Using face-mount motor for air compressor

[sld961]

Hi. I have an old 3hp GE motor that I'm planning I using for an air compressor build.

I just got a nice Baldor 3hp motor for basically free, the problem is, it doesn't have a base for horizontal mount, it only has mounting holes on the face of the motor.

Has anyone made a bracket to mount this type of motor horizontally for an air compressor? Or a base that can be fastened to the motor?

 

[Techie1961]

First thing to do is make sure the motor is correct for what you want to do. The mechanics of mounting it are fairly simple but will have to be sturdy. I would gladly take on something like that for fun. The first issue is the suitability of the motor though. Service factor, RPMs, cooling etc. The old motor is a TEFC (Totally Enclosed Fan Cooled) while the new one likely doesn't have the same cooling ability but not sure on it. It looks like a TEFC but doesn't have any fins so not as capable in cooling.

 

[sld961]

The Baldor is TEFC. It came from a Grundfos vertical turbine pump.

 

[Alchymist]

Just wondering how the front shaft bearing would hold up. In a face mout situation there is relatively little radial force, by mounting it on a bracket and using a pully with a belt, the radial forces will be greater.

 

[Techie1961]

Just wondering how the front shaft bearing would hold up. In a face mout situation there is relatively little radial force, by mounting it on a bracket and using a pully with a belt, the radial forces will be greater.

The forces should be exactly the same. Regardless of how you mount it, the frame is considered rigid.

The one issue you might have is that it's a 3450 RPM motor whereas your old one was 1780. You'll need a much smaller pulley.

Edit: sorry but now I see what you were referring to. Most face mounts use a coupling and virtually no radial loads. The design of the motor housing is for the most part the same though with a larger bearing at the shaft end. I suspect it's no different than it's base mounted brother from the same manufacturer.

 

[Techie1961]

You could fabricate an L shaped bracket to hold the motor. The horizontal leg would bolt to the compressor platform and the new motor would bolt to the vertical leg.

There is probably a super good reason why compressor manufacturers do NOT do this.

Just an easier way to build with a foot mounted motor. Common base (the saddle) and the need to reduce the speed with a pulley and belt configuration.

 

[sld961]

I called Baldor and asked them about this application. They said the motor itself (bearings, etc.) are fine for a pulley application. They don't offer any "feet" that can be field installed on the motor case, and they don't recommend welding anything on the case, because it may damage the windings. So, now I just have to determine if I want to try to fabricate some mount and use the Baldor, or just use the GE. I have very limited fabrication equipment available, short of taking it to a shop.

If I use the Baldor, I can sell the GE to recoup some cost. But if I use the GE, I wouldn't feel comfortable selling the Baldor, because it was given to me.