On Nov 30, 7:13*pm, Jim K wrote:
On Nov 30, 2:25 pm, Andy Dingley wrote:

For cleaning metal, the only thing I've found useful is a pressure-pot
gritblaster. You can make these yourself (steel drum, pipe fittings)

that sounds cool - any links/pointers/info please?

Searching for "pressure pot sandblaster" should show up enough to do
it. Don't be fooled by venturi or syphon designs instead.

You need a pressure-proof steel drum (full working pressure), so a gas
cylinder is the likely favourite starting point.

Weld on some legs as a raised stand and also some pipe fittings. 1/2"
steel pipe and full-bore ball valves (big handles, you'll be working
in gloves) At the bottom you need .a pipe fitting, at the top you need
another pipe fitting and the biggest screwed plug filler you can find.
You're making a big steel 90psi+ pressure vessel here, so the welding
has to be spot-on and you ought to hydraulic test it afterwards...

At the bottom you plumb a tee piece. One side is the output through
some heavy rubber hose and a steel pipe output nozzle (plain tube is
fine). Ideally buy some hard ceramic commercial nozzles and use
those. The other side of the tee is air supply, which comprises a hose
from the compressor, a second tee and two ball valves and then
connections to top and bottom. You have to fiddle the valves manually
to adjust air/sand flow rates. If you're lucky, you can replace these
with fixed pipe of exactly the right dimensions (probably after having
used prototype #1 for a bit) and use a single ball valve as an on/off
air valve. Tip: Use some flexy rubber hose to connect to the top
connection, it's much easier to assemble than rigid steel on a fitting
of uncertain alignment.

You _need_ big gloves and a hood (cheap face shield with a fabric hood
attached). You might like apron and full rig too. Leather welder's
jackets (cheap chrome leather) are woorth having.

Use grit, not sand, to avoid silicosis problems. Use the right grit
and change it between iron, aluminium, glass etching and plastics.