Between a pneumatic die grinder:

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and an electric rotary tool:

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What are the advantage/disadvantage between using each one?

Also, which has more torque?

2 Answers 2


Pneumatic may be lighter weight, but you need a compressor that can keep up with it, and the exhaust airmay be a good or bad thing depending on what you're doing. On the other hand, compressors have other uses too.

A third option would be a flex-shaft tool.

Before buying any of them, know what you're going to do with it. Unless you have a specific task you need it for, you might be better advised to invest in a completely different kind of tool.

  • Right now, I'm mostly using it for cutting and grinding. In the future, I might also build an CNC, based off on an open design, for machining metal parts. So torque will be an issue. I've always thought that pneumatic rotary has more torque per size than electric ones, so I kinda lean on the pneumatic one. I also need an air compressor anyways, though if it's going to be used as CNC, the volume of the air tank needs to be quite high.
    – kozner
    Dec 19, 2015 at 5:02
  • The third option you mentioned also seems good, since I already have a bench grinder. It crossed my mind, but it just seemed too crazy. Then again, since I'm already hacking and slashing everything, I might as well make an adapter for it so I can attach a flex-shaft... Though if you wouldn't mind, could you tell me the advantages and disadvantages of going with this option.
    – kozner
    Dec 19, 2015 at 5:06
  • For CNC you probably want a real router motor -- at least a trim router, from what I've seen... for higher speed and torque than either.. For continuous use, you want a larger compressor as well as larger tank, though the two do generally go together.
    – keshlam
    Dec 19, 2015 at 5:06

pneumatic tools can run for days and never get hot, but the compressor gets hot. from a power consumption perspective, electric is much more efficient. pneumatics have to be oiled regularly and create condensate issues with water in the discharge exhaust. pneumatic is really just an old technology that is becoming more and more obsolete all the time. still great for painting, but electric is pretty much better in every way. for a cnc, you can get water jacketed motors that run high speed and torque for hours at a time.

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