Wrong Frame Size On Replacement Motor

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Fender
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Wrong Frame Size On Replacement Motor

Post by Fender » Fri Oct 03, 2008 7:47 pm

The table feed motor (3 phase) on my milling machine was burned out when I got the mill. I had an available motor of suitable hp and shaft diameter, but it was the wrong frame size (FM56C vs. 56) and is a flange mount motor. I could have bought a different motor but instead I came up with this "field modification". I disassembled the bad motor and sawed off the mounting base. Then I attached the new motor to the original base using hose clamps. See attached photos.
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ButcheredMotor.jpg
ModifiedMotorB.jpg
Dan Watson

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Bill Shields
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Field Modification

Post by Bill Shields » Fri Oct 03, 2008 9:53 pm

now there's a man after my own heart!

Nothing like hose clamps around a shop

:shock:

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steamin10
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Post by steamin10 » Fri Oct 03, 2008 11:16 pm

UHn - Uh. Nice try but I wouldnt run that on a bet. I might C- clampp the pad and tck weld it to the C-frame, gut consider this, all the torque on the motor is gonna be on those poor clamps, It will move, adn over time, what if.. Ya need to make that a litte more stable. Plus whats about the coupling linup. being off very far is diasaster for a coupling, and bad for bearings..
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

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Fender
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Post by Fender » Sat Oct 04, 2008 8:09 am

Steamin10
I calculated the torque of this motor and it comes out to only about 1.5 ft-lbs of torque at full load. This isn't much force on the bands (about 6 lbs at 3" radius from the center line of the motor shaft). But at the same time, it uses a belt drive, which will put a larger lateral force on the motor shaft and therefore, the clamps. So, I'm inclined to agree about spot welding the base to the motor.
Thanks,
Dan Watson

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steamin10
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Post by steamin10 » Sat Oct 04, 2008 10:27 am

It is more work but you seem willing... Take the motor plat to the drll press and drill out the spot welds.They are hard @ssed plug welds but 5/15 drill will make them go away. Then the important dimension is from shaft end to the first mounting hole. Set motor case on base and measure with square @ motor shaft end, setup your critical base dimension,and tack the base. Once stable, plug weld the base thru the drilled holes, two stitches front and back of the base and you are good to go. 'Finger paint' the welds for rust and go.

Good reference books have base dimensions for common motor frames, so this would be good to work from, to eliminate drift. Otherwise it is best guess on physical setup.

Have adapted motors for various jobs,with mixed to good success. Mostly to trim $ from temporary projects. Keep your welds small and hot for good pen, but dont dalley,th heat will go into the case. I have never ruined a motor from the welding, and have saved many a motor that was knocked off equipment by cranedrivers, and kamakazee forklifts.

Good Luck.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

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