I see I sent this to the wrong address originally.
Try again.
I have a requirement to cast a special Aluminium* part. Very low tech
and low tolerance requirement. Precision and material composition are
suitably undemanding that I may even be able to do it with no prior
experience of metal casting. But maybe not :-)

Any comment on home casting to meet my requirement would be of
interest. If this is ever going to happen (and odds are it isn't) it
would have to be reasonably easily accomplished. This seems possible
but past experiences with Murphy suggests otherwise.

This page offers large amounts of apparently useful material on the
subject.

        http://www.backyardmetalcasting.com/index.html

This page offers some brief but useful advice re the effect on iron
content caused by using iron crucibles.

        http://www.smokstak.com/forum/showthread.php?t=33715


            Russell



___________

FYI I'm (only) considering casting a "heat sink" for my wood burner to
greatly improve it's useful heat output. This is a metal box with a
high temperature 'glass' door. The firebox hangs inside a larger steel
air sleeve. As built heat output from the fire is a very small
percentage of that produced by the fire.

Only the external top of the firebox is easily accessible.
By placing various forms of heatsink on the top of the firebox and
then blowing air around the air sleeve we get far far more heat out -
probably about 5 times as much - maybe more. The informal heatsinks
are OK but it's obvious that if I fitted a single heatsink covering
the whole top of the firebox and suitably finned it that I could get
an optimum amount of heat out by adjusting air flow. A cast aluminium
top plate 'simply' needs to make good enough contact with the steel
firebox top and have adequate finning. Fin surface need not be high
quality or even especially even. The plate bottom may benefit from a
post casting 'skim' but if it can be flat within a few mm overall it
would probably suffice.

Top surface is about 500mm x 500mm and total available height for
heatsink is about 90mm. That's a LARGE heat sink by most standards.
Doing this with commercial heatsink sections (even available surplus
ones) would be prohibitively expensive.

Heatsink could be cast in several smaller sections. Depending on fin
to total volume ratio this could get rather heavy. Space described
above is about 25 litres. At a 20% volume fill that's about 14 kg of
Al. How dense the finning can or should be depends on airflow
requirements and I haven't yet come to grips with what's required to
calculate this. A modestly forced blown system (as at present) is
probably best. The upper limit on air blowing rate is my wife's (low)
tolerance of fan noise.

An alternative is spot welded thin fins on a thickish Al sheet. Gets
quite expensive if you can't utilise scrap.



* Where you are it may be an Aluminum part. Here it's not :-)


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