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Old 10-25-2020, 05:52 AM
threepiece threepiece is offline
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Default Electric Motor Shaft Repair

I bought this from the scrap yard yesterday, it works as good as it looks, less the shaft. I guess cutting the driving device off was the easiest way for someone to remove the motor. My plan here is to weld a new oversized extension and turn it to size using the motor itself to rotate the shaft on its own axis. I plan to do this on the milling machine with the motor fixed to the table and a tool bit/cutter secured in the spindle.

I have some ideas to resolve some of the issues I expect to encounter such as the 1725 RPM shaft speed and aligning the axis. If anyone has any input please feel free to let us know, I have not done this before.
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With the amount of energy that is being consumed I expect most people on earth should be living in Utopia. And now this?

It started hitting the fan in the 1950's https://m.youtube.com/watch?v=nRnNDkHb0MU

A technologically advanced society would teach their children how to start a fire by rubbing two sticks together before teaching them how to use a lighter.

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Last edited by GWIZ; 10-25-2020 at 07:27 AM. Reason: rotate picture
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  #2  
Old 10-25-2020, 07:21 AM
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I would remove the shaft from the motor add your over size piece and then use a lathe with a four jaw and a steady rest to center the shaft, drill a center hole, remove the steady and and use the tail stock center to finish the shaft.
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Old 10-25-2020, 07:44 AM
threepiece threepiece is offline
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Quote:
Originally Posted by digr View Post
I would remove the shaft from the motor add your over size piece and then use a lathe with a four jaw and a steady rest to center the shaft, drill a center hole, remove the steady and and use the tail stock center to finish the shaft.
Too late!

I might have done that if I didn’t have so many of these Baldor 5 HP motors and I had never done that before. I simply can’t resist trying something new.

I’m letting the shaft cool now. I have outside things to do, I’ll get back to this when dark.
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With the amount of energy that is being consumed I expect most people on earth should be living in Utopia. And now this?

It started hitting the fan in the 1950's https://m.youtube.com/watch?v=nRnNDkHb0MU

A technologically advanced society would teach their children how to start a fire by rubbing two sticks together before teaching them how to use a lighter.

If you are not having fun then you are doing it wrong.
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Old 10-25-2020, 07:51 AM
threepiece threepiece is offline
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I tried grinding the bevel with the motor running, that didn’t work well. The Metabo grinder was had from the scrap yard too.
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With the amount of energy that is being consumed I expect most people on earth should be living in Utopia. And now this?

It started hitting the fan in the 1950's https://m.youtube.com/watch?v=nRnNDkHb0MU

A technologically advanced society would teach their children how to start a fire by rubbing two sticks together before teaching them how to use a lighter.

If you are not having fun then you are doing it wrong.

Last edited by GWIZ; 10-29-2020 at 02:51 AM. Reason: rotate picture
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  #5  
Old 10-25-2020, 08:35 AM
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You didn't remove the rotor from the motor frame ?
So you toasted the bearing, and probably the stator windings.
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  #6  
Old 10-25-2020, 10:52 AM
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I am wondering how you will be able to angle grinder machine the welded on shaft to bring it to the finished dimension that you can slide a bearing over.

Ted's post is the sure way to do it. I have seen that idea with a tinning of solder on both male and female parts, then heat and assemble. Seemed to work on a 10hp. He was making a double ended motor by adding a output shaft to the outside.
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  #7  
Old 10-25-2020, 01:40 PM
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I agree that removing the armature is the correct way to tackle that job. If the bearings don't come off they can be damaged for sure and getting the shaft aligned and machined is obviously something done much more precisely on a lathe--it's not that difficult to pop the armature out and remove the bearings.

One other issue you may encounter is the placement of the keyway. The original armature is balanced as an assembly with the keyway in place. If you don't put it back in the original location you can end up with a bit of vibration that won't go away...
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Old 10-26-2020, 08:25 AM
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"Rotor".... it's a rotor in an a.c. motor.
Armature is in a d.c. motor.

Jeesh.....
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Old 10-26-2020, 10:17 AM
threepiece threepiece is offline
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I may not have bought this motor if I didn't conjure up this repair method. I need a bit of fun from time to time, I saw a good opportunity in this motor to have some. If all works out this motor will go on my secondary air compressor. I use it to enhance my CFM for sandblasting only, I'm not at all concerned about vibration. I would not attempt such a repair on a motor for a surface grinder. If it doesn't work I will have learned a thing or two and I will have more spare parts.

The shaft has two diameters. The drive interface where the pulley is attached is 1.125". The shaft increases in diameter slightly about three inches from the end presumably to facilitate bearing install. I guess the bearing ID is about 1.170.

About damaging the bearing, I don't believe I did at this point weather it be plain or ball type. The paint on the end cap was barely discolored if at all and it seems to run smooth after briefly running the motor. I don't know what type of bearing it has. At worst I may have emptied the contents of an oil impregnated plain bearing if it has one but there is a grease fitting to offset that issue.
__________________
With the amount of energy that is being consumed I expect most people on earth should be living in Utopia. And now this?

It started hitting the fan in the 1950's https://m.youtube.com/watch?v=nRnNDkHb0MU

A technologically advanced society would teach their children how to start a fire by rubbing two sticks together before teaching them how to use a lighter.

If you are not having fun then you are doing it wrong.

Last edited by threepiece; 10-26-2020 at 10:24 AM. Reason: more content
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  #10  
Old 10-27-2020, 08:59 AM
threepiece threepiece is offline
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Aligning the shaft to the machine. I guess we can call this Y axis. Notice the toe clamps on the shaft end and the fine thread jacking screws on the other. This worked out well for aligning.
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__________________
With the amount of energy that is being consumed I expect most people on earth should be living in Utopia. And now this?

It started hitting the fan in the 1950's https://m.youtube.com/watch?v=nRnNDkHb0MU

A technologically advanced society would teach their children how to start a fire by rubbing two sticks together before teaching them how to use a lighter.

If you are not having fun then you are doing it wrong.
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