Casting iron using Thermite instead of a furnace

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awemawson:

--- Quote from: philf on January 29, 2013, 03:39:32 AM ---
--- Quote from: awemawson on January 29, 2013, 03:14:49 AM ---I have some stainless steel foil that I use to prevent scale when hardening & tempering. Just like cooking foil but stainless steel not aluminium. Works a treat but is lethal, vicious stuff that cuts your hands as soon as you look at it. Wrap the piece up in it like a pastie, ie fold over the edges to make a seal. Include a little sliver or two of pine shavings to adsorb the oxygen from the air inside as it is cooked, and bits come out pretty clean and unscaled.

Andrew

--- End quote ---

Hi Andrew,

I've heard of this before. How thick is the foil you use? Where do you get it from?

I just did a quick search and the only prices I could find were horrific.

I also read that borax works well in preventing scale but that you can have as much trouble removing the borax as you do the scale. I wonder about using silver solder flux.

Cheers.

Phil.

--- End quote ---

I cannot remember where I got it - possibly JLA - I know that it was horrendously expensive, and there was a minimum order so I ended up buying two rolls but that was maybe ten years ago. It's probably about half a thou thick maybe less.

If you can find a tin with a slip over lid (as opposed to a press in lid so not pressure tight), and cook your parts in it but add wood shavings to absorb the oxygen you can get a similar result. You could also fill the tin with argon if you have a welding set - all you are trying to do is heat the item in an oxygen free atmosphere to stop the metal oxidising. Salt baths are another way of achieving the same thing but more fiddly to set up for a one off.

Andrew

philf:

--- Quote from: awemawson on January 29, 2013, 06:40:52 AM ---I cannot remember where I got it - possibly JLA - I know that it was horrendously expensive, and there was a minimum order so I ended up buying two rolls but that was maybe ten years ago. It's probably about half a thou thick maybe less.

If you can find a tin with a slip over lid (as opposed to a press in lid so not pressure tight), and cook your parts in it but add wood shavings to absorb the oxygen you can get a similar result. You could also fill the tin with argon if you have a welding set - all you are trying to do is heat the item in an oxygen free atmosphere to stop the metal oxidising. Salt baths are another way of achieving the same thing but more fiddly to set up for a one off.

Andrew

--- End quote ---

Thanks Andrew,

I found some SS foil at Goodfellows but the cost wasn't just horrendous it was unbelievable.

As I just said in my reply to Norman I'll do some experiments later on scrap pieces rather than on my delicate pinions.

I realise I'm off-topic with this subject!

Cheers.

Phil.

Fergus OMore:
I was giving the old grey matter a jolt following your comment about soap- and I seem to recall LBSC using soft soap( whatever that is or is still available) but if that is the case( pun) any decent oil based paint or varnish should have much the same ingredients- vegetable oils etc.
My experiences tie in with welding /silver soldering and using pencil lead /graphite to limit runs. My wife taught me :wack:
It all seems to tie in with casting and using graphite between the greensand and the casting .

Worth a try on something on a dummy run?

Meantime
#
Cheers

N

Pete.:

--- Quote from: RobWilson on January 28, 2013, 04:40:44 PM ---I have a 25Kg bag of Iron Oxide powder (dont ask) if anyone wants to play :zap:

Rob

--- End quote ---

You must be scraping it off all that rusty old stuff you keep posting pictures of here!

Rob.Wilson:

--- Quote from: Pete. on January 29, 2013, 04:58:51 PM ---
--- Quote from: RobWilson on January 28, 2013, 04:40:44 PM ---I have a 25Kg bag of Iron Oxide powder (dont ask) if anyone wants to play :zap:

Rob

--- End quote ---

You must be scraping it off all that rusty old stuff you keep posting pictures of here!

--- End quote ---

:lol: :lol: :lol: :lol: :lol: you got me Pete :lol: :lol: :lol:

Rob

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