To make the Harbor Freight pressure blaster work I did this.
1) Pre-screen all your sand thru an old window screen & 5 galllon bucket. You will catch a LOT of large pieces that would have clogged the tip.
2) Change all steel valves to brass valves.
3) Clean out the little "chips" of assembly metal carelessly left when the Chinese workers cut the pipe threads. I got about 10 metal chips out.
4)Most important is a small rubber gasket just behind the white porceline tip in the gun. Remove it and replace it with rubber washer, or an "O" ring, or just wallow it out on the inside to a larger inside diameter hole. This little bogus thing was trapping sand and clogging cause it squishes too tight and the inside hole gets too tiny.
I buy bulk "fine" sand from a quarry for 3 dollars a 100 pound bag, and after I screen it for stray large particles, it has worked perfect.
My HF pressure blaster has done everything from rusty wheels, to valve covers, exhaust manifolds, and fenders, etc FANTASTIC. But it needed the aforementioned re-working!
I first thought my problem was too much humidity, but I sandblasted on a horribly humid day and got very little clogs from the water.
I used 65-85lbs pressure from my 5hp 20 gallon compressor and everything worked super.
Professional sandblasters told me DO NOT attempt to blast your hood or any other relatively thin expanse of sheet metal that needs a super smooth paint job (they hate trunk decks too) until you are an Expert plus. Most rounded, real thick AD truck parts are OK; BUT experiment first on big thick stuff like wheels, or parts that wont show a "wave" that a poor sandblast job might put into really thin metal.
Good luck, hope this helps
john
1952 COE 2 ton
1947 COE semi
