I don't rave about tools much, (except for my Ellis bandsaw!!!) but I gotta say that if anyone is going to be doing some sandblasting this spring and is looking for a low dollar siphon feed setup, RUN to Tractor Supply and get their JobSmart Siphon Feed Abrasive Blaster. It's $19.00. You stick the pickup hose into a bucket and go to work.
I just ran 400 lbs of 00 sand through mine, spot blasting the Oshkosh truck cab that I'm working on, in preparation for lead work. It never clogged, burped or otherwise caused the normal frustrations that blasting always includes. I've had all the other ones. Craftsman, HF, CH, etc. They all suck to the point that you want to throw them as far as you can as soon as you get your hood off. I've also got a 700 lb Willard Blaster that takes a 125 CFM compressor to run it.... way too much work to set that beast up for little work.
I'm going back to Tractor Supply tonight and buying all that have in stock. Just like good work boots, this thing will be discontinued in a flash.
How big a compressor do you need?
From my home sandblasting experience, most "hobby size" blasters need about 10cfm (3+ horsepower minimum) to hold close to 90 PSI. The more worn your nozzle, the more air you use. If you regulate the operating pressure down to work on something like sheet metal, you will use less air but material removal will suffer as a result.
I bought a 5 hp that seems to be an all arround size to do most if not all jobs around a shop. As far as sandblasting is concerned it depends on at least 90 lbs at the nozzle using fine sand such as no.9 which is what's called sugar sand by some. Don't use any thing less finer than that. The coarser sand usually has larger grains from time to time which will stop up the nozzle. You have to be careful with sheet metal as you can warp it if your not careful. And the most important thing to do to to wear a face mask of some type to prevent breathing the dust! Once it's in your lungs you can't cough it out no matter how hard you try! A BANDANA WONT DO IT.
2 other things; make sure the medium is dry and if you re use, don't forget to screen. We have a siphon feed at the shop and biggest issue is larger chunks fall in the hopper and get picked up, plugging the nozzle. Even in a closed cabinet, does not hurt to screen the medium every so often. So only use to remove rust, have the item grease and crud free but even chunks of paint can block the system.
The label may say "Fine", but I've learned that it saves me grief to screen the sand before I use it. When that supposedly fine sand clogs, you spend more time dealing with that than it takes to screen the stuff ahead of time.
Try water sandblasting. Gas power pressure washer with 4 gallons per minute. Uses suction hose in bucket. Now you've got 2500 psi instead of 120. Works well and is fairly portable. You got to be ready to the rust to start almost immediately. Good on cast iron, frames, etc. Good on sheet metal because it does not heat up.
I have a sand blast cabinet that I never run over 45 lbs of pressure. It is not about the air pressure, but more about the abrasive that you use. I have run at higher pressures, and all I did was pulverize the blasting media.