Brent Van Arsdell Limited Edition restoration

Discussion on Stirling or "hot air" engines (all types)
Tom Booth
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Re: Brent Van Arsdell Limited Edition restoration

Post by Tom Booth »

Yes, I know of, and have used sodium silicate (water glass) before.

Here is a video demonstrating the new fire resistant magnesium compared with normal magnesium.


https://youtu.be/4iHSDjH3kBc


Somehow, I'm not too overly concerned about either one in a little LTD engine.

Magnesium is also rather inert if there is no oxygen. Maybe something to keep in mind for a pressurized engine.

But another thing I might just try with this engine as well is to do away with the displacer altogether and use a diaphragm, possibly with a fixed, stationary regenerator, as described in another thread.

viewtopic.php?f=1&t=2690


Which I see just now you left some comments on. You mention the regenerator with the star shaped holes, but the fixed regenerator with diaphragm was further down on the page, so not sure if you saw that concept drawing.

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That has not been tested in a pancake type engine but I'm fairly certain it would work, though probably wouldn't look so great for this particular engine.

The engine though, is surprisingly easy to assemble and disassemble so I may end up using it for a lot of experimenting.

If I can get the OK, I might even make arrangements to reproduce the engine to offer for sale and make in my workshop once I get that going.

Good point regarding the regenerator experiment BTW. The control engine did not have the ports in the displacer. A potential "hidden variable", less air resistance.

I'm rather skeptical that regenerators are actually useful. Probably not if an engine is actually converting heat into work output very efficiently.

Also the engine with the regenerator did not run for quite as long. It ran faster, but also quit running sooner. During operation the top of the engine with the regenerator also felt a bit warm. The engine with the displacer remained cool to the touch, so, the engine with the regenerator seemed to be letting more heat pass through faster. Not at all what I was expecting.
Alphax

Re: Brent Van Arsdell Limited Edition restoration

Post by Alphax »

I don't know if you have seen this, but it seems to be a similar idea of putting wire regenerator into a foam displacer.

Interestingly he reports a similar outcome to yours (your star-shaped regenerator inserts) - he says that his engine speeded up as well:-

https://www.youtube.com/watch?v=yeKXfF6gR-s
Tom Booth
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Re: Brent Van Arsdell Limited Edition restoration

Post by Tom Booth »

Alphax wrote: Sat Feb 19, 2022 10:43 am I don't know if you have seen this, but it seems to be a similar idea of putting wire regenerator into a foam displacer.

Interestingly he reports a similar outcome to yours (your star-shaped regenerator inserts) - he says that his engine speeded up as well:-

https://www.youtube.com/watch?v=yeKXfF6gR-s
That's one of the things (that video, among others) that inspired me to do the experiment.

Actually there were other experiments using round holes, but it was difficult to keep the steel wool in place without extra weight. The star shaped was just intended as a way to keep the steel wool in place.
Tom Booth
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Re: Brent Van Arsdell Limited Edition restoration

Post by Tom Booth »

Having been recently notified that the mica I intend using for the displacer has been shipped, and may arrive sometime before next month, I may be getting back to this restoration project soon.

As the plan is to make this engine much more heat resistant, cutting a ring from a glass canister for the displacer chamber walls, and ditching the plastic; I thought, as long as glass is being used, I recently happened across some videos on glass engraving. It might be nice to add a decorative touch of some sort.


https://youtu.be/DEWzIJGUjfQ

Haven't really settled on any particular pattern or design, and I have actually never engraved glass before, but it is something to think about.
Tom Booth
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Re: Brent Van Arsdell Limited Edition restoration

Post by Tom Booth »

The workshop is some distance away from being fully set up, but given a work bench, drill press, and grinder, and some extension cords, I managed to get started and cut a stainless steel "cookie cutter" from the rim of one of my canisters of appropriate size.
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The yellow Styrofoam thing in the flower pot base, in case it isn't obvious, is the old displacer from the restoration engine. The plastic ring around it is the old misshapen displacer chamber, both of which I wish to replace.

I've got the silicon carbide, the flower pot, a displacer size cookie cutter, some ceramic fiber blanket, water glass (somewhere around), I think everything needed for the microwave kiln, some fusible stained glass, baking soda, kiln paper etc. To make some, hopefully, attractive foamed glass
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And I've also got some bottle cutters, to cut out the glass ring for the new displacer chamber, but don't really have any glass engraving tools yet, but that's no reason not to go ahead and make it, undecorated for now, when I get the chance.

It would probably also be a good idea to get a dedicated microwave to use in the shop for these kind of projects and keep the one in the kitchen for actual food.
Tom Booth
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Re: Brent Van Arsdell Limited Edition restoration

Post by Tom Booth »

I just got back from the post office to sign for a package, not knowing what it was.

Turns out it was a little brass lamp I had sent for a while back.

When I purchased the Arsdell engine, the little burner was missing, Or possibly it was never supplied with one. So I've been searching for a replacement.

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I thought that this little lamp might work because from the illustrations on eBay, or wherever, it looked like the little brass burner on the bottom could be separated from the rest of the lamp.

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As it turns out, I was right about that.

The lamp goes quite well with the engine. Unfortunately it is just a little too big to fit under the engine between the support posts properly.

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Nice little brass lamp though. All the pieces can be unbolted so it comes apart. The burner, glass, heat riser etc. So not a total loss. Maybe I can still figure out some way of making it work.
MikeB
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Re: Brent Van Arsdell Limited Edition restoration

Post by MikeB »

May I suggest cutting a larger disc for the base, then those supports can still be used, but twisted at an angle to match?
Tom Booth
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Re: Brent Van Arsdell Limited Edition restoration

Post by Tom Booth »

MikeB wrote: Tue Jun 07, 2022 7:53 am May I suggest cutting a larger disc for the base, then those supports can still be used, but twisted at an angle to match?
Not entirely sure what you mean. Something like that would probably work, but I just got another little brass lamp in the mail today. It fits in the space, and even looks quite a lot like the lamp illustrated in the drawing.

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The little chimney, (which is actually a handle, the wick is normally on the side) might be a little too tall.

I will probably drill out the point on the top for the wick and cut it down a bit if necessary. It would also work well enough as is.
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