Lost Foam Casting - Follow Up

Grant,
I don't use a flux/degassing chem (yet) though have 2 types in transit
w/200lbs of petro-bond...
But I'm unsure of what difference they will make, as I'm casting out
of steel crucibles, and using a steel ladle to skim the dross. I
understand that this is a poor combination as it tends to intoduce
hydrogen bubbles.
On the positive side, I did get 3 out of 5 larger pours to come out
very nicely using 16" deep boxes, and better compacion of the sand.
Details posted at:
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Also I'm getting some folks telling me that I should invest in a
Pyrometer, as the window of opportunity with to pour is far narrower
than one would expect... I found a place in Toronto that has them for
about $600 Cdn...
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That is where the petro-bond and flux is coming from.
Frank
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Reply to
Frank
Loading thread data ...
Grant,
I don't use a flux/degassing chem (yet) though have 2 types in transit w/200lbs of petro-bond...
But I'm unsure of what difference they will make, as I'm casting out of steel crucibles, and using a steel ladle to skim the dross. I understand that this is a poor combination as it tends to intoduce hydrogen bubbles.
On the positive side, I did get 3 out of 5 larger pours to come out very nicely using 16" deep boxes, and better compacion of the sand. Details posted at:
formatting link
Also I'm getting some folks telling me that I should invest in a Pyrometer, as the window of opportunity with to pour is far narrower than one would expect... I found a place in Toronto that has them for about $600 Cdn...
formatting link

That is where the petro-bond and flux is coming from.
Frank
formatting link
Reply to
Frank
Re: flux and degasser
Two cheap tips for aluminum casting:
(1) Use canning or rock salt as a flux when melting. It will float on top of the melt protecting the aluminum and if the charge is salvage metal it seems to cause the contaminates to separate so these can be skimmed or sink to the bottom. Learned this from watching an aluminum salvage operation.
(2) For degasser, fill a piece of =BD inch black iron pipe about 4 inches long with swimming pool chlorine powder. (much cheaper than the tablets). Use a wad of aluminum foil or brown paper in each end of the pipe to keep the powder in. Use tongs to plunge the pipe to the bottom of your crucible and stir it around. Be careful not to breath the fumes!
If you are getting porosity in your castings, check the pigs/ingots that you pour when the molds are full. If these are sound most likely the metal is too hot.
Try painting the bottom and sides of your foam patterns with water glass (solution of sodium silicate) and let dry. Use plaster or sand to support the coated foam pattern. I can get very smooth surfaces this way.
Reply to
gmcduffee
I want to say that the alum foundry I programmed for used potatoes for a degasser. I do know that they put the potatoes in their melts for something.
Re: flux and degasser
Two cheap tips for aluminum casting:
(1) Use canning or rock salt as a flux when melting. It will float on top of the melt protecting the aluminum and if the charge is salvage metal it seems to cause the contaminates to separate so these can be skimmed or sink to the bottom. Learned this from watching an aluminum salvage operation.
(2) For degasser, fill a piece of ½ inch black iron pipe about 4 inches long with swimming pool chlorine powder. (much cheaper than the tablets). Use a wad of aluminum foil or brown paper in each end of the pipe to keep the powder in. Use tongs to plunge the pipe to the bottom of your crucible and stir it around. Be careful not to breath the fumes!
If you are getting porosity in your castings, check the pigs/ingots that you pour when the molds are full. If these are sound most likely the metal is too hot.
Try painting the bottom and sides of your foam patterns with water glass (solution of sodium silicate) and let dry. Use plaster or sand to support the coated foam pattern. I can get very smooth surfaces this way.
Reply to
jay s
Seems like a good way to get some nice explosions...
BUT, you have to overheat it. If you use an alloy of potassium and sodium chlorides, it'll melt at a more reasonable temperature. Convieniently, Morton Lite Salt (half the sodium of normal salt) is already mixed just so. You have to fuse it (and cast salt ingots ;) before use to make the alloy.
It also seperates the slag, leaving a gray powder rather than a sticky mess of metal.
4" sounds like an awful lot for a single tablet. It's what, one ounce of degasser per 20 or 100lbs of metal?
Or you are stirring too much. Breaking the surface (which is naturally protected by a layer of aluminum oxide) allows in gas momentarily. A lot of movement lets in enough gas to be a problem.
Tim
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @
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Reply to
Tim Williams
[...]
That's officially the funniest thing I've heard of in a long time. I had to run out to the store just to see some for myself, and sure enough, there it was--unsalted salt.
Reply to
B.B.
Yep, kinda contradictory but works for people who need the taste without the sodium. If only KCl weren't more bitter. :P
Tim
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @
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Reply to
Tim Williams
Hey! Whaddabout "low-fat margarine"?
Same schtick, different fork.
-- Jeff R.
Reply to
Jeff R.
And 'no fat' sour cream? I *don't* want to know what's in that.
Reply to
Ken Davey
Ask Gunner. He probably knows how to turn it into home-made C4, for use with primer caps made out of M&Ms and red pepper.
Ed Huntress
Reply to
Ed Huntress
I spotted that the other day in one of our stores; but the one that got me was several years ago when I found "margarine flavored butter" Gerry :-)} London, Canada
Reply to
Gerald Miller
Hmm, could probably use it in an oil burner, but you'd have to melt it first. Definetly not as cheap as diesel (even these days).
Tim (in a vain attempt at drawing things back on topic)
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @
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Reply to
Tim Williams
Hummm how much lactose or glycerine can you get out of that sort of fat? The lactose may likely be suseptibal to nitrating (milk sugar) mannitol haxanitrate. Then there is casein nitrate....
Primers are very hard to make. Most of the simpler compounds require a bit of mercury or other metals to fulminate.
If you are the nervy type..there is iodine and ammonia....
Gunner
"To be civilized is to restrain the ability to commit mayhem. To be incapable of committing mayhem is not the mark of the civilized, merely the domesticated." - Trefor Thomas
Reply to
Gunner
On Sat, 18 Dec 2004 01:15:04 -0500, Gerald Miller calmly ranted:
I was floored a few years ago when a TV ad for "Oil-free Oil of Olay" lotion came on. How dey do dat?
----------------------------------------------------------- -- This post conscientiously crafted from 100% Recycled Pixels --
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Reply to
Larry Jaques
(snip)
Why? It's perfectly obvious, it's all Soy bean extract. :-) ...lew...
Reply to
Lewis Hartswick

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