[machine shop tom]

I purchase da used George Olcott blast cabinet. It has a media reclaimer and a separat vacuum filter unit. It's quite big (I'll measure it tomorrow and post the dimensions). I don't have it hooked up yet, but it should work good. I plan on using glass bead media in it. I read recently that boring bar shavings/chips work well. I'll have to try that at work.

tom

[47chevy]

I worked for an aluminun casting company and they had to prep the steel molds for the coating material before any molten aluminun could be poured into them. They used the excess aluminun saw chips. I did blast some car parts and it worked excellent, left a super nice finish and there was very little heat build up.

[oldred]

Aluminum chips, now that is interesting. Seems like they would be hard enough to remove some heavy coatings and maybe even do a good job on rust but should be soft enough to not peen the steel. How big were these chips compared to sand?

[47chevy]

The longest chip was about 1/4" long, 1/16" wide and 1/16" thick. They used large band saws to cut the excess aluminun off the castings. I think the blades were 10 tpi. The chips suprisingly lasted for several weeks. The molds had about 1/8" coating of release agents by the end of the week. After they were blasted it did leave a super nice finish. When you produce close to a million parts from each mold the main concern was that the blasting material could not remove any steel or damage the interior finish.

[pepi]

Originally Posted by oldred

should be soft enough to not peen the steel. How big were these chips compared to sand?

what is the down side of this? I thought that peening steel or cast would prevent rust

[oldred]

Originally Posted by pepi

what is the down side of this? I was thought that peening steel or cast would prevent rust

Only a problem on thin parts like body panels, Sand and other hard media will peen the surface and cause thin panels to warp that is why it is so difficult to sandblast rust from most car body parts without warping them.

[capta1n]

I found a used Trinco blast cabinet from an engine shop which was closing. It is a great piece of equipment.
Each media you use will have a recommended pressure rating. Ask the supplier about the pressure recommendations. Of course you can run at a higher pressure, but the media will not last as long.
I will gather a number of parts to be cleaned(rust, paint, whatever) and use a media called barshot. It cleans metal like nobody's business, but does not leave a smooth surface. After I have everything cleaned, I empty the cabinet and shoot everything with glass bead. This step leaves a very smooth surface ready to be wiped clean and painted.
I have purchased media from http://www.grandnorthern.com/. I can pick the media up when I am traveling so I don't have to pay for shipping.
Good luck.
j.L>

[pepi]

ok so peening is the process and a generic term like media, all right then ... thanks

[oldred]

By peening I mean the sand (or other media) will strike the metal like millions of tiny peening hammers and distort the surface causing it to stretch or "grow". When one side of a thin panel is stretched in this manner it causes the entire part to warp unless it is thick enough to withstand the stresses. A good example would be a Mustang trunk lid that I literally destroyed a few years ago with a sandblaster. I was aware of the warping problem but had little experience with metal as thin as that and even trying to be careful I managed to warp it so badly I had to scrap it and buy a new one.

[Dugg]

I once bead blasted a pair of old Corvette valve covers at the shop, took'em home and they wouldn't fit back on the motor. I took'em back and this time blasted the insides of the covers and they rebounded or warped or un-pinched or ? and fit after that.

I would be hesitant to buy a cabinet that folded up when not being used as I picture it blowing media out all the joints all over the place.

Don't use silica sand. It's worse than smoking a pack of Luckies an hour on your lungs.

Were I work part time, we sell two kinds of media, one is a sand quartz mixture (as I recall, I'll check) and the other is a fine weld slag. The body shop guys in the area buy it.

Wear a respirator or the better of the 3M masks - the ones with the metal strip across the nose and two bands. I don't like the Harbor Freight masks as I don't want to be the first one to open the bag and breathe polluted Chinese air...lol

[oldred]

Originally Posted by Dugg

I don't like the Harbor Freight masks as I don't want to be the first one to open the bag and breathe polluted Chinese air...lol

You may be saying that for a joke but with all the poison goods (GOODS?) coming from China lately, everything from pet food and toys to mouth wash and tooth paste, I have to wonder what may be in those masks. I would not use, nor never would use, those masks and I would not be at all surprised to find they are more dangerous than some of the things they are used for, coming from that place you just never know!