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South Bend 9" Motor Repair/ Replacement

SlugChucker

Plastic
Joined
Feb 6, 2020
Hi All,
I'm new to this forum. I am a hobby machinist but this is about a lathe I'm trying to fix for a friend. He has a South Bend 9" with a fast reversing single phase 230v motor. The start run relay is faulty. Usual fault, run contact arc damaged and coil neutral melted into housing. Relay part: General Electric 5099122 BE2. I've done my due diligence and note that the relay appears impossible to get. Does anybody know the start and run currents for a South Bend utilising 230v 1/2hp motor with 1435 rpm. The motor currently fitted is a General Electric 5KC63AB821. The reason I'm looking for the winding currents is that I'm hoping to use a Klixon current type motor starter instead of the GE relay. Has anybody replaced the fast reversing motors with a modern alternative?
If there is a replacement motor out there would you have a part number handy?
If there is no alternative motors out there is there a way to bypass the faulty relay and just leave her as a plain start run capacitor motor. Motor to relay wire colours:
Black - relay common
Green -N/C
Yellow + coil - N/O
Red - coil
Are green & yellow the run winding?
Thanks in advance for any assistance given.
Cheers,
Slug
 
You are going to be way further ahead replacing the motor with modern equivalent motor either new or used. Everything you need to spec another motor is on the nameplate of the old motor I bet the amperage draw is on there too. Just make sure the motor shaft size will work with the pulley that is with it. South bend used a oddball pulley on the motor. 1435 RMP seems slow is it set up for 50Hz power?

:Edit: I see you are in Ireland you do have 50 Hz
 
As the previous poster stated, you're being a bit myopic. You should consider that this lathe is quite light and not very stiff. Consequently, any tool load fluctuation will cause some tool deflection. Single phase motors under load suffer speed modulation and slow down and speed up during a single revolution in time with the power line frequency. This causes minute tool deflection which will show up as a herringbone finish in high gear on a final light cut finish pass. By going to a 3 phase motor, the magnetic pulses are much smoother and this issue completely disappears. In light of this issue and the fact that the old motor has failed, it is a golden opportunity to replace the old motor with a VFD and a 3 phase motor.
 
This causes minute tool deflection which will show up as a herringbone finish in high gear on a final light cut finish pass. By going to a 3 phase motor, the magnetic pulses are much smoother and this issue completely disappears.

Interesting!
 
Many thanks for all the replies, we replaced the motor with a new single phase unit. A little bit of work will be required to get it to fit but that's not my end of this job. I was only looking after the electrical.
As for "being a bit myopic", na not really. It's not my money, not my machine and this guy doesn't want to change anything. The motor we got will do him grand, down 100 rpm up a 1/4 HP so swings and roundabouts.
He's happy and that's all that matters to me. The wiring and control is now all modernised with off the shelf parts and well uprated to last a lifetime.
Again thanks for your input :)
Cheers,
Slug
 








 
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