[Supras] Air compressor

[berniek at technicaldevelop.com]

Whatever you do, do not get a compressor with a single unit motor-compressor.  The motor runs at 3450 RPM, and the noise from the reed valves and vibration in the compressor will drive you nuts.  A belt driven two cylinder compressor is much better.  A dual stage unit is not a necessity, but it will keep the flow up at high pressures.  

The compressor itself should be cast iron if possible.  Some of the cheaper units are die cast aluminum (probably OK, but look for iron cylinder liners) or "pot metal" (weak stuff).  

The one I have here is based on a large truck air brake compressor, with an internal oil pump and cooing fins rather than a water jacket (both are rarities, but it came out of a junk yard for $5 about 25 years ago).  At that time Grainger sold receivers (tanks), pressure switches, safety valves pretty cheaply, but I'm afraid that has changed.  A good source of decent motors is also a general type junk yard, if you get friendly with the owner and can walk in with a toolbox at lunchtime, and take what you need from equipment scrapped for reasons other than the motor.  I got a pile of motors, oil burner parts, good hot water heating circulator pumps from scrapped boilers and other stuff really cheaply at a local yard here in Dover, NJ.  

I got a needle scaler, pneumatic shears, and a portapower style hydraulic pump from Harbor Freight (was Harbor Freight and Salvage before they changed the name).  The stuff is usable, but quality is far from the best.  If you buy a compressor from them, make sure the motor is thermally protected, has ball bearings and has a temperature rise rating of no more than 40C (if published).  The compressor should also have ball bearings.  Radial loading from the belt drive will wear a front sleeve bearing pretty fast if splash lubricated.  

Good luck.  

    BernieK