Dave Krall wrote that he wanted information on abrasive blast
cleaning of piano action parts.  I have been doing this for several
years.  For the smaller wood parts I like to use a bench top metal
cabinet that is about 24 inches (61 cm) square and about 18 inches
(46cm) high.

I use 1420 Grit-O'Cobs corncob granules from The Andersons in Maumee,
Ohio, USA, web site http://www.andersonsinc.com/  I use 10 to 15 psi
air pressure.  This does a nice job of getting rid of the "crud of
the ages" without doing noticeable damage to the wood unless you blast
too long in one place.  It also cleans up the felt nicely.

For large items I built a 30 inch (76 cm) by 72 inch (183 cm) floor 
model steel lined wood cabinet where I use glass beads and about
60 psi air pressure for brass items like Steinway action frames.
This leaves a fine matte finish.

A couple of things that I found out rather soon after starting was
you need to have very good moisture removal of the compressed air. 
With the pressure drop at the nozzle you will get condensation of
any moisture in the compressed air and your blast media will clump.

Also, don't touch the clean brass with your bare hands until you get
a protective coat like lacquer on it.  The oils on your skin will
leave finger prints.

If you have specific questions please feel free to contact me and
I will try to go into more detail.

John Dewey
861 E 2900 North Rd.
Penfield, IL, USA