discs, which also serve as flywheels. I used some 12L14 steel for these. Here the second one is about to be parted off.


And the crank pin hole was then located and drilled on the mill.

Regards,
Ron

Online Kim

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Re: Howell Stirling Engine Fan
« Reply #38 on: January 20, 2022, 02:15:08 AM »
Nice job on the little angled passage - those things are always a little scary to do!

Kim

Offline bent

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Re: Howell Stirling Engine Fan
« Reply #39 on: January 20, 2022, 04:42:07 PM »
 :ThumbsUp: :popcorn:

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #40 on: January 22, 2022, 01:56:21 AM »
Thanks Kim and Bent!

Here are a few shots showing the current state of play. The crankshaft was mostly a straightforward turning and drilling/reaming job, with usual care taken for good fits and concentricity. Assembly is with the help of loctite. I think more time was spent getting the ball bearings to slide onto the drill rod shafts than anything else!




Next I began working on the Crank Arm, which connects to the power cylinder piston. Starting with an oversize block of ali on the mill, I located and drilled/reamed the hole for the crankshaft, and drilled/tapped for the crankpin. Then I shaved it down to thickness.


Much of the shaping I will do on the lathe, so I have it screwed through the shaft hole into a brass fixture held in a collet. The head of the SHCS have been turned to a bit under 0.25” so that I can turn a short little 0.25” boss in that location. But this is pretty much as far as I got today.
Regards,
Ron

Offline Admiral_dk

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Re: Howell Stirling Engine Fan
« Reply #41 on: January 22, 2022, 11:03:34 AM »
Great family shot and finish   :ThumbsUp:

Still following  :popcorn:   :cheers:

Per

Offline Bear

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Re: Howell Stirling Engine Fan
« Reply #42 on: January 22, 2022, 04:31:29 PM »
Ron, you sure do know how to optimize working with the Taig lathe and mill. That is coming along beautifully.

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #43 on: January 22, 2022, 08:27:13 PM »
Thank you, Per!

Quote
Ron, you sure do know how to optimize working with the Taig lathe and mill.
Thank you, Bear. I don't know that I know much, but I do enjoy trying and learning.
Regards,
Ron

Online RReid

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Re: Howell Stirling Engine Fan
« Reply #44 on: January 23, 2022, 12:59:25 AM »
Picking up where I left off on the crank arm. Here you can start to see the general shape emerging.


And here is the part at the conclusion of the “lathe phase”.


Next, it's back onto the mill to cut in the taper from hub to crank pin.


And a couple more filing buttons were turned for rounding off the crank pin end. The little nipple at the right hand end fits into the threaded hole for alignment. The hub end was filed  more or less free hand, with some sorta-close scraps in place to give guidance.


All finished. These close-up shots never fail to reveal a few spots that still need attention!



Regards,
Ron