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Question about lathe stalling

ecdez

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#1
I have a South Bend 11 with what appears to be the original 1/2hp Westinghouse motor wired for 220v. I was taking a cut and it seemed to stall the spindle rather easily so I looked into the flat belt to see if it was slipping and it wasn't so I checked the V belt too and it wasn't slipping either. The electric motor is actually stopping. I pulled the motor and checked the brushes and everything seem fine, oiled it up and rotated by hand and there's no binding so I threw it back in and no change.

I'm no lathe expert but I don't think I should be able to stop the motor by grabbing the lathe chuck by hand. Am I wrong?

This lathe is new to me so not enough experience to see it go from bad to worse.
 

Asm109

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#2
I have a SB 10 inch lathe with a 1/2 hp 3 phase motor. It will take .1 inch depths of cuts in mild steel without slowing down.

Sounds like your motor is buggered
 

woodchucker

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#3
There are no brushes in a 220V AC motor.
For a single phase you have capacitors, and some motors have both start and run capacitors.
I suspect your caps are bad. Or you are wired for 110 rather than 220, on a 220 motor.. that would also lead to a weak motor.
 

markba633csi

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#4
Can you post a pic of this motor? It sounds like the wrong type of motor to be using if it indeed has brushes
Mark
 

ecdez

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#5
It does indeed have brushes, 4 of them. It's a 110/220 motor and I have it wired for 220 which is how they wired it where I got it from.

I'll post some pics in the morning.

The wiring tag says 1 phase (single phase) and it has 9 wires coming out of it. 6 are paired off and attached to each other for 3 groups of two and the other three go to power. The tag says T1, T2 and T3 are used for forward and reverse but does not show 110 vs 220 wiring.
 

Ken from ontario

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#6
I don't know much about wiring a motor but I've had a similar experience with a motor that would run but had no torque, long story short the problem was wrong wiring for 220v, once corrected, it ran with tons of power, have an electrician look at the way your motor is wired.
 

f350ca

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#7
It probably is a repulsive/inductive motor. They produce high starting torque with much lower inrush current than a capacitor start one. Great motors. From what I understand they were developed for elevators in their day. When the motor comes to speed the brushes lift off the commutator (in most cases) at that time the segments of the commutator are shorted together. If the shorting mechanism isn't working I expect it wouldn't produce much torque.

Greg
 

Technical Ted

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#8
It probably is a repulsive/inductive motor. They produce high starting torque with much lower inrush current than a capacitor start one. Great motors. From what I understand they were developed for elevators in their day. When the motor comes to speed the brushes lift off the commutator (in most cases) at that time the segments of the commutator are shorted together. If the shorting mechanism isn't working I expect it wouldn't produce much torque.

Greg
Yes, I agree that repulsive motors have 4 brushes and are single phase. I have a 1HP Westinghouse ARS motor in my B&S milling machine. I recently had to make/replace one of the bronze bushings in it because the rotor what hitting the stator. I suggest when you post pictures that you include the motor name plate and any internal pictures you might have, including the wiring. All of these will help everyone get a better idea of how to help you. Brand name and model of motor helps big time!

Ted
 

ecdez

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#9
Here's some pictures. Looks like it is a repulsive/inductive motor. Popped the end cap off and maybe it's me but it appears something is missing.

20171017_081410.jpg 20171017_081449.jpg 20171017_082150.jpg 20171017_082156.jpg


The following pictures are from the Vintage Machinery site.

Mine does not have this on the commutator end of the motor.





Mine does have a groove on the shaft, possibly for this snap ring.




It appears my motor is missing this whole assembly :confused:.





I'm surprised the motor moved at all considering this is what's used to get it going.



All things considered, I did only pay $100 for the lathe so I guess I shouldn't complain too loudly.
 
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4gsr

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#10
Pull that motor and put aside for historical thoughts and get you a new or used 3/4-1 HP 56 frame motor to take its place. May have to make a mounting plate to adapt the newer 56 frame motor to the old, old, frame motor.
 

f350ca

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#11
That missing part is what shorts out the commutator to allow the motor to run as an induction motor once its up to speed. It looks like yours doesn't lift the brushes when it reaches operating speed. So it can continue to run as a repulsive motor as the commutator never gets shorted.

Greg
 

Technical Ted

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#12
The picture of the nameplate is a little washed out from light. Does that tag say type "CU"? It's also odd that the tag tells what leads to change for rotation, but not for using either 110 or 220 volts??? There are a lot of different configurations for these old Westinghouse motors. My ARS repulsive motor did not have a shorting mechanism. Maybe that's the difference between a type AR and ARS??? Not sure, but interesting none the less.

So far, I have not been able to locate any info on a type "CU" Westinghouse motor, but I am interested in these older devices and will continue to look when I have time.

In the end, if you do end up replacing the motor, you may want to change your pulley size if you want to keep the speeds the same since this is a 1140 RPM motor. I had to replace the motor on my South Bend a few months back and found a great deal on a 1-1/2 HP at Surplus Center. Shipping seems high but the price was dirt cheap and it is a very nice motor. So, overall, the price was very good for what I got.

Good luck,
Ted
 

ecdez

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#13
The tag does say CU, sorry about the light. I was thinking about the pulley size too but the one that's one the motor is very small, maybe only 2 1/2". I imagine I can go down a little but not much.

I dug through my stash and found 3 motors. One is 3400rpm so it's out.

The second is below. It's 120/240 but no plate to show how to wire it for each. The switch on the side only switches one wire and there's only two wires coming out of the box so I guessed it was wired for 120 so I hooked it up and it came right on. I'd rather 240 so I could use the existing wiring in the lathe but no clue how to wire the motor for that. It's also not a reversible motor but I think I could live without that. I can't think of a single time I ran my smaller lathe backwards. Good to know I have a good motor for something else when the need arises.

20171017_113129.jpg 20171017_113153.jpg




The third motor I have is also a repulsive/inductive motor. I had no idea I had it. Anyway, it's also 120/240 and again only 2 wires coming out so I guessed 120 and wired it up. It came on and I could hear the switch when it came up to speed. Pretty cool. There's only 4 wires coming into the box. Wish I knew more about motor windings and stuff like that. Regardless, this one spins the wrong way so can't use it on the lathe but I have a power hacksaw that the motor just went out on so maybe it'll live there. Would be nice to verify it's actually wired for 120 before I use it long term though. Anyone know a good way to do that?

Looks like I'm in the market for a motor :(.


20171017_121306.jpg 20171017_121321.jpg 20171017_121343.jpg
 

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f350ca

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#14
Interesting stuff, Did some more reading and your right Ted some don't short the commutator. They're a repulsion inductive motor, the repulsion windings stay energized but produce very little torque at synchronous speed, there is a second winding on the armature that makes it a squirrel cage motor producing the majority of the torque at speed.
The repulsive start / induction run that Im more familiar with short the only winding on the rotor.
As far as reversing a repulsive start motor I understand its done by moving the brushes around the commutator.

Greg
 

ecdez

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#15
Interesting, the motor from the lathe had a tapped hole at every 90ยบ so the plate that holds the brushes could be indexed. The plate only had one hole to bolt through. Looks like it could be indexed possibly to change direction.

The century motor (the one that's spinning the wrong way for me) has a bolt on the exterior of the motor that connects to the plate that holds the brushes and it's at the far end of a slot that goes about 1/6 the way around the motor. Maybe this slot is for adjusting the placement for reverse direction. It's still on the bench so maybe I'll loosen the bolt and play with it a little.
 

Technical Ted

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#17
Interesting stuff, Did some more reading and your right Ted some don't short the commutator. They're a repulsion inductive motor, the repulsion windings stay energized but produce very little torque at synchronous speed, there is a second winding on the armature that makes it a squirrel cage motor producing the majority of the torque at speed.
The repulsive start / induction run that Im more familiar with short the only winding on the rotor.
As far as reversing a repulsive start motor I understand its done by moving the brushes around the commutator.

Greg
My ARS motor reverses as you describe. The ring that the four brush holders mounts to has index marks on it and to reverse direction you loosen a locking screw and rotate the ring to the other index mark.

Ted
 

markba633csi

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#18
The Scot motor looks like it could be reversed if you did a little detective work on the windings- does it have a capacitor?
Anyhow it looks like you have several options there
Mark S.
 

f350ca

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#19
I have a 2 maybe 3 hp repulsive start motor on my shaper, (no tags so Im guessing) the brushes on it can be moved to reverse it.
IMG_1867.jpg
I was given a smaller one, will have to look closer now maybe its repulsive/induction. I think it was on a gas pump, it has a sealed switch on the end with a lever to turn it on. I wanted to use it on an old Delta Milwaukee metal cutting bandsaw I restored but it turns the wrong way and the brush mounts are cast into the end cap so I couldn't get it to reverse.

Greg
 

whitmore

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#20
Here's some pictures.
Isn't one of those four carbon brushes rather... short?
Could it be that there is just a bad contact from the worn-down brush? Or, maybe it's stuck
(the spring doesn't make it slide freely, maybe grit in the sleeve).

A modern motor, though, would be a bit more efficient than that old 'un. I'd look into used
motors before going on a search for replacement carbon brushes.
 

kvt

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#21
Question I have is did the old motors not have more power than current ones. Even though the old ones that came on them may have only been 1/4 HP it prob worked as good as a 1/2 or better today. .
 

ecdez

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#22
Isn't one of those four carbon brushes rather... short?
Could it be that there is just a bad contact from the worn-down brush? Or, maybe it's stuck
(the spring doesn't make it slide freely, maybe grit in the sleeve).
They're all about the same length and move freely. They just look odd in the picture. When mounted they only stick out about 1/8" from the bottom before they hit the commutator.


Question I have is did the old motors not have more power than current ones. Even though the old ones that came on them may have only been 1/4 HP it prob worked as good as a 1/2 or better today. .
I was wondering the same thing. Or maybe even different ratings for different companies. I was looking at a chop saw and it said it was 5hp but the motor was tiny and I couldn't believe it. When I looked closer it said "unloaded" very small beside the hp rating. I took that to mean it had 5 hp when it was free spinning but as soon as it hit some resistance it probably dropped to 1/4 hp.

The old Century motor is only 1/2hp by the tag but the motor is large and heavy and probably has way more torque than a newer smaller 1/2 hp motor. Just like the machines; I prefer to default to the older stuff first and consider a new one a compromise.
 

ecdez

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#23
Made the adjustment per the manual and now it runs in the direction I need it to. I also read that the end caps could be rotated so the motor can be mounted upside down and the oil cups will still face up. I was going to try it anyway but the manual said it was a design feature.

Final thing to figure out is the wiring. The individual wires are not labeled A-D like the manual shows but they are in a linear pattern. I think I'm gonna go for it and see what happens. The manual makes it look a certain way so I think I'm gonna try it the way it's shown and hope for the best.
 

ecdez

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#24
Well, to close the loop I got it working and installed. Much better than the last motor. Thanks for all the input!
 
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