I finally put together the Harbor Freight special sandblasting box and need a bit of advice. What media should I use and where should I buy it.
My first work will be carburetors but I'm also interested in recommendations for various work with Model T's
For delicate work such as carburetors, I would use glass bead. I have the floor model blast cabinet from H.F. and use the aluminum oxide 80 grit. This would be a little aggressive for carbs though. You can play around with air pressure but most of us don't have compressors with enough capacity to play that game. Most blast cabinets need at least 90 psi to work well and most residential compressors struggle to maintain that with a blast cabinet in continuous use for more than a minute or two.
I get mine at Tractor Supply--black oxide, heavy grit. I agree, different media for different things. Of course you can use the gritter used media for finer things as it breaks down and gets finer. Just save it for future use.
Also agree, unless you have a compressor to back it up, most will run under pressure anyhow---mine does. But it works, I just plan a day around it as it takes longer with lower pressure and I try to do everything I need in one shot.
I hope you used caulk or sealer between the seams upon assembly. It cuts down a lot on stray media escaping--although it still does. Wear a dusk mask and do not use play sand for blasting.
We use glass bead. We like about 40 to 45 psi. Anything more and you just turn glass bead into glass powder. They make it different grits, we would prefer a very fine grit for carburetors.
Our cabinet has an attached vacuum to remove dust. We have modified the cabinet with window screen in front of the windows to keep the blast media from scarring the glass.
We also use a scroll compressor that delivers 25 cfm at 150 psi, but we use a pressure regulator to dial it down to the 40 to 45 psi. The scroll compressor is rated for 100% duty cycle as opposed to many piston compressors that can have a duty cycle of as low as 20%
In addition to old cars, we do motorcycle restoration which involves lots of aluminum, which is pretty soft stuff if you try to get to aggressive.
If you remember that it is the media that removes material, not air pressure, and using different grits and types of media, you will have much better results than just throwing something in there and turning up the pressure. In fact blasting is a lot like painting, good equipment and learning how to use it is the key.