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Buzz wrote:
> Several years ago I built a large sandblast cabinet out of 2 sheets of plywood, 1
> sheet of masonite and a weekend of time. I started using sand but changed to
> aluminum oxide, (AO) after talking to a professional blaster. He told me that
> when a grain of sand hits a solid object it more or less explodes into smaller
> pieces creating dust and releasing all sorts of bad things into the atmosphere.
> AO shears apart. making smaller sharp edged particles, and as far as I know, does
> not release the baddies that sand releases. I've been told AO can be used over up
> to 10 times. I use it until I notice a lot of dust in the cabinet.
I use glass-bead media in my blast cabinet. It can recirculate through the nozzle many
times before it has to be replaced. Glass beads don't have a high shatter rate, unless
your pressure is set too high for the nozzle dimensions and bead size. It also happens
to be a comparatively low-mass medium that does not work-harden or stretch sheet metal
as much as a denser media would, and I think that it leaves parts with a nicer finish,
similar to that obtained with vibratory pellet systems, and I don't think that it
breaks down sharp edges as much as a pellet system would.
Silica sand is a good all-around medium. It does break down more quickly than some
mediums, but that can actually be an advantage on sheet metal, since shattering can
limit its impact and its work-hardening effect.
Naturally, you should wear an approved respirator when using blasting media of ANY
kind...not just with silica sand.
Alan
This archive was generated by hypermail 2b29 : Tue Apr 04 2000 - 21:57:04 PDT