Author Topic: Strictly.... “ Hot Air “  (Read 71714 times)


Offline ettingtonliam

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Re: Strictly.... “ Hot Air “
« Reply #121 on: March 31, 2018, 03:28:09 AM »
I've done a bit towards the Robinson, by filing up the gunmetal linkage castings and marking out for drilling/reaming. Haven't made my mind up whether to paint them, in which case they are probably good enough now, or polish them, in which case there is more to do.
Having read this and other sections of the site, I'm disappointed that my iron castings don't have Graham's Special Finish. if I sent them back, do you think he'd do it?

The steam guys seem to get pretty worked up about what grade/material to use for O rings used with steam at about 180C. Any advice about O ring material to use on that big one between the 2 halves of the displacer cylinder? For that matter, now asbestos is unobtainable, will a thick piece of Hallite/Klingerite jointing material be OK between the base casting flange and the flange on the lower half of the displacer cylinder?

Richard

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #122 on: March 31, 2018, 11:43:55 AM »
Hi Richard.    ;)

Great to read you've made a start on your engine.

Regarding the " special " coating it would take years of standing in a damp workshop to achieve!

Mathew is here today to " hopefully " finish his engine, the one who's base was moulded by his grandad and I. We're hoping to get 5 half scale Robinson's together working for the Anson Engine museum Easter opening event tomorrow.

I've managed to drill through the section of Iron that was blocking the " air port " and by press fitting a piece of 15 mm Copper water pipe, Tlnned and Lead loaded the breach between the water jacket and port.

The " O " rings I used/use are a special " high temperature " compound and I still have several on stock, please message me.

The drawing shows the " O " ring fully recessed but I changed my mind as I built a few more. I now machine to one eighth depth in each part, platform and hot pot. This allows for a half thickness gap separation to reduce heat transfer, but the " O " ring also accurately registers the two components as well.

I'll post some photos of Mathew's progress later today.

Cheers Graham.
« Last Edit: March 31, 2018, 12:05:37 PM by Alyn Foundry »

Offline ettingtonliam

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Re: Strictly.... “ Hot Air “
« Reply #123 on: March 31, 2018, 11:59:37 AM »
Hi Graham
Thanks for the reply (its Richard, not Ian by the way)

Given the weather I think a couple of days outside would do for the special coating! We used to 'season' castings outside for about 6 months, partially to let the casting stresses ease out, partially because the rust would lift off any casting sand left on. Did mean that when you started machining, it wasn't just black cast iron dust, but a good amount of orange rust flying around. These castings of mine are over 20 years old now so I think they've been well seasoned even without the rust. I shall go over them with a big old file first, then give them a coat of red oxide primer, before starting work on them. The primer helps prevent any oil getting into the surface texture, I always think.

I will PM you about the O ring.

Richard

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #124 on: March 31, 2018, 01:09:59 PM »
Hi Richard.

I agree 100 % about painting, wished I'd done it several times.... I now have a collection of prototypes that won't take paint no matter what's been tried to remove the ingrained oil.

As promised, a photograph of my repair on Mathew's platform, more to come as the afternoon progresses.

Cheers Graham.

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #125 on: March 31, 2018, 05:28:42 PM »
Getting there....

Assembly ready for the alignment stage.

All clamped and ready for drilling the main bearing pedestal and cylinder. As the displacer rod hole is the only thing that can't move the whole setup is aligned around it.

Just a few more holes to be drilled, tapped and clearanced, a run scheduled for a little later this evening.

Cheers Graham.

Offline ettingtonliam

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Re: Strictly.... “ Hot Air “
« Reply #126 on: March 31, 2018, 09:26:09 PM »
Graham
What are the 2 lugs for on the flange of the base casting in the 2nd photo?
What was the difference between the water cooled version and the air cooled one?
Did the full size one have a separate cooling tank, or did it just rely on having the water in the base topped up from time to time?

Richard

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #127 on: April 01, 2018, 07:21:13 PM »
Graham
What are the 2 lugs for on the flange of the base casting in the 2nd photo?
What was the difference between the water cooled version and the air cooled one?
Did the full size one have a separate cooling tank, or did it just rely on having the water in the base topped up from time to time?

Richard

Hi Richard.

Sorry for my late reply, I have just returned from the Anson Engine museum, where a record 5 half scale engines were seen!

The lugs are where, theoretically, the two fixing bolts for the main bearing pedestal would be threaded.

The air cooled version, I assume you're referring to a picture I posted earlier in this thread? That engine was actually built by another company under license and is simply a " heat sink " with ventilation holes.

No, the number 4 uses the the cored space only for cooling. The number 5 had a hopper that doubled as the main bearing support, it was the number 6 that needed a separate cooling tank.

It would seem that as greater power was needed each size had a bigger cooling requirement.

Cheers Graham.

PS.

I just found this....

<a href="https://www.youtube.com/watch?v=e1SwR0SugeA" target="_blank">http://www.youtube.com/watch?v=e1SwR0SugeA</a>

That was me, right at the end removing one of ours from the platform of the " majestic " number 6.
« Last Edit: April 01, 2018, 09:05:12 PM by Alyn Foundry »

Offline ettingtonliam

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Re: Strictly.... “ Hot Air “
« Reply #128 on: April 02, 2018, 06:18:34 PM »
Graham
I think we are talking about 2 different things. The lugs I'm on about are the 2 hinge like lugs on the front of the circular flange at the bottom of the base casting. I can't understand how they would have anything to do with the main bearings, they aren't anywhere hear them or line up with them. I'm puzzled (easily done, I'm told). I've looked at lots of photos on  this sitge and can't see these lugs on any of the other engines.

Richard

Online Jasonb

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Re: Strictly.... “ Hot Air “
« Reply #129 on: April 02, 2018, 06:25:45 PM »
Could be the casting runners that have not been cleaned up yet.

EDIT, just looked back through the thread and it is indeed where the runners fed the iron into the casting as you can see from the patterns.

« Last Edit: April 02, 2018, 06:30:41 PM by Jasonb »

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #130 on: April 02, 2018, 06:51:05 PM »
Hello Richard.

I'm pretty sure Jason's " nailed " it! I thought you were referring to the two small lugs on the top underside.

We never, ever let our castings near anyone with a grinder, quickest way to a scrapper! Instead we made specially shaped runners that could be snapped off from the running system leaving the last bit for the model engineer to " fettle " .

Cheers Graham.

Online Jasonb

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Re: Strictly.... “ Hot Air “
« Reply #131 on: April 02, 2018, 07:10:24 PM »
these bits

Offline ettingtonliam

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Re: Strictly.... “ Hot Air “
« Reply #132 on: April 02, 2018, 07:26:58 PM »
Show how stupid I am!

Offline Admiral_dk

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Re: Strictly.... “ Hot Air “
« Reply #133 on: April 02, 2018, 09:52:36 PM »
Well we are not stupid just because we haven't got a clue about the answer to something and that is why we ask :stickpoke:

It's when you can't learn something that the term gets more appropriate .... though even that definition is fraught, as we know that there are different ways to learn something, and only one or two usually works for one individual and they are most likely not the same ones that work for a different person ....

That said - I do certainly know how it feels to fell stupid  :-[ we all been there.

Best wishes

Per

Offline ettingtonliam

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Re: Strictly.... “ Hot Air “
« Reply #134 on: April 07, 2018, 10:27:24 AM »
Graham
I've tried to message you about the big O ring for the Robinson, but it doesn't seem to work, not for me anyway. How do I get in touch?

Richard

 

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