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Eccentric's "Turnado"

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Neil Wyatt19/07/2018 19:33:45
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I complemented Gary on the choice of colour, and he confided in me that they just came out like that!

It is a lovely example of the patternmaker's/foundryman's art.

Neil

Michael Gilligan19/07/2018 21:45:25
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Posted by Neil Wyatt on 19/07/2018 19:33:45:

I complemented Gary on the choice of colour, and he confided in me that they just came out like that!

.

I have no objection to the colour, but I'm a little bewildered: The toolpost block is said to be made from investment cast Ductile Cast Iron. ... So, why is it not grey ? [glazed by residue from the burnt 'wax' perhaps ?]

MichaelG.

Ian Parkin19/07/2018 22:10:22
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I had never realised that cast iron would come out of the mound looking like this ...die cast yes but not cast iron...I cant imagine what causes the colour

49dedc10-cd75-4b61-9856-4a3d2a658a62.jpeg

Eccentric Engineer20/07/2018 08:34:43
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Hi All

Just thought I'd clear up a slight misunderstanding about the brown colour of the Turnado tool posts.
They don't come from the casting plant like that; after I machine them I send them for a black oxide surface treatment and that's how they come back.
Steel turns jet black in a few minutes but for some reason cast iron only goes a deep brown, and that's only after they leave it in the bath for up to an hour.
I suspect it might be the lack of carbon in the cast iron that causes it but that's only a guess.

I really like the finish, it's almost an oxblood/ aged bronze colour.
Here's a few I prepared earlier smiley

img_5294.jpg

Michael Gilligan20/07/2018 08:46:03
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Posted by Eccentric Engineer on 20/07/2018 08:34:43:

Hi All

Just thought I'd clear up a slight misunderstanding about the brown colour of the Turnado tool posts.
They don't come from the casting plant like that; after I machine them I send them for a black oxide surface treatment and that's how they come back.
Steel turns jet black in a few minutes but for some reason cast iron only goes a deep brown < etc. >

.

Thanks for the useful clarification yes

MichaelG.

.

Edit: idle curiosity has just led me to find this discussion: https://www.finishing.com/26/97.shtml

Edited By Michael Gilligan on 20/07/2018 08:59:47

John Haine16/12/2018 18:20:52
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Well I was really interested by this thread and thought it would be nice to have something like this for my little Unimat. I didn't want to fit it on the Myford because the toolpost doesn't get moved off that unless I really can't avoid it since all the tool calibration would be wrong. Unfortunately the official versio won't fit such a small lathe, and having just made a tangential toolpost/holder I thought it might be neat to make my own miniature version.

img_20181216_170530493_hdr.jpg

I found this nice steel plate with the two faces turned flat and parallel in the material I inherited from my dad - very dirty and a few dings but cleaned up nicely. Clamps to a bar under the bed with a csk M6 bolt. I thought that I'd need to mill a vee slot on the underside but found that the small flat on the top of the "prism" of the front bedway is co-planar with the real way.

img_20181216_170506989_hdr.jpg

This is the tangential holder bolted down to a 1/2" brass block, also found lurking in the scrap box and machined all over, and down to a thickness to bring the tool tip easily to centre height. Brass slides easily on the steel plate. Note that the block projects under the tool tip so there's no tendency for it to tip when cutting.

img_20181216_170520235_hdr.jpg

First attempt at turning a bit of brass rod (after sucking up all the swarf).

So I feel slightly bad about copying at least the principle of Gary's design but couldn't have bought one to fit anyway. I can feel a pen coming on...

Michael Gilligan17/12/2018 08:22:37
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That's excellent, John yes

MichaelG.

Ian S C17/12/2018 10:23:21
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7440 forum posts
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I think the colour of the cast iron is not caused by the lack of carbon in the metal, but by the excess of free carbon, what ever, I like the colour, hope it is durable.

Ian S C

OuBallie17/12/2018 15:36:47
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1141 forum posts
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Posted by Ian Parkin on 19/07/2018 22:10:22:

I had never realised that cast iron would come out of the mound looking like this ...die cast yes but not cast iron...I cant imagine what causes the colour

49dedc10-cd75-4b61-9856-4a3d2a658a62.jpeg

Ian,

With the correct moulding 'sand' just about any but the finest detail will come out, provided the CI is up to scratch.

Geoff - What a wasted year I've had 😪

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