Onoff
In the land of the unfinished project I am King!
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Do you reckon this would be suitable for casting in brass using the oil sand technique?
What sand & oil btw?
- Thread starter Onoff
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Do you reckon this would be suitable for casting in brass using the oil sand technique?
What sand & oil btw?
oldbikedavey
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Not remotely ! But, then again, I tend to cast in aluminium alloys or zinc. Brass or bronze need a heck of a lot more heat to be pourable, and are an all round PITA....
Using petrobond, but a silica sand/sawdust/linseed oil mix for cores. Bit of pilchard oil in the stuff makes it a touch less tenacious...
DAPPH
as dyslexik as I'm daft
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Could you cast in alu then use the hard alu casting to make the brass mould ?
Do TIG bronze welding sticks ( can't think of the right name just now ) melt at a lower temp and flow better than brass if you use SIF BRONZE flux ?
Kram
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TIG silicon bronze is higher temp than brass.
We were using red plumbing brass which is a higher temp anyway, but the problem is really just the original furnace design.
The shape cant be with drawn from the sand , really only suited to investment casting where the form is burnt out.
If the text ring was seperate, that part is easy to sand cast.
I plan to have another go at this probably in a couple weeks I will get the furnace running again.
Also looked at trying induction again by getting a quartz liner for graphite cruicible but Im not convinced it would help the temperatures much.
We were using red plumbing brass which is a higher temp anyway, but the problem is really just the original furnace design.
The shape cant be with drawn from the sand , really only suited to investment casting where the form is burnt out.
If the text ring was seperate, that part is easy to sand cast.
I plan to have another go at this probably in a couple weeks I will get the furnace running again.
Also looked at trying induction again by getting a quartz liner for graphite cruicible but Im not convinced it would help the temperatures much.
DAPPH
as dyslexik as I'm daft
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Interesting .
Can you varnish spray the item and dust the form with investment powder several times to get a thin bubble free coating then pour in Plaster of Paris or a liquid investment then melt the wax out in the oven and use a low heat metal that liquifies about 450 oC such as tin . I suppose a gold coloured acrylic could also be poured in a vibrbrted hollow form . Have you tried magnesium alloy car wheels as a source of low heat metal ?
oldbikedavey
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Brass melts a good deal hotter than aluminium, so that's a non - starter.
As regards the melting points of the various brazing rod compositions, they will be known by the manufacturers, but are typically between 800 and 900 C, roughly.
Melting cuprous alloys requires either covering flux or a deoxidiser, of you'll just get a load of black oxidised crud...
oldbikedavey
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Aluminium bronzes look quite nice, and are relatively amiable in casting...
Onoff
In the land of the unfinished project I am King!
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Sounds like a fussy sod!
Just to recap on those for new readers:
The head came out amazingly well.
