Author Topic: Alyn Robinson Hot Air Engine  (Read 4766 times)

Offline corlissbs

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Re: Alyn Robinson Hot Air Engine
« Reply #15 on: August 27, 2021, 04:01:11 PM »
Hi Graham. I am ready to silver solder the copper bottom to my stainless hot cap and build the displacer piston, from a three piece construction. Although I have the proper tuna can, but without the lid, I have decided to build a piston. If my arrangement does not work, I can fall back on the can and the cast iron hot end. Then assembly.

What do you suggest for the holes in the piston top and bottom? What filler material are you going to use in your engine? Thank you.  Brad from Wisconsin, USA

Offline Alyn Foundry

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Re: Alyn Robinson Hot Air Engine
« Reply #16 on: August 27, 2021, 06:13:37 PM »
Hi Brad.

I’ve built into double figures of the Robinson and have made my builds simpler as I’ve progressed.

I use the heavy duty stainless Steel pan scourers these days as they don’t rust away over time. I now just put four  1/2” holes in each end and place them 90 degrees to each other so the air has to twist a little.

Regarding the displacer tin itself, I’ve recently found a tin of Water Chestnuts that may just work, I’ll be able to say for sure in a few days time.

Cheers Graham.

Offline corlissbs

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Re: Alyn Robinson Hot Air Engine
« Reply #17 on: August 30, 2021, 11:34:57 PM »
Graham, I have another question. This one is on the color that the Robinson engine were painted. I have an old article from Model Engineer Magazine that said that Robinson's were a deep blue, with red arms and a black furnace. Is this the color that you believe they were painted? Thanks. Brad Smith

Offline Alyn Foundry

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Re: Alyn Robinson Hot Air Engine
« Reply #18 on: August 31, 2021, 11:58:01 AM »
Good morning Brad.

One thing for certain, all the furnaces on the Robinson’s I’ve seen over the years were definitely Black. As for the deep Blue, I personally haven’t seen an engine in that colour. Most seem to be predominantly dark Red or mid Green.

Thanks for the update over at.  https://www.facebook.com/groups/ALYNFOUNDRYMODELS/

Cheers Graham.
 

Offline Jasonb

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Re: Alyn Robinson Hot Air Engine
« Reply #19 on: August 31, 2021, 01:22:36 PM »
Blue can look quite nice though mine is probably a bit brighter than "Dark Blue"


Offline Alyn Foundry

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Re: Alyn Robinson Hot Air Engine
« Reply #20 on: August 31, 2021, 01:57:45 PM »
Is that “ wee Robbie “ Jason?

I’m of the opinion that the colours chosen by the builder for their models is what they like. For a “ true scale “ replica then using the same colour scheme as the original is more appropriate.

I recently saw an Alyn Gardner with a bright Yellow flywheel, it certainly “ stood out “   :o

Cheers Graham.

Offline Jasonb

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Re: Alyn Robinson Hot Air Engine
« Reply #21 on: August 31, 2021, 02:18:15 PM »
That's the one.

I suppose it also depends on how you want to depict the model from barn find to original supply to blinged up restoration project. I think a lot of these and stationary engines were just given a coat of paint AFTER assembly before being shipped out of the factory but you seldom see models or restored ones painted in that way most will at least have bright fixings and flywheel rims.

Having done the Heinrici in it's worn paint finish I quite fancy the "wiped over with a diesel soaked rag" finish that gives the rust patia a slight gloss, maybe with a hint of original paint just showing through in one or two places. Something like this

« Last Edit: August 31, 2021, 02:22:03 PM by Jasonb »

Offline corlissbs

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Re: Alyn Robinson Hot Air Engine
« Reply #22 on: August 31, 2021, 04:30:50 PM »
We have 2 blue Robinson engines in the US that I have photographed. The large pumping engine has definitely been repainted. This and a machinery grey 4" were at a regional hot air engine meet. The other 4" blue engine is in a private collection. That paint could actually be original. I will ask the owner of the pumping engine if that was the color before he repainted the engine, and report back. It does follow the information in the  Model Engineer article that I have.

Offline corlissbs

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Re: Alyn Robinson Hot Air Engine
« Reply #23 on: August 31, 2021, 05:12:34 PM »
Graham, you are going to get a chuckle out of this, as over engineering, but I put Oilite bushings in the holes of all the bronze linkage arms. It's what happens when one spends his working life in a railway shop.

Offline Alyn Foundry

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Re: Alyn Robinson Hot Air Engine
« Reply #24 on: September 02, 2021, 03:21:04 PM »
Talking of link motion….

I’m ready to make the pivot pins but have noticed that the Draughtsman appears to have left out the head dimensions.
Is it just me? Or after 30 years hasn’t anyone found this omission?

Cheers Graham.

Offline Jo

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Re: Alyn Robinson Hot Air Engine
« Reply #25 on: September 02, 2021, 04:29:14 PM »
 :-X

For the crank I made mine the same diameter as the central curve on the split rod = 12.7mm same on the pivot bolt on the top of the cylinder. On the links I made it to match the bosses (once they had been filed round to match the holes)

Jo
Enjoyment is more important than achievement.

Offline corlissbs

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Re: Alyn Robinson Hot Air Engine
« Reply #26 on: September 02, 2021, 07:54:28 PM »
The drawing makes it pretty obvious that the head diameter should match the boss diameter.  Brad Smith

Offline corlissbs

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Re: Alyn Robinson Hot Air Engine
« Reply #27 on: September 02, 2021, 09:20:50 PM »
I silver soldered the hot cap. the 0.040" copper bottom is recessed to hold the flame longer, as was done on the full sized Robinson engines.

 

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