blasting media -- what do you use?

[milwaukeephil]

Hi guys,
I got a bug up my ass to finally build a small blasting cabinet this weekend for cleaning parts that I want to powdercoat / paint.

There are a ton of different choices as far as what to use for media -- I guess I'm looking for something that's not too aggressive, since I'd like to be able to strip old paint and powdercoat from steel and aluminum parts.

I'd love to hear what you guys use for this purpose. I.E., is aluminum oxide okay? Any certain grit?

Thanks,
-phil

[okie88]

I have used several kinds of media in my cabinet (Harbor Freight) and here is what I think I have learned:

Aluminum oxide - The instructions that came with my cabinet said not to use aluminum oxide in the cabinet. They didn't say why, so I, being pretty hard headed used it anyway. It seems to be very aggressive and you get a lot done quickly. It is also pretty aggressive on the inside of the window. Not good. It seemed to take an electrical charge and stuck to a lot of stuff that I didn't want it to stick to. It was really a mess to clean out of the cabinet. I quit using it and will probably never use it again. A 25 pound bucket cost about $30.

Fine sand - Seemed to be the best for removing paint. It is pretty aggressive and will pit aluminum pretty badly, so you are limited to using it with steel parts. It had the advantage of being a LOT cheaper than anything else I have tried. An 80 pound bag cost under $5. I am sure I will use it again.

Glass Beads - Seems to be the best all-around media for working on motorcycles. It removes paint well and I have been happy with it on both steel and aluminum. I used it to blast the hubs on a CB350F and after just a little bit of polishing they looked better than brand new. A 50 pound box cost $40 at Harbor Freight.

Walnut hulls - I'm not sure, but I believe this is intended for soft items like aluminum and brass. I just bought it to experiment with and have come to like it a lot. It really cleans up things like the plastic side cover knobs. It is the only media I have used that can be used on chrome without dulling it. I used it on my Super Hawk hubs and was pretty happy with the outcome, but I think the glass beads work better. This is the only media that doesn't seem to care about moisture in my compressed air. It never seems to clog or clump. Even though it cuts more slowly, I would rather use it because of the non clogging factor. A 25 pound box cost $30.

If I didn't have the blast cabinet I would NEVER buy another basket case. With the blast cabinet I can restore old, ugly parts and make them look at least as good as new ones, sometimes better than new. I use a shop vac on the cabinet to keep a negative pressure on it so very little media escapes for me to breathe. It sure is handy to have that capability 15 feet away from my workbench.

[milwaukeephil]

Cool, thanks for the reply. I think I'll start with glass beads. How much do you go through? In other words, how long does a bucket last you?

Thanks!

[milwaukeephil]

Oh, and do you have a filter over the vac hose? does it suck up the media?

[okie88]

50 pounds of glass beads should be enough to blast everything except the frame on a really UGLY Super Hawk project. I excluded the frame because it won't fit in my cabinet anyway. (Actually, I DID blast it in my cabinet, but that's another story.)

The place where the vac hose attaches to the cabinet has a sheet metal cover that helps reduce the amount of media lost to the shop vac. I drew a rough sketch for you. The cabinet SHOULD be constructed so it has essentially, NO LEAKS, so the only source of incoming air will be the compressed air, feeding the blast nozzle. That means there won't be enough flow volume going to the shop vac to loose much of the media. I have to empty and service the shop vac approximately every 20 hours of use.

[Scottie]

I've have a second-hand blast cab that came with used alum oxide media, and I bought some 80 grit glass bead media that works pretty good on sheet metal and aluminum heads, etc. It doesn't work that well on frames with good paint, though.

Been using a shop vac to pull a neg pressure, too, otherwise everything in the shop gets covered with dust.

I'm planning on using the al oxide on the frame, so I'd like to hear your story on that. I was planning on just putting the hose in the bucket with the oxide and blasting it outside.

Scottie

[okie88]

My neighbors would have a fit if I blasted in the driveway. If you have never blasted outside, I suspect you are in for a surprise. A lot of those little veads will bounce back off of the frame and try to blast all of your skin off. You will need a good respirator, protective long sleeves, gloves and good eye protection. It really makes a mess.

OK. here is my major redneck, okie frame blasting solution:

I removed the door on the end of the cabinet.

I put as much of the frame in the cabinet as would fit.

I duct-taped a heavy duty lawn and leaf trash bag around the protruding part of the frame, sealing it up against the cabinet.

I blasted everthing I could get to in that position.

NOTE: If you are using a vacuum you will loose very little blasting media around the cracks that you didn't get taped perfectly. It really sucks the bag in tight on the frame.

I removed the trash bag, repositioned the frame, replaced the trash bag, and blasted a new section of the frame.

Repeat as necessary until finished.

The cheapest local blaster wanted $175 to start, and possibly more based on the time required. He couldn't get to it when I wanted it. I am a VERY determined person(according to my wife, hard headed). I wanted it done that day, ant that is exactly what I got.

One thing I would recommend, is to spray every part of the frame with aerosol paint stripper. Let it cook for a while and then wash it off with a high pressure washer. That will make the HARD TOUGH paint on the frame a lot easier to blast.