walnut shell abrasive blasting question

Greetings Walt, Though I have not done this I have ground other hard things in a coffee grinder. Hard stuff will get finer than relatively soft stuff. But instead of the coffee grinder how about a food processor from Goodwill or some other thrift store? Much larger capacity and I bet cheaper too. The blades in a food processor are much stouter and will be less likely to break. Cheers, ERS

If you use an old-style coffee grinder you will get more consistent results than with the mini-food-processor types or a full scale food processor (both of which make a lot of fines); at least it works that way with coffee beans. By old style I mean a hunk of cast iron where beans (or walnut hulls) go in the top hopper and ground material comes out the bottom, coarsness adjustable by turning a wing-nut, generally. Used to be big power units at the A&P checkout, the one I use is a hand-crank.
Assuming fines are either bad or useless, the other mill to look at for crunching stuff down might be a grain-crushing roller mill as the homebrewers use. Pretty straight-forward metalwork project, I think.

I have used hardwood sawdust in my blaster with good results mostly for degreasing and cleaning machinery. Might work for your application.

Yeah. That other kind would be great. I wonder where to get a cheap one? Maybe a restaraunt supply? ERS