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(03-20-2018, 09:03 PM)®smpr_fi_mac® Wrote: Can a compressor duty motor be used safely on a band saw in a hobby shop that only sees use minutes at a time?
Most compressor duty motors are open type. You'd want to be diligent about keeping the dust blown out. They also tend to have low starting torque and very optimistic HP ratings. Probably not the absolute worst choice for a band saw but a compressor motor would be very low on my list of acceptable motors.
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NEMA does not define "compressor duty". It's a marketing term, not an official designation. In fact, the data sheets and curves I've seen from (I think) Marathon showed lower locked-rotor and pull-up torque values than similar continuous-duty cap-start motors of the same frame and power rating and manufacturer, probably because compressors have low inertia (high reduction ratio drives) and start without load (unloader valve bleeds off residual pressure at shutdown) and just don't need a muscular start-up. They also tend to run for shorter duration, not counting industrial compressors. They may have the "time" box left blank, where a 'normal' motor would have "continuous" or some time rating, like 30 min, 60 min, etc.
Other than resawing, BS work is pretty easy on a motor. Looking back, I seem to recall that most issues people have with their BS motors is overheating and tripping the internal OL protection, if it has it (or burning it up if it doesn't) while resawing, which can be overcome by monitoring the current while running it hard to get a feel for how hard you can push it. Sticking a larger motor on it so it doesn't work as hard as a percentage of its rated output (and current input) is always an option.
If I ever bought a motor from HF (for example), I'd just get something larger than needed and let it loaf. Internal winding insulation life (in hours) is reduced/increased by a factor of two with increases/decreases of operating temperature by +/-10 deg. C. So letting it loaf, and giving it rated or close to it voltage under load, and keeping the dust out of it, will give you virtually unlimited motor life in a hobby shop.
Pushing it 'til it smokes, well, set an egg timer, regardless of motor type.
Tom
“This place smells like that odd combination of flop sweat, hopelessness, aaaand feet"
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Ah. Cool. Thanks!
Semper fi,
Brad
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I put an 3 horse HF "compressor duty" motor and riser block on my 14" saw several years ago so I could re-saw 1/4" oak panels. I've never had so much as a moment's trouble with it.
