Author Topic: Strictly.... Hot Air  (Read 58633 times)

Online Twizseven

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Re: Strictly.... Hot Air
« Reply #495 on: January 16, 2021, 07:37:24 PM »
Oak base finished and support for ceramic burner turned out of a piece of brass and then all assembled (just need three brass screws to mount it but shop had just shut).

Tried the no.3 jet but did not appear to be getting any gas, so switched to the no.5 jet.  Once warmed up turned the gas as low as could get then left the engine running on the bench whilst I did other stuff.

By tea time I thought I had better switch it off.  It had run without any issues for five and a quarter hours (5 1/4hrs).  The water level had dropped a bit but that was all.

Will try the no.3 again tomorrow.

Overall very pleased with it. :cartwheel:


Colin
« Last Edit: January 16, 2021, 08:36:39 PM by Twizseven »

Offline ettingtonliam

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Re: Strictly.... Hot Air
« Reply #496 on: January 21, 2021, 12:33:19 PM »
There is a 1" dia. bore in the cylinder casting, and the brass disc forming the governor valve is also shown as 1" dia. Is the disc supposed to be an easy fit in the bore, say, 31/32" dia, or is it supposed to fit against the end face of the 1" bore, say, 1 1/16" dia?
Is it recommended to drill a couple of bleed holes in the disc to prevent the engine from coming to a complete halt when the valve closes?

Offline Alyn Foundry

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Re: Strictly.... Hot Air
« Reply #497 on: January 21, 2021, 01:10:42 PM »
There is a 1" dia. bore in the cylinder casting, and the brass disc forming the governor valve is also shown as 1" dia. Is the disc supposed to be an easy fit in the bore, say, 31/32" dia, or is it supposed to fit against the end face of the 1" bore, say, 1 1/16" dia?
Is it recommended to drill a couple of bleed holes in the disc to prevent the engine from coming to a complete halt when the valve closes?

Hi Richard.

There are small discrepancies in the drawing, make the disc just slightly oversized to the hole so that when it's drawn close it seals the opening.

Two 1/8" holes drilled through the disc will stop the engine grinding to an abrupt halt.

Cheers Graham.

Offline Jasonb

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Re: Strictly.... Hot Air
« Reply #498 on: January 21, 2021, 01:24:37 PM »
this help

Offline ettingtonliam

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Re: Strictly.... Hot Air
« Reply #499 on: January 21, 2021, 01:30:14 PM »
Thanks gents, just what I wanted to know!

Offline ettingtonliam

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Re: Strictly.... Hot Air
« Reply #500 on: January 25, 2021, 01:34:57 PM »
I presume that the diffuser rod has some sort of crosshead block at the top, to take the pin at the bottom of the links. My 1991 drawing doesn't show anything. I'm thinking of a bronze block reamed 3/16" for the pin, and threaded onto the end of the rod.
What has anyone else done?

Online Twizseven

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Re: Strictly.... Hot Air
« Reply #501 on: January 25, 2021, 01:42:58 PM »
Liam,

I just drilled and reamed the diffuser rod for the pin which passes through the links.

Colin

Offline Alyn Foundry

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Re: Strictly.... Hot Air
« Reply #502 on: January 25, 2021, 01:51:28 PM »
Hi Richard.

There's nothing " fancy " about this engine....

The 5/16" or 8 mm displacer rod has nothing more than the 3/16" diameter hole cross drilled and reamed to pick up on the bottom link pin. I always used to use a small centre drill to create an oil way and cup in the end to keep the pin lubricated.

Cheers Graham.

Offline Jasonb

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Re: Strictly.... Hot Air
« Reply #503 on: January 25, 2021, 03:09:17 PM »
I went with the fancy option of a square block drilled and tapped for the rod, cross reamed hole and rounded over end

Offline Alyn Foundry

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Re: Strictly.... Hot Air
« Reply #504 on: January 25, 2021, 04:44:59 PM »
The originals weren't that fancy Jason. But it obviously works.

Here's a picture of the various " fancy " bits from Gardner archives.

Cheers Graham.

Offline ettingtonliam

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Re: Strictly.... Hot Air
« Reply #505 on: January 25, 2021, 05:36:56 PM »
I don't really like the idea of a 5/16" dia cross drilled rod floating around in the 15/32" gap between the links, or the steel rod working on a steel pin . I know the amount of running its likely to do is minimal, but yes, what Jason did is what I have in mind.

Offline ettingtonliam

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Re: Strictly.... Hot Air
« Reply #506 on: February 08, 2021, 01:40:13 PM »
The full size engine was the Robinson No.4 wasn't it? Given the minimal power output of hot air engines, what sort of purposes were they intended to serve? I like my engines to have something to drive, so now my engine is approaching completion, I need to think of a suitable 'load' even if only for display purposes.

Were there Robinson No.s 1,2 and 3, and were they even smaller?

Was there a Robinson colour for their engines?

Offline Alyn Foundry

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Re: Strictly.... Hot Air
« Reply #507 on: February 08, 2021, 02:36:00 PM »
Hi Richard.

Yes, a Number 4. This, I believe was Gardner's size system. Your engine is a half scale replica of a Gardner built size 4 with " squat " base designed to be run on a gas ring. I believe they made a tall base too.

The number 6, Gardner's largest, weighed in at nearly half a Ton and developed half a horse power.

The smaller engines were ideally suited to light loads like sewing machines and Dentist drills. A small Coffee grinder might look rather nice too.

Attached picture is of 3 different sizes made to Robinson's design but by other manufacturers.

Cheers Graham.

Oops, forgot the colour question. I've seen many originals over the years mostly painted either Red or Green.
« Last Edit: February 08, 2021, 02:39:38 PM by Alyn Foundry »

Offline ettingtonliam

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Re: Strictly.... Hot Air
« Reply #508 on: February 08, 2021, 02:54:56 PM »
Hmm
A half size working sewing machine is probably beyond me, though small ones do come up on ebay from time to time, at a price. A half size Victorian dentists drill doesn't appeal somehow.
Given that there was the Robinson 'chippie' gas engine, presumably for driving the spud peeler, I suppose theres no reason why a hot air engine couldn't do the same thing. Now, do we have any pictures of a suitable spud peeler?
I grow potatoes, so I wouldn't be short of ones to experiment with.

Offline Alyn Foundry

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Re: Strictly.... Hot Air
« Reply #509 on: February 08, 2021, 03:17:30 PM »
The " ensemble " as seen at Beamish.

The engine in the picture is the full size type " X " that I scaled down in 1998/9.

Cheers Graham.