Model Engine Maker

Engines => From Plans => Topic started by: RReid on December 28, 2021, 12:52:59 AM

Title: Howell Stirling Engine Fan
Post by: RReid on December 28, 2021, 12:52:59 AM
For my next project I've decided to build Jerry Howell's “Super Stirling Engine Fan”. I first learned about Stirling engines many years ago when we used one in an engineering school thermodynamics lab on measuring engine efficiency. I thought it'd be interesting to build one then but I had no tools, no money, no time, and not enough knowledge. Now I have at least some of those things. Unlike my other engines, this one can even serve a practical purpose! Here's a photo from the website (http://www.model-engine-plans.com).
(https://i.postimg.cc/3rjVMdcv/S-Fan.jpg)

Work actually commenced before Christmas with the “displacer head”. This was a fairly straightforward milling task. Not having any ball end mills, I used a 1/8” router bit to round off the bottoms of the two wide intersecting channels.
(https://i.postimg.cc/cCsHstrh/IMG-1677.jpg)

(https://i.postimg.cc/rsQpzy4k/IMG-1681.jpg)

With that done, and a few days of family time, I moved on today to the “displacer cylinder”. That's the larger, silvery bit with all the fins in the stock photo. The first step was to cut a rough, approximate sized block from a disc of 1.5” aluminum I have.
(https://i.postimg.cc/hjPZ8rKb/IMG-1684.jpg)

A flycutter was used to square up two edges. Even though the cuts were kept light, the C-clamp added a bit of extra comfort on the second, hangy-outy edge shown here.
(https://i.postimg.cc/vBqq0VBR/IMG-1686.jpg)

(https://i.postimg.cc/prm04Lhm/IMG-1688.jpg)

Then the rest of the lines were laid out and rough cut on the bandsaw.
(https://i.postimg.cc/yx2fHCcv/IMG-1690.jpg)

(https://i.postimg.cc/WpyYrgCg/IMG-1691.jpg)

At this point I moved the piece over to the lathe to begin boring the cylinder, starting with a few drills from 3/16” up to 1/2”.
(https://i.postimg.cc/ncQR1Mf5/IMG-1692.jpg)

In a few days I'll continue with a boring bar to get to the final 0.940” diameter.
Title: Re: Howell Stirling Engine Fan
Post by: Jasonb on December 28, 2021, 10:17:52 AM
Off to a good start. I have been toying with the idea of doing a Raab or Jost engine, possibly as a fan which they mostly made or just as a stand alone engine.
Title: Re: Howell Stirling Engine Fan
Post by: Flyboy Jim on December 28, 2021, 02:14:16 PM
Good start and writeup.  :ThumbsUp:

I'll be following along on your project.

Jim
Title: Re: Howell Stirling Engine Fan
Post by: RReid on December 29, 2021, 03:20:50 AM
Thanks Jason. I looked up Raab and Jost, can definitely see the heritage behind the one I'm doing. They have more Victorian finery though!

Thank you, Jim. Happy to have you along!
Title: Re: Howell Stirling Engine Fan
Post by: Bear on December 29, 2021, 03:50:36 PM
Pleased to see a Stirling build. Will be watching closely. Been contemplating making one; but have been deterred by comments I have read about the precision required to make them run. Maybe this thread will give me the courage to give it a go.
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 01, 2022, 03:29:24 AM
Got the bore of the displacer cylinder finished. On to the the next step; finishing the surfaces to size and cutting the fins.
(https://i.postimg.cc/tJhQ2Ltq/IMG-1694.jpg)

(https://i.postimg.cc/RZv9bVDj/IMG-1695.jpg)

With the displacer head resting in place.
(https://i.postimg.cc/fTcDK0Bc/IMG-1697.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 03, 2022, 01:28:33 AM
Since the last post, I've used the flycutter to bring all the sides of the displacer cylinder body to size, with the exception of the L-shaped side, where the flycutter couldn't get into the corner. For that I used a 1/2” end mill to get both faces cleaned up in one set-up. That short leg of the L forms the base for the power cylinder.
(https://i.postimg.cc/05c8qJXL/IMG-1698.jpg)

Next I moved back over to the lathe for cutting the fins (or more precisely, the slots between the fins). But first I re-purposed one of the fixture pieces left over from the Radial Five build by mounting it on an arbor held in a collet and re-cutting the spigot to fit the cylinder bore. This piece can be seen sitting on the cross slide.
(https://i.postimg.cc/5Nyf9NZj/IMG-1702.jpg)

That way I could use my heavy fixed center to support to work for cutting the fins. These require fairly deep plunge cuts, and the cuts are interrupted for over 60% of the way. I'm glad it's aluminum (or aluminium) rather than steel!
(https://i.postimg.cc/Ghfd4nCK/IMG-1705.jpg)

Got the first 9 roughed in by end of day. The slot width per plans is 0.093”. I've cut them using my 0.0625” cut-off tool. I plan to go back over them with a 0.093” tool, but I'll have to grind one up first. I'll need it to get the last slot or two up against the L cut as well, as the holder for the other tool won't let me snuggle up in there.
(https://i.postimg.cc/cL8ZYk1S/IMG-1707.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Kim on January 03, 2022, 05:27:43 AM
Nice work on the fins, Ron!

I always found using the cutoff tool on the Taig a little harrowing.  It could be done, but it was slow and scary.  That's one thing I don't miss about a little lathe...  I agree - good that it was aluminum and not steel!  :o

Kim
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 03, 2022, 04:00:53 PM
Thanks Kim!

I daydream sometimes about a bigger lathe (I miss the 13" LeBlond I had at one time), but with the space I have available it's just not an option right now. Making the little lathe do bigger work does add to the challenge, which I try to view as adding to the fun! That (relatively) large fixed center really does help a lot. And my youthful work in the deep well drilling machine shop included taking ~1/4+" deep interrupted cuts on cast steel up to 24" OD, which rather inured me to the noise and vibration. At least with this job I don't have hot blue chips flying everywhere!

I do like my lathe, but if Taig would make one that was just a bit bigger and heavier, more on par with the milling machine (which is excellent), and with thread cutting capability, then I might be seriously tempted.
Title: Re: Howell Stirling Engine Fan
Post by: bent on January 03, 2022, 09:40:09 PM
That looks fun, will be watching along, Ron! :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 05, 2022, 12:37:37 AM
This morning I got a new 0.093” parting tool ground up that cuts virtually flush on one side so I could finish the last two fin slots up against that “L” leg, as well as go back through the other ones turning the fat fins into skinny ones.
(https://i.postimg.cc/J4PLn6Q3/IMG-1708.jpg)

I'm not sure if this two-stage process was really worth the extra effort or not, but now it's done. Apart from drilling mounting holes for the power cylinder, which I won't do until that part is made so I can match drill them, and some cleaning up of machine marks etc., that completes the displacer cylinder. The power cylinder will be brass, is smaller, round, and has fewer and shallower fins, so will be a bit easier. It does have a rectangular base, but I plan to do make that separately and silver solder the two together. But first I need to order some brass, cuz I don't have any around that's quite big enough for either part!
(https://i.postimg.cc/Vkvcbq7x/IMG-1710.jpg)

(https://i.postimg.cc/qvFHcNSz/IMG-1713.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Minh Thanh on January 05, 2022, 11:34:53 AM
Look Great !
Title: Re: Howell Stirling Engine Fan
Post by: Kim on January 05, 2022, 03:21:56 PM
That's a lot of nice skinny looking cooling fins!  And done on a Taig no less - lot of work went into that!  :popcorn:

Kim
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 05, 2022, 03:26:13 PM
Thank you,  Minh! Thank you, Kim.
Also Bear and Bent - glad to have you along!
Title: Re: Howell Stirling Engine Fan
Post by: Bear on January 05, 2022, 03:42:56 PM
Thanks, Ron. Pleased to be along. That is some pretty fantastic work  :ThumbsUp:.
Title: Re: Howell Stirling Engine Fan
Post by: bent 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
Title: Re: Howell Stirling Engine Fan
Post by: crueby 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!
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
(https://i.postimg.cc/zDRGDD11/IMG-1714.jpg)

(https://i.postimg.cc/pXbXmN25/IMG-1717.jpg)

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.
(https://i.postimg.cc/nc4V7dzR/IMG-1721.jpg)

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.
(https://i.postimg.cc/7ZXxtfSS/IMG-1724.jpg)

(https://i.postimg.cc/bvJq7pRW/IMG-1726.jpg)

(https://i.postimg.cc/6QmBwgj3/IMG-1731.jpg)

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.
(https://i.postimg.cc/C1nSK7X4/IMG-1732.jpg)

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.
(https://i.postimg.cc/PJGhvZkn/IMG-1736.jpg)

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).
(https://i.postimg.cc/ZY3Jtfrb/IMG-1739.jpg)

And the finished connecting rod.
(https://i.postimg.cc/9FhCWGpG/IMG-1742.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Bear on January 11, 2022, 12:32:36 AM
 :ThumbsUp:
Title: Re: Howell Stirling Engine Fan
Post by: Kim on January 11, 2022, 05:43:14 AM
Great work, Ron!
Lots of work goes into that part, doesn't it?!

Kim
Title: Re: Howell Stirling Engine Fan
Post by: Flyboy Jim on January 11, 2022, 02:01:24 PM
That's a great looking part Ron. Thanks for taking us on the journey.

Jim
Title: Re: Howell Stirling Engine Fan
Post by: bent 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:
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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...
Title: Re: Howell Stirling Engine Fan
Post by: Art K 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
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
(https://i.postimg.cc/9FwbwHNJ/IMG-1747.jpg)

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!
(https://i.postimg.cc/0ygfpXTx/IMG-1749.jpg)

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.
(https://i.postimg.cc/13pKMcSF/IMG-1751.jpg)

And another set of filing buttons (I found this pair ready for use in the junk drawer) to round off the end.
(https://i.postimg.cc/hGc1Yz45/IMG-1754.jpg)

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.
(https://i.postimg.cc/63QL9kvV/IMG-1760.jpg)

(https://i.postimg.cc/bJF0dmx7/IMG-1762.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: crueby on January 14, 2022, 02:09:47 AM
Quick thinking qnd a nice save!


 :popcorn: :popcorn: :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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:
Title: Re: Howell Stirling Engine Fan
Post by: Bear on January 14, 2022, 04:16:39 PM
Coming along very nicely.
Title: Re: Howell Stirling Engine Fan
Post by: bent 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:
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
(https://i.postimg.cc/qqyp1jx7/IMG-1764.jpg)

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.
(https://i.postimg.cc/05w55y1q/IMG-1765.jpg)

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.
(https://i.postimg.cc/jdYxDYRn/IMG-1768.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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”
(https://i.postimg.cc/8z4Wd9Zm/IMG-1769.jpg)

Then the rest of the fins were cut in and the cylinder was parted off.
(https://i.postimg.cc/BvwKkD98/IMG-1772.jpg)

(https://i.postimg.cc/632vX3tM/IMG-1773.jpg)

Bottom view showing the 0-ring.
(https://i.postimg.cc/zBsRXrf8/IMG-1774.jpg)

And where it will live next to the displacer cylinder.
(https://i.postimg.cc/yx03DbJ9/IMG-1776.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Don1966 on January 17, 2022, 05:19:41 AM
Nice job on the cylinders Ron ….. :ThumbsUp:


 :cheers:
Don
Title: Re: Howell Stirling Engine Fan
Post by: Dave Otto on January 17, 2022, 03:57:25 PM
Parts are looking very nice Ron!

Dave
Title: Re: Howell Stirling Engine Fan
Post by: bent on January 17, 2022, 06:19:05 PM
Looking good!  :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
(https://i.postimg.cc/d1t3XgWg/IMG-1777.jpg)

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.
(https://i.postimg.cc/NFKMGmv4/IMG-1779.jpg)

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.
(https://i.postimg.cc/qqW7Nqkd/IMG-1780.jpg)

(https://i.postimg.cc/WpyzWW0f/IMG-1781.jpg)

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.
(https://i.postimg.cc/9FqMvdpX/IMG-1784.jpg)

And the crank pin hole was then located and drilled on the mill.
(https://i.postimg.cc/Gpbm8Z19/IMG-1788.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Kim 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
Title: Re: Howell Stirling Engine Fan
Post by: bent on January 20, 2022, 04:42:07 PM
 :ThumbsUp: :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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!
(https://i.postimg.cc/8Cg4G8wd/IMG-1795.jpg)

(https://i.postimg.cc/639h7dky/IMG-1797.jpg)

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.
(https://i.postimg.cc/x8ZGFBcz/IMG-1799.jpg)

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.
(https://i.postimg.cc/66bh34Yp/IMG-1800.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Admiral_dk on January 22, 2022, 11:03:34 AM
Great family shot and finish   :ThumbsUp:

Still following  :popcorn:   :cheers:

Per
Title: Re: Howell Stirling Engine Fan
Post by: Bear 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.
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
Title: Re: Howell Stirling Engine Fan
Post by: RReid 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.
(https://i.postimg.cc/t4v2HMGN/IMG-1802.jpg)

And here is the part at the conclusion of the “lathe phase”.
(https://i.postimg.cc/1XKr7WK6/IMG-1804.jpg)

Next, it's back onto the mill to cut in the taper from hub to crank pin.
(https://i.postimg.cc/T1xc98nf/IMG-1808.jpg)

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.
(https://i.postimg.cc/0N6Z508R/IMG-1810.jpg)

All finished. These close-up shots never fail to reveal a few spots that still need attention!
(https://i.postimg.cc/vmph4xB1/IMG-1812.jpg)

(https://i.postimg.cc/pTzZzVhs/IMG-1813.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 24, 2022, 12:24:00 AM
It made sense to work on the Fan Hub next, as it goes onto the opposite end of the crankshaft from the crank arm finished yesterday. It is mostly a turning job, with some drilling and slots cut in to hold the fan blades. I'll wait until I have the blades made to actually cut those slots.

The hub started as a piece of 1.125” aluminum, which gets turned first to 1.1”. Then the end that will be towards the crank is turned further, to 0.625” and a short little spigot just like the crank arm got is added. This bears up against the ball bearing. Finally a blind hole is drilled and reamed to 0.1875” to fit the crankshaft.
(https://i.postimg.cc/3xhkY4zJ/IMG-1814.jpg)

With that end done the part is turned around. Since it will now be chucked on the already turned surface I use some bits of brass over the jaws to protect the finish. This end also gets turned down to 0.625”. Then the end is to be rounded off.
(https://i.postimg.cc/RZTNFCz1/IMG-1816.jpg)

I have a Taig radius tool that they sent me by mistake some time back, so I was thinking this would be a perfect chance to use it. But I forgot that, by it's design, it needs at least 1.5” of part hanging out beyond the chuck or the tool won't clear. So I started thinking of cutting stair step segments and finishing those off with a file. Then I remembered Jo's recent post in which she used a corner rounding router bit is a similar situation. Eureka!

Worked a treat. Thanks Jo!
(https://i.postimg.cc/d0tDTMqb/IMG-1824.jpg)

(https://i.postimg.cc/TP71Vk1p/IMG-1826.jpg)

(https://i.postimg.cc/6383Yd4z/IMG-1827.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Kim on January 24, 2022, 01:18:07 AM
Nice work on the fan hub, Ron!  :popcorn: :popcorn:

And great use of the router bit trick!

Kim
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 24, 2022, 03:06:03 PM
Thanks Kim! I love picking up tricks like that, and the great folks on MEM are a prime source.
Title: Re: Howell Stirling Engine Fan
Post by: bent on January 24, 2022, 06:49:09 PM
Nice hub, love that use (again) of a router bit for a large radius cutter.  :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 24, 2022, 08:49:40 PM
Thank you, Bent!

And now, here's a tale of a close call. The bore of the fan hub turned out to be a bit tight for the drill rod used in the crankshaft. Other pieces of drill rod of the same size fit fine, but of course not the one that matters! So I was massaging the hole and checking it with a piece of rod from the same mother stock as the crankshaft. It was going well and I had a good fit down to about 2/3 the length of the bore, when the sample rod grabbed. I was holding and turning it by hand in a dismounted drill chuck, not meaning to force things, but guess I tried just a bit too hard and it grabbed and grabbed hard. Then nothing I tried, including the use of a heat gun on the hub, could loosen it, partly because it was difficult to hold either piece very securely or bring much force to bear.

In the end, I chucked it back up on the lathe, clocking it in as perfectly as I could (I got it to where the needle of the indicator was just barely moving). Then I cut off  the protruding rod and drilled through the 0.1875” remainder with a #14 (0.1820”) drill. Luckily this worked well, and most of the offending rod came out as a partial shell without harming the original bore.
(https://i.postimg.cc/Vk2L5DTQ/IMG-1833.jpg)

(https://i.postimg.cc/G2CLx9dX/IMG-1838.jpg)

Then I was able to run an old, short, and reliable 3/16” drill in to open it up just that tiny bit needed, and clean up the marks I had made on the face and chamfer in the earlier attempts. Crisis resolved and now it fits fine and without any wobble. Whew!
(https://i.postimg.cc/mDybXRrB/IMG-1837.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: crueby on January 24, 2022, 08:54:14 PM
Close call! If you were making a movie it would have been a nice suspense building scene...


 :popcorn: :popcorn: :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 24, 2022, 09:08:34 PM
Stay tuned for Alfred Hitchcock's "The Model Engineer".
Title: Re: Howell Stirling Engine Fan
Post by: crueby on January 24, 2022, 09:14:37 PM
Stay tuned for Alfred Hitchcock's "The Model Engineer".
I'm peering over the back of the couch. With popcorn ready!
Title: Re: Howell Stirling Engine Fan
Post by: Kim on January 24, 2022, 09:43:48 PM
Yes, sounds like some tense moments!  But you came through with a good save!  :ThumbsUp:

Well done, Ron,
Kim
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 25, 2022, 03:23:15 AM
Thanks Kim. I try not to get too stressed about these things; they happen and it wouldn't have been a difficult part to remake. But still, I was pretty relieved and happy that I didn't have to!

And Chris -  :lolb:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 27, 2022, 02:59:36 AM
Work has been proceeding on what is called the Hot Cap. This is the part that transfers the heat of an alcohol flame into the displacer cylinder, while limiting heat loss to the surrounding structure. It is preferably made of stainless steel.

On one of our trips to visit our son in TX, I was given several rods of stainless, 2 of 1” diameter and one of 3/4”. These are of unknown alloy, but are non-magnetic, so likely 300 series. As a test, I cut a piece off, chucked it in the lathe, and tried turning it to the smaller diameter specified in the plans for the hot cap. It machined pretty easily, so is probably 303, maybe 304. That made me happy, since I once had to machine some 316 SS with a small and tired Jet lathe, and it was an unholy chore, even using the old braze-on carbide tooling I still had in my toolbox.

Anyway, since the material choice was a go, I proceeded over to the mill to cut the called for crenellations in the top.
(https://i.postimg.cc/RFCSzNC4/IMG-1844.jpg)

Then back to the lathe to create the 1.55” deep by 0.94” bore, which leaves a rather thin wall in a 0.965” OD! I got it out to 0.43125” with drills.
(https://i.postimg.cc/XJ2VN4XF/IMG-1845.jpg)

Then the rest of the way with a boring bar. That boring bar, by the way, came from the same source as the SS rod. In the picture the bore is almost, but not quite, done. Regardless of the grade of SS, with no power feed this was a tiresome bit of work.
(https://i.postimg.cc/j2LRLmJ1/IMG-1847.jpg)

There is still a mounting flange make and attach. The plans show the part as a single piece, but ,as with the power cylinder, I am opting to make the flange separately. I will modify a SS washer to fit for the purpose.
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 27, 2022, 10:36:24 PM
No work in the shop today. We took a drive over to the coast instead. An absolutely gorgeous mid-winter day.
(https://i.postimg.cc/1RLK1CQK/IMG-1848.jpg)

(https://i.postimg.cc/m2CyLYZW/IMG-1854.jpg)

(https://i.postimg.cc/Dwhd8SmJ/IMG-1855.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Flyboy Jim on January 28, 2022, 06:29:11 PM
No work in the shop today. We took a drive over to the coast instead. An absolutely gorgeous mid-winter day.

Looks like a day well spent.

Jim
Title: Re: Howell Stirling Engine Fan
Post by: Dave Otto on January 28, 2022, 08:47:40 PM
Beautiful photos Ron!

Dave
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 29, 2022, 12:22:24 AM
Jim and Dave – Thanks guys! It really was a nice day. Now back to SERIOUS business.  :)

To make the base for the hot cap I started with a 7/8” SS washer. This had an ID just a bit smaller than the finish size needed, and an OD quite a bit larger. I re-used a fixture made for the Radial Five build that screws to the face plate. A small adjustment to the center spigot was all that was needed to center the washer and fasten it through the central threaded hole. This allowed me to turn the OD from about 2” down to 1.5”.
(https://i.postimg.cc/yxs11Mvb/IMG-1862.jpg)

Next the fixture was transferred to the mill for drilling and tapping of the 4-40 mounting holes.
(https://i.postimg.cc/SNQSwpXX/IMG-1864.jpg)

Then back to the lathe. With the washer held on place by the mounting screws and the central fixture screw removed I could bore the ID for a press fit onto the hot cap.
(https://i.postimg.cc/MH5Wv9LK/IMG-1868.jpg)

To minimize the stress on the thin wall of the hot cap, I heated the washer in the toaster oven (medium toast) before pressing them together. Worked out great. That base isn't going anywhere.
(https://i.postimg.cc/BZBZYvv9/IMG-1870.jpg)

(https://i.postimg.cc/m2dL46Mm/IMG-1869.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 31, 2022, 12:47:40 AM
I've been getting a few of the small bits knocked out. The first was the Displacer Rod Bushing, which is made of Delrin and guides the displacer rod through the head.
(https://i.postimg.cc/HWZr41vb/IMG-1878.jpg)

That was a more or less trivial turning job, Delrin is sooo easy to work. But unlike metals, a drill bit tends to produce a slightly under-, rather over-size hole in it. But I found that even a crudely filed piece of brass rod makes a perfectly adequate D-bit reamer for getting a nice running fit in this stuff.
(https://i.postimg.cc/Gt2HwXtB/IMG-1876.jpg)

Also of Delrin is the Small End for the power piston rod. I continued to experiment with the soft material by doing most of the rounding off with a razor blade, finishing with a flat needle file and some wet/dry paper. The result is not perfect but OK; it will be lost down inside the piston anyway.
(https://i.postimg.cc/Z530SBbL/IMG-1880.jpg)

(https://i.postimg.cc/5tVyN4jW/IMG-1882.jpg)

Lastly but not leastly I worked on the Big End. Back to aluminum for that. It still needs rounding off, but I don't think I'll use a razor blade on this one. And yes, the actual piston rod will be somewhat longer than this one.
(https://i.postimg.cc/WzhbftYg/IMG-1890.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Admiral_dk on January 31, 2022, 11:42:57 AM
Great looking parts and description  :cheers:

When you mentioned the undersized holes, I thought of a Reamer - so great to se that such a simple D-Bit did the trick  :ThumbsUp:

Per
Title: Re: Howell Stirling Engine Fan
Post by: RReid on January 31, 2022, 05:42:38 PM
Thank you, Per.

I do like to try to find the simplest solution first. I neglected to mention the relevant fact that the brass rod was about 0.001" larger than any of my drill rod.
Title: Re: Howell Stirling Engine Fan
Post by: bent on February 01, 2022, 06:00:06 PM
Lovely work, Ron.

 :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 02, 2022, 01:12:46 AM
Thank you, Bent.

Next I turned my attention to the Top Ring, which is part of the legs/stand assembly. The “works” get attached to the top of it, with the hot cap hanging down through, while the legs get attached at the bottom, to hold it all up above the alcohol burner resting on the base.

The ring was gotten out of a piece of 2.75” diameter stock. Since that won't clear the lathe top slide, I had to do “reach around turning” until it would. This time, rather than using a right cutting turning tool at the front, I tried using my 0.0938” cut-off tool at the back, which worked well.
(https://i.postimg.cc/s2FPn1qS/IMG-1894.jpg)

I was able to finish the OD turning conventionally, face a bore the recess for that side, and part it off. Then turn it around to face and bore the other side, ending up with this.
(https://i.postimg.cc/hG9LNcRY/IMG-1896.jpg)

These two images show how the hot cap fits into the top ring.
(https://i.postimg.cc/nzp4JgHh/IMG-1898.jpg)

(https://i.postimg.cc/Kzfnvfzr/IMG-1900.jpg)

The hot cap already has the mounting holes drilled into its flange, so it serves as the “master” for drilling both the displacer cylinder and the top ring. To ensure the displacer cylinder and the hot cap were perfectly lined up for drilling, I turned the little plug fixture shown, with one diameter to fit the hot cap and another to fit the cylinder. With everything clamped together, I spotted, drilled, and tapped each hole in turn. Laborious, but reliable.
(https://i.postimg.cc/SRtCcKcn/IMG-1903.jpg)

(https://i.postimg.cc/NF0RyX2h/IMG-1901.jpg)

Drilling the top ring was a little simpler, since it only needed clearance holes and the fit of the hot cap flange into the recess takes care of alignment. I still need to drill the angled holes for the legs and the set screws that clamp the legs, as well as some fastening holes for the heat shield.
(https://i.postimg.cc/rFKSMSLx/IMG-1909.jpg)

It's getting taller!
(https://i.postimg.cc/nVdvy3Nn/IMG-1905.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 07, 2022, 12:52:31 AM
Since the last post I've been getting some of the odds and ends done, like match drilling and tapping some of the mating parts so they can now get mounted. I also have gotten the legs pretty much sorted out.

Here the top ring is being set-up for drilling the angled holes for the legs.
(https://i.postimg.cc/sxLprXYm/IMG-1910.jpg)

And another set of holes for the set screws. I could just get those done with a jobber length drill without fouling the chuck on the part.
(https://i.postimg.cc/DfpQsC9G/IMG-1911.jpg)

The plans show a 5” diameter ring of aluminum as the base. The alcohol lamp sits inside the ring, and the perimeter is drilled to accept the legs. That's fine, except the Taig can't swing 5” without a riser block, which I don't have. I do have a scrapyard casting of 4 1/2” diameter, which I could swing, but probably wouldn't have to as I could use it mostly as is. But I did want to flycut the surface to clean it up. And that's were the problem showed up. I expected fairly soft with lots of nasty black dust. Instead I got fairly hard with silver chips, and finally a really hard spot that I couldn't get through with HSS.
(https://i.postimg.cc/MKc7Y7wF/IMG-1913.jpg)

Thinking about it later I also realized that resting the lamp on the surface of the base instead of inside an open ring could be a hazard. If the fan got knocked over, the lamp would go with it, probably spilling burning alcohol in the process. Time for a new plan. I decide to forgo the one piece base and make individual “feet” for the legs instead. I made a prototype from the same stainless steel I got the hot cap out of. That looked great, especially since the legs are also stainless, but another problem arose.
(https://i.postimg.cc/BnH2rJX5/IMG-1917.jpg)

That 1” SS bar I have turns and drills with no problem, but parting it off is another story. I got horrible screeching chatter every time I went near it with either of my cut-off tools. I had the same thing with the hot cap, but not quite as bad, and was able to power through it wearing ear plugs. For these, my personal cost/benefit analysis didn't argue for proceeding, and I opted to make the set of aluminum instead.

Once again, a router bit was pressed into service as a form tool.
(https://i.postimg.cc/Hxs58533/IMG-1920.jpg)

And the tops get drilled at angle to match the angle of the legs.
 (https://i.postimg.cc/7L4SDj2F/IMG-1919.jpg)

Maybe not quite as nice as SS, but not far off.
(https://i.postimg.cc/T1BWssxH/IMG-1926.jpg)

So here's the current state. Won't be much shop time this week, as we have some grandparenting duties to perform. Not exactly a hardship.
(https://i.postimg.cc/Gt4yqCWy/IMG-1925.jpg)

(https://i.postimg.cc/d1HC21xF/IMG-1924.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Minh Thanh on February 07, 2022, 01:09:18 AM
Very beautiful !!
 :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: Howell Stirling Engine Fan
Post by: Kim on February 07, 2022, 05:46:25 AM
That's looking really sharp, Ron!  :ThumbsUp: :popcorn:
Kim
Title: Re: Howell Stirling Engine Fan
Post by: wagnmkr on February 07, 2022, 12:14:59 PM
This looks lovely!
Title: Re: Howell Stirling Engine Fan
Post by: propforward on February 07, 2022, 02:03:31 PM
Looking great - truly delightful! Also, thank you for showing your set ups, I am always very grateful to see those details as I often learn something.
Title: Re: Howell Stirling Engine Fan
Post by: bent on February 07, 2022, 06:13:27 PM
Nice work! :popcorn:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 07, 2022, 09:46:07 PM
Thanks for all the compliments and feedback, guys! It's very much appreciated.  :cheers:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 08, 2022, 12:06:06 AM
I must admit that, in its current state without any fan blades yet, this is what it make me think of :
(https://i.postimg.cc/DwvVpz18/IMG_1927.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Craig DeShong on February 08, 2022, 07:51:24 AM
Looks good Ron, can’t wait for the next installment, though I understand grand-parenting also has it’s own rewards.
Title: Re: Howell Stirling Engine Fan
Post by: wagnmkr on February 08, 2022, 11:53:34 AM
I thought that it looked like an instrument that NASA might have left on the moon or Mars. The fan blade will make a difference.
Title: Re: Howell Stirling Engine Fan
Post by: Bear on February 08, 2022, 03:37:21 PM
Impressive, Ron.
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 08, 2022, 06:58:30 PM
Hello Craig, Wagnmkr, and Bear, and Thanks!
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 15, 2022, 12:55:01 AM
Getting back to work on the fan, today's task was to make the Displacer Top. The Displacer Body, which will be made next, is basically an open ended can. This part closes off that open end, and a pressed in rod connects from it to the displacer crank con rod. The assembly is essentially a piston. The name of the game for both parts is low mass and thin walls.

The most interesting part of making the displacer top was the bore back, or recess, in it's “upper” end. I used a very small grooving tool I had ground for another task some time ago to work this in. The side “walls” when finished are about 0.035” -0.040” thick, the end wall 0.050”.
(https://i.postimg.cc/XqbpGpy5/IMG-1930.jpg)

(https://i.postimg.cc/RhLqc4cD/IMG-1935.jpg)

With that done, the job was parted off. Then I turned it around and mounted the small end in a 1/4” collet to face to length and drill a clearance hole part way in from that side.
(https://i.postimg.cc/9FcDcw25/IMG-1940.jpg)

The finished part.
(https://i.postimg.cc/rFgKsyyd/IMG-1941.jpg)

(https://i.postimg.cc/wjv3mK3w/IMG-1942.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Roger B on February 15, 2022, 08:10:33 PM
Looking good  :ThumbsUp:  :ThumbsUp:  :wine1:  I have a delta Stirling underway in the background awaiting some suitable stainless steel tubing  ::) 10m no problem 10cm no chance  :toilet_claw:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 17, 2022, 12:43:32 AM
Thanks Roger! Good luck finding the tubing you need, I'll be interested in the build. :cheers:

The Displacer Body started with a piece of 1” OD aluminum. A skim cut was taken to give a nice surface for the steady. It will get turned down further later.
(https://i.postimg.cc/kX4WFdLw/IMG-1946.jpg)

It needed to be bored to just under 3” deep, which is a stretch for my biggest boring bar. The second set screw is just barely catching, so I added a C-clamp for reinforcement.
(https://i.postimg.cc/0NgmsKjH/IMG-1947.jpg)

That went fine, no problems, but it took awhile, starting from a 7/16” drilled hole. Here's the finished 0.865”  bore, with the the displacer top sitting on the ways.
(https://i.postimg.cc/FHkc8VrL/IMG-1949.jpg)

Next it's time to finish turning the OD down to 0.895”, leaving a wall thickness of 0.015”. To do this I removed the steady and supported the end with my high end, custom made bull-nose live center. This consists of a bit of scrap with a 1/4” hole through the middle and a bevel on one end, a 1/4” shank center drill/countersink mounted in the drill chuck as an arbor, a copper thrust washer, and a liberal application of Red & Tacky grease. Did the job required perfectly well.
(https://i.postimg.cc/W3TkDRMG/IMG-1951.jpg)

And I ended up with one 3” tall aluminum can. Make a few more and they could be used for 6-packs of  Turnenfuuwl Machinist's Grog. Or not.
(https://i.postimg.cc/SNvCgvh4/IMG-1954.jpg)

(https://i.postimg.cc/k5xSXMtM/IMG-1956.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Bear on February 17, 2022, 03:52:33 PM
That is very impressive how you were able to bore that out. I would be intimidated to try that.
Title: Re: Howell Stirling Engine Fan
Post by: bent on February 17, 2022, 05:49:55 PM
The intimidating thing for me would be parting it off - how close to the end of the bore am I? 
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 17, 2022, 08:37:05 PM
Quote
That is very impressive how you were able to bore that out. I would be intimidated to try that.
Thanks Bear, but it really wasn't bad at all. More a matter of patience than anything. Rather than intimidate I do hope my posts sometimes show what can be done with fairly modest tools and using found or scrap materials or whatever is “at hand” to get the job done, and done safely.

Quote
The intimidating thing for me would be parting it off - how close to the end of the bore am I? 
Thanks Bent. I'll admit to sweating that, but I had to trust my measurements were correct, and they were (whew!). Oh, and at 0.050" the end wall is more than 3x thicker than the side walls, giving some breathing room.
Title: Re: Howell Stirling Engine Fan
Post by: Bear on February 17, 2022, 10:16:36 PM
Thanks, Ron. The intimidation is due to my inexperience, and not your post. The intimidating factor was how I would get the inside bored concentrically with such a long tool for such a long distance. Maybe "intimidation" was a poor word choice on my part.
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 18, 2022, 01:27:32 AM
All good, Bear!  :ThumbsUp:

I think the last major part to machine is the Power Piston. I've been putting this off till last because it's made of graphite. Not that machining graphite is difficult, it's not at all. But it makes even more nasty black dust than cast iron. This I know from experience, so I've been dreading it a little. At least in this case the part is small. But still, a good day to NOT oil the ways before starting work, it's easier keep the machine clean that way. The other reason for delaying was the brittleness of graphite. It doesn't take much to knock a chunk off, either while working or while it's sitting around waiting to be assembled.

Mr. Howell recommended using an ordinary piece of paper to bring the piston OD to final size. Here I have some note paper wrapped around a brass bar to give a flat surface. Worked really well to get to a Goldilocks fit.
 (https://i.postimg.cc/zGQfmqjz/IMG-1961.jpg)

(https://i.postimg.cc/N0rjBZJ1/IMG-1962.jpg)

The next task is to drill and bore a stepped cavity into the piston to accept the con rod, per typical piston practice (PTPP). Might as well be boring into a black hole, so some extra lighting was desired. I stuck a little magnetic puck light onto the first thing that came to hand that was heavy enough to not fall over and small enough to put where I wanted it.
(https://i.postimg.cc/rm1ytxLs/IMG-1965.jpg)

The other thing that is PTPP is opening that cavity into a slot so that the con rod can swing. So the chuck was moved to the mill for that job, and also to drill the wrist pin hole. I figured if I set it up on the tilting angle plate, I'd be able to rotate the work 90 degrees to drill the hole while only having to locate it in one axis.
(https://i.postimg.cc/D07vQ02g/IMG-1966.jpg)

That would have worked well if I'd remembered that the slot would have to be milled using the Y-axis, not the X-axis, in order for the wrist pin to be perpendicular to it, not parallel. Dang!
(https://i.postimg.cc/1XM9vSXZ/IMG-1968.jpg)

The solution was to slightly loosen the threaded nipple the chuck mounts to so the chuck could be rotated, lining it up with the help of a bar in the slot and a square, and lightly clamping so the chuck can't turn. Not much force involved in drilling a 1/16” hole in graphite, so I felt OK with this and it kept my positioning in the Y-axis intact.
(https://i.postimg.cc/J7Q4rNqd/IMG-1970.jpg)

(https://i.postimg.cc/X77Npr1N/IMG-1972.jpg)

After going back to the lathe to be parted off, the piston was done. Then I gave the machines a good cleaning and oiling.
(https://i.postimg.cc/65jWRBFr/IMG-1973.jpg)

And with still some time and energy left, I made a start on the fan blades.
(https://i.postimg.cc/sgMV4tRt/IMG-1975.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: bent on February 18, 2022, 06:13:42 PM
 :popcorn: :ThumbsUp:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 19, 2022, 12:28:17 AM
Kind of a piddly fiddly day today, but I did get the four fan blade blanks cut out and trimmed to size. I also started and ran the Upshur, just to give it a bit of exercise after sitting on the shelf a few weeks. Started pretty easily and ran happily, which made me happy.
(https://i.postimg.cc/k5CJ9YnT/IMG-1983.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 21, 2022, 12:19:25 AM
I made the fan hub a while back in the build, but put off slotting it for the blades until I actually had the blades. Since I made those the other day, it's now time to finish the hub.

The set-up is: 1/32” slitting saw in the mill, tilting angle plate set to 32 degrees, the dividing head mounted to that to provide the indexing, and the hub mounted to a 3/16” piece of drill rod held in the DH with a collet. I actually did a small test piece first, making a few cuts to proof the set-up and make sure all was copacetic before starting on the real hub.
(https://i.postimg.cc/htBf2SnM/IMG-1987.jpg)

(https://i.postimg.cc/7YgLGpzz/IMG-1989.jpg)

Because these slots are to be 0.3” deep, and that means quite a few passes with that small toothed slitting saw, I scribed three lines 0.1” apart on a piece of scrap from cutting out the blades. This served well as a depth gauge that I used to check myself and ensure that I hadn't lost count along the way (who, me?).
(https://i.postimg.cc/cHrHvC71/IMG-1988.jpg)

(https://i.postimg.cc/Qdhdp0gy/IMG-1991.jpg)

Here's the hub after the last of the four slots was completed.
(https://i.postimg.cc/L5jmP1JS/IMG_1994.jpg)

And the first trial fitting of the blades. I'm going to leave it set up on the angle plate and DH because that's a good way to hold it for the final operation. After attaching the blades first with loctite, each is locked in place with a 1/16” hole drilled through the hub and blade and a roll pin inserted. But before I do that I need to polish those blades a bit.
(https://i.postimg.cc/Y2FrZJbP/IMG-1997.jpg)

(https://i.postimg.cc/tCHqj2c4/IMG-1998.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Admiral_dk on February 21, 2022, 11:04:20 AM
Great setup and result - you can't be far from first run  :ThumbsUp:

Per
Title: Re: Howell Stirling Engine Fan
Post by: Dave Otto on February 21, 2022, 07:06:49 PM
Looking good Ron!
Nice work on the blade assembly.

Dave
Title: Re: Howell Stirling Engine Fan
Post by: Craig DeShong on February 21, 2022, 10:37:03 PM
Your stirling fan is really coming together.  I’m really enjoying this build.
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 22, 2022, 12:20:01 AM
Thank you, Per. A few small jobs still left to do, but yes, it won't be long now.
Dave and Craig, Thank you very much!

This morning I assembled the fan blades onto the hub using green loctite and set it aside to cure till tomorrow. Then I turned to making the Flame Guard. This is a pleasant hand fab job in thin brass sheet.
 “Chisels and hammers and files – Oh My!” (Dorothy, in a lost version of Wizard of Oz)
(https://i.postimg.cc/Twqc0kcc/IMG-1999.jpg)

After annealing it was rolled around a piece of 1.5” aluminum rod and held with a hose clamp to set the diameter. Half was left hanging out beyond the bar so I could silver solder it. Then I turned it around to solder the other half.
(https://i.postimg.cc/RhSLDcsx/IMG-2000.jpg)

Almost finished. The mounting tabs will get trimmed shorter, but they are used to screw it to the bottom of the Top Ring, so as to shield the lamp flame and the the lower part of the Hot Cap from drafts.
(https://i.postimg.cc/6qMfJyg2/IMG-2002.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: fumopuc on February 22, 2022, 06:54:10 AM
Hi Ron, I do love this fabrication work.
Title: Re: Howell Stirling Engine Fan
Post by: Kim on February 22, 2022, 03:23:28 PM
Wow, Ron - you are almost done with this sterling engine!  Can't wait to see it all up and running. I'm enjoying following your progress on this.  :popcorn:
Kim
Title: Re: Howell Stirling Engine Fan
Post by: Dan Rowe on February 22, 2022, 03:50:18 PM
Hi Ron, I have been following this from the start and it is a fun build.

“Chisels and hammers and files – Oh My!” (Dorothy, in a lost version of Wizard of Oz)

That should have been sung by the Tin Man according to the test audience.

Cheers Dan


Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 22, 2022, 07:27:46 PM
Achim, Kim, and Dan - Thank you!
Quote
That should have been sung by the Tin Man according to the test audience.
The test audience has a good point!  :Lol:
Title: Re: Howell Stirling Engine Fan
Post by: bent on February 22, 2022, 10:15:26 PM
Still following along... :popcorn: :ThumbsUp:
Title: Re: Howell Stirling Engine Fan
Post by: Don1966 on February 23, 2022, 05:33:42 AM
 :Love:


 :cheers:
Don
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 25, 2022, 02:15:30 AM
Thanks Bent; Thanks Don!

Almost there.
(https://i.postimg.cc/44wcs9Wb/IMG-2006.jpg)

(https://i.postimg.cc/L6X1X87d/IMG-2007.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: Admiral_dk on February 25, 2022, 11:17:13 AM
Matches the rest on the table very nicely (and that includes the heat source)  :praise2:

So what is missing besides "lighting the Fuse" ?

Per
Title: Re: Howell Stirling Engine Fan
Post by: bent on February 25, 2022, 06:51:38 PM
Looks nice!  Like Per said, when are you going to fire it up?  :popcorn: :ThumbsUp:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 25, 2022, 08:33:47 PM
Thank you, Per!
Quote
So what is missing besides "lighting the Fuse" ?
Not much really. Attaching the flame guard and the usual final fiddling & fettling.

Quote
Looks nice! Like Per said, when are you going to fire it up?
Thank you, Bent! Already have. First run video is below. That horrible knocking is exaggerated in the video, but it is there. Seems the displacer is just contacting the bottom of the cylinder. Once I correct that I'll post another video.
kO1Osx9DQgE
Title: Re: Howell Stirling Engine Fan
Post by: Kim on February 25, 2022, 08:40:13 PM
Wow!  Congratulations, Ron! That runs really well!   :ThumbsUp: :popcorn:

Are you going t make a blade guard for the fan, or just leave it OSHA unapproved?  :Lol:

Kim
Title: Re: Howell Stirling Engine Fan
Post by: crueby on February 25, 2022, 11:11:01 PM
Aside from the trapped shop elf knocking to get out out of the cylinder, its running great!!   :ThumbsUp:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 25, 2022, 11:45:48 PM
Quote
Are you going t make a blade guard for the fan, or just leave it OSHA unapproved?
Thanks Kim! I'm going to go ahead and live dangerously, at least for now.   ;D
Quote
Aside from the trapped shop elf knocking to get out out of the cylinder, its running great!!
Thanks Chris! Runs even better now that I let the elf out!  :LittleDevil:

I find I have to turn the volume on my computer down to at least 40% to make the video sound as quiet as real life. Anyway, I'm pretty happy with it. It's been a fun build, and I appreciate all the support and encouragement along the way. Thank you!
bzZxzwN3_ro
Title: Re: Howell Stirling Engine Fan
Post by: Bear on February 26, 2022, 12:49:09 AM
 :ThumbsUp: :ThumbsUp: Great job.
Title: Re: Howell Stirling Engine Fan
Post by: Admiral_dk on February 26, 2022, 01:55:09 PM
Really great runner (now you leth the Elf out  ;) )  :praise2:

It looks like it's running fast, so - is it moving a lot of air ?

Per
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 26, 2022, 04:05:34 PM
Thanks Bear!

Quote
It looks like it's running fast, so - is it moving a lot of air ?
Hi Per. Well, it's not going to knock the hat off your head, but it does make a nice little breeze.
Title: Re: Howell Stirling Engine Fan
Post by: Dave Otto on February 26, 2022, 07:27:27 PM
Congrats on a runner Ron!
It looks great!

Dave
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 27, 2022, 12:49:53 AM
Thank you, Dave!
Title: Re: Howell Stirling Engine Fan
Post by: propforward on February 27, 2022, 12:52:45 AM
That’s great! What a fun build.
Title: Re: Howell Stirling Engine Fan
Post by: fumopuc on February 27, 2022, 08:50:03 AM
Hi Ron, very nice and useful runner. Congratulations.

Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 27, 2022, 04:27:38 PM
Hi Stuart. Hi Achim. Thank you both!
Title: Re: Howell Stirling Engine Fan
Post by: Don1966 on February 27, 2022, 07:42:31 PM
Very nice job and a awesome runner….. :Love:



 :drinking-41:
Don
Title: Re: Howell Stirling Engine Fan
Post by: RReid on February 28, 2022, 12:10:53 AM
Thank you, Don!

This is an image I meant to post earlier and never did. A view of the inner works "undressed", so to speak.
(https://i.postimg.cc/HkwxYKGW/IMG-2012.jpg)
Title: Re: Howell Stirling Engine Fan
Post by: bent on February 28, 2022, 11:29:48 PM
Woo hoo!  Looks and runs great, nice job! :ThumbsUp: :DrinkPint:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on March 01, 2022, 12:35:16 AM
Thank you, Bent!  :cheers:
Title: Re: Howell Stirling Engine Fan
Post by: Craig DeShong on March 01, 2022, 12:59:42 AM
Well done; :ThumbsUp:

 I have visions of me trying to balance the fan blades by shaving a bit of the heavy blade, over and over, till only the axle would be left.  :wallbang:   Obviously, you didn’t have that problem. :cheers:
Title: Re: Howell Stirling Engine Fan
Post by: RReid on March 01, 2022, 01:13:06 AM
Quote
I have visions of me trying to balance the fan blades by shaving a bit of the heavy blade, over and over, till only the axle would be left.
Hi Craig. Yes, that would have been a small problem. :ROFL:
Actually, I weighed each blade before they were mounted and all were the same to the nearest gram, which is as good as my little scale can do. They all came from one sheet, which probably helps. I used to balance the props for my RC airplanes, but with that result I figured I'd see how things went first. As it turns out, at the speed the thing wants to run there is little to no vibration. I must be living right.
Title: Re: Howell Stirling Engine Fan
Post by: Minh Thanh on April 03, 2022, 04:21:31 PM
That’s great !!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
Thanks for sharing .
Title: Re: Howell Stirling Engine Fan
Post by: RReid on April 10, 2022, 05:35:45 PM
Hello Minh Thanh, and Thank you.

Sometimes, when I show my engines to family or friends, someone asks "so what does it do?" Building this fan was partially in response to that, to build something with a "function". A couple of days ago I put that into practice. It was an unseasonably warm evening, so I had the fan running on the table while we ate dinner. It gave a very nice, soft little breeze, made almost no noise, and took up little table space. Pleasant and unobtrusive.