Compressor Refurbishment – Part 1

I’ve been looking for the best way to get more compressed air in my shop for a while. In the near term, it’s because my mill can keep my California Air Tools 1HP unit running pretty much constantly when using air blast, but in the long term I’d like to be able to paint or sandblast, run air tools, etc.

The other factor is that since this is at my house (which is next to a public park) it’s gotta be quiet. A truly quiet unit with a rotary screw compressor is out of my budget, even used. Pretty much everyone agrees that the best option for a quiet (and durable) reciprocating piston compressor is a Quincy 325. So I started my Ebay hunt, and after a few weeks turned up the unit above for $180 (plus freight, which ran me about $250).

Once this thing showed up, it was in sorry shape.

  • Air pressure gauge busted.
  • Motor burned out.
  • Rust on pulleys and water inside the compressor air lines (possibly inside the compressor itself).
  • Pressure switch snapped off.
  • Tank is very rusty inside.

The first order of business was to see if I could get everything working, which started with putting it somewhere I could work on it inside. That meant adding wheels, which I welded on with my AlphaTIG 200X, using the stock SMAW setup and 6011 rod, running at about 90 amps (DCEP).

The next step was rebuilding the entire electrical system , putting in a new motor, and trying to turn the unit on (with the tank uncapped, more on that later). Since I’ve only got single phase, I picked up a 4kW VFD which takes single phase input and provides three phase output. This is a cheap Huanyang unit (actually a rebranded or knock off unit made to the same specs, based on the manual and some Google-fu), but I expect it will do the job since I don’t expect to push this unit very hard. I also checked the crankcase oil level and filter, both of which were fine (although the oil is milky, I’ll replace it and the filter later), and replaced the air filter with a low-noise intake from Solberg.


All together and ready to run. That galvanized box on the right hand side has the VFD and breaker in it, and you may have noticed the shoddy wiring job to my welder outlet. That’s just for testing.

Turns out the crankshaft is bent. Apparently a common issue with this units if they’re shipped improperly, because they’re top heavy. I wouldn’t be surprised if this unit would last for years for my needs running in this condition, but it’ll definitely shorten the bearing life, and probably the belts’ lives as well.

Guess it’s time to tear the unit down the rest of the way. It’ll also give me an opportunity to inspect the internals and replace anything that may have an issue.

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