Author Topic: Strictly.... “ Hot Air “  (Read 71654 times)

Online Chipmaster

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Re: Strictly.... “ Hot Air “
« Reply #225 on: October 07, 2018, 01:06:42 PM »
Did some fettling and rough machining on my new platform casting for the Alyn Foundry Robinson Hot Air engine yesterday. Graham / Alyn Foundry brought it over a couple of weeks ago, its one of a new batch by the Barr & Grosvenor Foundry in Wolverhampton UK. You can see by the photographs so far so good - no cold shuts or blow holes but chilled around the edges.

Perhaps anyone else machining one of these castings might check how the lettering 'Robinson Patent' on the end of the casting lines up before they start. On my casting the lettering on the end lined up perfectly with the top which was why I mounted the casting upside down on parallels and milled the round flange first. I milled about 0.080" off before it was machined all over the surface.

When I turned the casting over to mill the top it was flat all over and only needed about 0.015" off to clean up the entire surface. I wish I could avoid the swirl machine marks left by my cutter, I guess they could be a symptom of a worn seventy plus year old milling machine so I might use my shaping machine to finish the top of the casting.

Andy
« Last Edit: October 08, 2018, 07:54:55 AM by Chipmaster »

Offline Jasonb

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Re: Strictly.... “ Hot Air “
« Reply #226 on: October 07, 2018, 01:16:21 PM »
Looking good.

I wonder if any more are cast in the future if the foundry are able to anneal the castings, I can't see it would add that much to the final cost and could just be done on the ones with thing sections rather than say a chunky flywheel. It is not so much of an issue when flattening the surfaces where carbide tooling can be used but if you need to start drilling or tapping near a hard spot it will soon throw things off or blunt tool.

Online Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #227 on: October 07, 2018, 02:20:26 PM »
Many thanks for the update Andy.

I haven't had a chance to get into the workshop recently however I'll try one in the Le Blonde soon.

I wonder if those edges are showing because of a " speed " issue? Obviously using the lathe and a single point cut at lower speed might see something different ?

Regarding a " planed " finish, yes that would certainly make the engine look more authentic as most Robinson engines were done that way originally.

Jason, those castings were fairly expensive to make. Adding a cost for annealing them might prove too much for a potential customer to bear. If my sample shows similar signs of hardness having been machined in a different fashion then we might have to consider that option.

Cheers Graham.

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Re: Strictly.... “ Hot Air “
« Reply #228 on: October 07, 2018, 07:32:03 PM »
Hello All.

I finally got out there....

Mounted in my large 4 Jaw chuck the photo shows the top half ( cold end ) of the displacer cavity bored to size and the displacer piston rod hole also bored and lapped to 8 mm diameter.

No sign of any " chill " on the mounting flange.

It'll be a chuck change tomorrow, back to the 3 Jaw for facing the top.

Cheers Graham.

Offline Ian S C

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Re: Strictly.... “ Hot Air “
« Reply #229 on: October 08, 2018, 12:27:52 PM »
For those without a shaper you could probably draw file some parts.
Ian S C

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Re: Strictly.... “ Hot Air “
« Reply #230 on: October 08, 2018, 07:39:57 PM »
Indeed, Ian.

And this casting machined like Butter!

Using the lathe I found little if any " hard " spots and a single pass produced the attached.

Hmmm, perhaps yet another engine to come?

Cheers Graham.

Offline Jo

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Re: Strictly.... “ Hot Air “
« Reply #231 on: October 08, 2018, 07:48:11 PM »
I wonder if that will fit in Big C's four jaw or I need to get the little faceplate out  :thinking:.

Jo
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Re: Strictly.... “ Hot Air “
« Reply #232 on: October 08, 2018, 08:02:10 PM »
I wonder if that will fit in Big C's four jaw or I need to get the little faceplate out  :thinking:.

Jo

Well Jo, if I knew who or what " Big C " was I might be able to help.

My Le Blonde has a 7 and a half inch swing the platform passes  comfortably over the saddle arms. The whole job can be done in under an hour and that's including the change of chucks.

Cheers Graham.

Offline Jasonb

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Re: Strictly.... “ Hot Air “
« Reply #233 on: October 08, 2018, 08:55:22 PM »
Should not be a problem getting it in your chuck, would even fit mine as it is gripping the inside of the recess, however it may only turn through 270degrees on mine before there is a loud bang as it hits the bed.  :-[

Or do you think the faceplate will be needed to keep it withing the masters gap?

Offline Jo

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Re: Strictly.... “ Hot Air “
« Reply #234 on: October 09, 2018, 01:24:14 AM »
I wonder if that will fit in Big C's four jaw or I need to get the little faceplate out  :thinking:.

Jo

Well Jo, if I knew who or what " Big C " was I might be able to help.

Big C is my Colchester Master which has a 6 1/2" swing across the bed without taking the gap out. Little C is my Cowells ME lathe :D

Should not be a problem getting it in your chuck, would even fit mine as it is gripping the inside of the recess, however it may only turn through 270degrees on mine before there is a loud bang as it hits the bed.  :-[

Or do you think the faceplate will be needed to keep it within the masters gap?

I was rather thinking I might need to use the face plate with the top surface bolted against it to turn the underside of the casting as Big C only has a 10" 4 jaw chuck. The three jaw will easily hold the bottom once it is turned but the shape of the casting might be close even over her bed  :thinking:

Jo
« Last Edit: October 09, 2018, 08:10:23 AM by Jo »
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Offline Jasonb

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Re: Strictly.... “ Hot Air “
« Reply #235 on: October 09, 2018, 08:07:42 AM »
Quote
Big C is my Colchester Master which has a 5 1/2" swing

I thought your master was bigger than that, even my Warco can swing 11" :thinking: You seem to have lost 2" of swing somewhere as most are 6.5" ctr height or is it the imperial sizes confusing you :LittleDevil:

I suppose if you can have the jaws at 45degrees around the round part of the top rather than one gripping the end with the letters you stand more chance of getting it in the 4-jaw

Offline Jo

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Re: Strictly.... “ Hot Air “
« Reply #236 on: October 09, 2018, 08:10:58 AM »
Yes corrected the size.
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Online Chipmaster

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Re: Strictly.... “ Hot Air “
« Reply #237 on: October 09, 2018, 11:21:53 AM »
Here's a picture of the Robinson HA Platform casting attached to the faceplate of my Colchester Chipmaster.
The Chipmaster has a 5.1/2" swing over the bed which the casting misses by about 1/4"  :).

Andy

Offline Jo

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Re: Strictly.... “ Hot Air “
« Reply #238 on: October 09, 2018, 12:04:31 PM »
Thanks Andy so it should be Easy-peesy then  :)

JB must have one of those special undersized 5 1/2" lathes  :-X

Jo
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Offline Jasonb

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Re: Strictly.... “ Hot Air “
« Reply #239 on: October 09, 2018, 12:29:57 PM »
No mine is oversize as 280mm equates to 11.023" :LittleDevil:

 

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