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Author Topic: Huxtable Hot Air Engine.  (Read 26893 times)

Offline Stilldrillin

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Huxtable Hot Air Engine.
« on: July 13, 2010, 08:21:30 AM »
I don`t usually make engines, but I own and repair quite a few...... My latest engine arrived a few days ago.

Several members have asked questions. I`ll try to answer them......  :thumbup:

This is it....... http://www.olds.com.au/stirling/

A heavy, awkward lump of Australian engineering, compared to the toys I`m used to.....




The little thumbscrew on top locates the cylinder into position. Allowing it to be slid off, to demonstrate the action......




Removing 1 nut at the rear of the crankthrow, allows all the action to be removed......







The only "fault" I have found with it, the little end bearing had too much clearance (for me), and allowed a "tick" when running.

I repaired this by unscrewing the hexagon "gland nut" (no packing), from inside the piston skirt, and bushing the conrod back to the 3.5mm dia of the pin pressed into one of it`s hexagon faces.

David D


« Last Edit: July 13, 2010, 08:23:29 AM by Stilldrillin »
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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #1 on: July 13, 2010, 11:19:40 AM »
And here`s an all action video.......





David D

« Last Edit: July 20, 2012, 06:00:01 PM by Stilldrillin »
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Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Rob.Wilson

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Re: Huxtable Hot Air Engine.
« Reply #2 on: July 13, 2010, 12:36:58 PM »
Cheers for the taking the time to strip the engine and show the workings , David  :thumbup: :thumbup: :thumbup: :clap: :clap: :clap:

Rob
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Offline Bernd

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Re: Huxtable Hot Air Engine.
« Reply #3 on: July 13, 2010, 07:30:09 PM »
Thanks Dave.

That's one smooth running engine.  :thumbup:

Bernd
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Offline Dean W

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Re: Huxtable Hot Air Engine.
« Reply #4 on: July 14, 2010, 01:53:04 AM »
Thanks very much, David!  That tells the story well.
The hot end cap is silver brazed on, is that right?

Dean
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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #5 on: July 14, 2010, 04:08:57 AM »
Quote from: Dean W on July 14, 2010, 01:53:04 AM
Thanks very much, David!  That tells the story well.
The hot end cap is silver brazed on, is that right?

Dean

Dean,

There is a feint silver ring, in the end of the tube......




I guess the tube is plugged, and silver soldered.

David D
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Offline Dean W

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Re: Huxtable Hot Air Engine.
« Reply #6 on: July 14, 2010, 09:38:06 PM »
Thank you again, David.  Now I know its secrets!
It looks like it would be a fun one to build.  

Dean
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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #7 on: August 12, 2010, 01:07:11 PM »
I wasn't going to show this..... But then realised, I had the chance to show the little end's "gland nut".


The ticking noise returned, after some 12 - 15hrs running. So, I decided to fit a ballrace.

Opened the little end to take the 6mm o/d bearing.....




Components. Pin turned down to 3mm, to fit the bearing.....




Loctited. Ready for rebuild......




Back together.....




The little end has no side float. Fitting perfectly between the hexagon's flat, and the inner skirt diameter.


Tomorrow, I'll see how quiet it runs. Again!  ::)

David D
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Offline Dean W

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Re: Huxtable Hot Air Engine.
« Reply #8 on: August 12, 2010, 07:12:41 PM »
That looks like a very sensible and advantageous upgrade, David.  Should stay quiet now!
May even improve performance, though it ran well before, too.

Thanks for the pics.

Dean
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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #9 on: September 10, 2010, 06:01:51 AM »
I did say I'd bought this engine, like all my others. For fiddling with...... Didn't I ?

Now it's well run in, the poorly designed power piston assembly, is being twisted anti clockwise by the weight of the conrod, I guess!  :scratch:

Piston out, this is what happens. It turns 90 dgrs......




So, I made a balance weight from 1/2" bar......




That looks a little healthier......




Discrete too.......




It has stopped making "new piston/ cyl" noises now.  :thumbup:

Need to look at the crank balance. The table oscillates in harmony with it, at 200rpm!  ::)

David D
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Still drilling holes... Sometimes, in the right place!

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Offline Powder Keg

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Re: Huxtable Hot Air Engine.
« Reply #10 on: September 12, 2010, 08:09:19 AM »
That is a great looking little engine!!! Any chance on you making some drawings for it:o) Seeing how you keep tahing it apart:o)
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Wesley P
A Gismo ??? If it has a flywheel or spins and is made with small parts. I'll take one! If it makes noise, moves, or requires frequent oiling and dusting it's a better deal yet. It's especially right if its shiny and bright; but if it's dirty and dull it wont mater at all...

Rob.Wilson

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Re: Huxtable Hot Air Engine.
« Reply #11 on: September 12, 2010, 01:42:45 PM »
Quote from: Powder Keg on September 12, 2010, 08:09:19 AM
That is a great looking little engine!!! Any chance on you making some drawings for it:o) Seeing how you keep tahing it apart:o)


Good idea  :thumbup:


Rob  :D :) :D
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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #12 on: September 13, 2010, 03:56:21 AM »
Wes, Rob,

Drawings?! Ah! Now we have a problem....... I'm a fag packet scribble type of guy, and I don't smoke!  :scratch:

But, I'm sure if anyone really wants to know, we'll sort something!  :thumbup:

Meanwhile, here's another little vid.....





We're going gas fired, shortly.....

David D
« Last Edit: July 20, 2012, 08:52:22 AM by Stilldrillin »
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Still drilling holes... Sometimes, in the right place!

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Offline Dean W

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Re: Huxtable Hot Air Engine.
« Reply #13 on: September 13, 2010, 05:44:17 PM »
It's a fab runner, David.  Really nice!
I like the quiet enthusiasm in your voice, too.

Dean
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Offline Powder Keg

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Re: Huxtable Hot Air Engine.
« Reply #14 on: September 13, 2010, 09:14:16 PM »
Hey!!! Rob and I don't want to hear any excuses.  :poke:
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Wesley P
A Gismo ??? If it has a flywheel or spins and is made with small parts. I'll take one! If it makes noise, moves, or requires frequent oiling and dusting it's a better deal yet. It's especially right if its shiny and bright; but if it's dirty and dull it wont mater at all...

Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #15 on: September 14, 2010, 03:23:31 AM »
Thanks Dean! Quietly enthusiastic, just sums it up nicely......  :thumbup:

Wes.... Ok...... I can do crappycaddy.....  :scratch:

As time and circumstances permit, I'll measure parts, and post here. 

David D
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Still drilling holes... Sometimes, in the right place!

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Offline sbwhart

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Re: Huxtable Hot Air Engine.
« Reply #16 on: September 14, 2010, 03:35:02 AM »
Wow Dave thats runs very very very nice,

As sweat as a nut  :)

Stew
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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #17 on: September 14, 2010, 03:48:13 AM »
Thanks for that Stew!  :thumbup:

I can't believe how it keeps on improving after each small mod.  :)

Most of my toys deteriorate, as soon as I get 'em......  ::)

David D
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Still drilling holes... Sometimes, in the right place!

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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #18 on: October 01, 2010, 04:03:36 AM »
I had a very satisfactory day in the workshop, yesterday. Worked on another mod, to try to improve balance.

The displacer has a balance weight....... But the relatively heavy piston hasn't...... It wags the table from 200 rpm!  ::)

I made a quadrant from 1/4" thick brass. Then drilled & tapped the side of the bob weight 4BA......




Screwed it into place......




And turned it down to crank throw diameter......




Now it looks like this. Balancing the piston.......




Started up. Much smoother, straight away.



Happy top revs now, are 450 to 500.

Any more than this, it starts to jump around.......  Again!




It's never gone over 400 rpm before........ This time it went up to 578rpm!

Almost 50% extra revs, just for improving the balance!  :D

David D
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Offline steamboatmodel

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Re: Huxtable Hot Air Engine.
« Reply #19 on: October 01, 2010, 09:11:16 AM »
Quote from: Powder Keg on September 12, 2010, 08:09:19 AM
That is a great looking little engine!!! Any chance on you making some drawings for it:o) Seeing how you keep tahing it apart:o)
He did say he bought the engine
http://www.olds.com.au/stirling/
Regards,
Gerald.
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Offline Brass_Machine

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Re: Huxtable Hot Air Engine.
« Reply #20 on: October 01, 2010, 09:36:59 AM »
David,

I know you say you normally don't make engines... but after seeing the work that you do... have you thought about it? You would do very well.

Eric
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Offline Stilldrillin

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Re: Huxtable Hot Air Engine.
« Reply #21 on: October 01, 2010, 09:51:20 AM »
Thanks Eric!
I made one, once! At my usual pace. Life and times get in the way, all too often!  ::)

http://madmodder.net/index.php?topic=1705.0

Incidentally, it now runs much better than ever, at 1 year old it fairly whizzes. Must get the strobe on it......  :thumbup:

David D

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Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!
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