Breaking in a DC motor?

[crab]

I have my new X1 mill tore down for clean up and was going to break the motor in.I was taught you should run the motor unloaded at low RPM for a few hours to bed the brushes in and minimise arcing on the commutator.The manual says to run it at high RPM for ten minutes in gear.It seems to me that would cause a lot of arcing and pitting on the commutator.What do you think would be the best way to do it?
Thanks,Bill

 

[picclock]

I think I'd be inclined to go with the manual. All your doing is wearing the brushes to the exact shape of the commutator. Arcing is kind of a way of life for these kind of motors, even when run in so its not going to cause problems. However if the brushes are new and you apply a heavy load without bedding in you will create local hot spots where the contact is and that can cause the brush to crack or break, additionally the holder can get very hot and possibly melt.

Hope this helps

Best Regards

picclock

 

[Ken I]

Arcing is not really a problem unloaded - personally I have found running in DC slotcar motors near flat out and unloaded seems to be best for running in.

Typically new brushes are flat faced - if you have the motor apart you can wrap emery around the commutator or make a brush file with a Plug of the same diameter (with a spiggot end to go in the bearing) covered in emery paper - use until full radius is achieved - you can then pretty much forego running in.

By similar method you could put the rad on in a mill.

I wouldn't lose too much sleep over it one way or the other.

Just don't run it under heavy load staight out of the box for the reasons stated by Picclock

Ken

 

[lordedmond]

I used to work a long time ago as a armature and stator winder ( during my apprenticeship )

it was only on the big stuff did we bed in the brushes , by big I mean 75 hp dc up .

this was done while under power on the test bed with a com stone , the small stuff we just let it rip


the main concern for the large stuff was to make sure they would run up to speed as they where used in pipe spinning machines if they were slow the molten iron ran out like a catering wheele

we never had a comm that was not that chocolate colour that we strive for

 

[crab]

Thanks guys.I guess it doesn't matter then as long as it is unloaded.
Bill