By Channing B. Mould
For quick removal of paint and grease from metal surfaces, you can't beat a sand-blast machine. E VER try to clean the paint off a motorcycle wheel? Or, for thatmatter, any other metal object? Well, if you have occasion to do such work, you will find a small sand-blast machine worth its weight in gold. If you have a handy source of sand and a reasonably goodsupply of compressed air, the rest is simple. A sand blaster is merely a tank that will safely withstand the pressure of the air supply. It has provisions for pouring sand into the top and allowingit to trickle out the bottom, where it is entrained in a stream of air. It is necessary that the tank be pressurized to prevent the air that flows to the nozzle from blowing up through the sand supplyinstead. The machine illustrated was constructed of a 14-in. length of 6-in. pipe with 1/4-in. plate for the ends. The only part of the machine that cannot be made with hand tools is the filler holein the top plate. This hole must be made to properly fit whatever object is used as a stopper. The author found a 3/4-to-2-in. reducing pipe coupling
to be the simplest thing to adapt. Thestopper must have a tapered portion that will produce a wedging action when air pressure is applied. The hole in the top plate, then, is machined to the size that will allow the tapered section of thestopper to seat. The underside of the hole should be chamfered a little so the gasket won't be cut by the pressure. A little allowance (about Vs in. on the diameter) is made for the gasket material,which, in this case, was two layers of automobile inner tube cut in rings and slipped down over the stopper. Weld in the bottom plate first by recessing it sufficiently to allow a good fillet weld. Now isa good time to drill the holes for the piping because it is easy to burr the inside and clean out the chips. With the stopper and its lever assembly in place on the top plate, tap the plate down...