# Resistance Start- Induction Run Motor



## turnitupper (Dec 31, 2015)

I have a 1/3 hp resistance start-induction run 240V motor from a treadmill that I wish to put on a cheap drill press to replace the POS 1/4 hp on it.
As I intend to use it for tapping, I will use a 3p-dt to switch the start windings to reverse. The only trouble is I was told that constant stop-starts would overheat the start windings.
If this is true would a motor start capacitor in series with the start windings be of any use or sheer folly.
Any advice from the electric motor wizz kids out there will be greatly appreicated.
Thanks 
             John


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## John Hasler (Dec 31, 2015)

Adding a capacitor won't help.


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## turnitupper (Dec 31, 2015)

John Hasler said:


> Adding a capacitor won't help.


Thanks John, 
I had been told that but was not told why. I am like the expired moggie, curious.
Could this motor be used as is because I have already bored the pulley for the larger shaft and fitted new bearings (cart before horse).


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## Wireaddict (Jan 5, 2016)

I suspect a cap would draw even more current through the start winding & also the resistor if it's in series with it causing still more heating.  Also, the cap, by increasing starting current, would also raise the starting torque & may well break taps.


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## turnitupper (Jan 5, 2016)

Wireaddict said:


> I suspect a cap would draw even more current through the start winding & also the resistor if it's in series with it causing still more heating.  Also, the cap, by increasing starting current, would also raise the starting torque & may well break taps.


Wireaddict, thanks for the reply.
There is is no physical resistor as such in the motor.
The resistance comes from the start windings themselves to create the phase shift to start the motor. A centrifugal switch cuts power to the start windings when the motor is up to speed.
Would this motor be suitable for the DP (unmodified) without using it for tapping as I am led to believe this type of motor has poor starting torque compared to a cap. start motor although this motor was off a treadmill with a variable pulley for speed control.
Anything would be better than the original which would stall if it just smelled a 3/8" drill in the vicinity.
Has anyone had any experience with these Resistance start motors?.
Couple of pics,
John.


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## kingmt01 (Jan 5, 2016)

I'm not going to say you can't because I really don't know. I've been following this thread hoping to learn something. But I have seen that induction motors would not be a good choice for this. They are more suited to something like running a fan.


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## John Hasler (Jan 5, 2016)

turnitupper said:


> Thanks John,
> I had been told that but was not told why. I am like the expired moggie, curious.
> Could this motor be used as is because I have already bored the pulley for the larger shaft and fitted new bearings (cart before horse).


Adding a capacitor in series with the start winding would reduce the current in the start winding and reduce the starting torque.

There really isn't anything you can do to improve it.


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## turnitupper (Jan 5, 2016)

John Hasler said:


> Adding a capacitor in series with the start winding would reduce the current in the start winding and reduce the starting torque.
> 
> There really isn't anything you can do to improve it.


BUGGER!


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## f350ca (Jan 5, 2016)

You had me confused with the term resistance start, over here they're called split phase. Common on low starting torque applications. I would say it should work fine on a drill press as is, there's little or no load on start. As for tapping it would probably work, may have trouble if you stop the motor with the tap buried and try to restart in forward, but backing it out shouldn't be an issue. If you were stopping and starting it over and over all day long the you may heat the windings but I doubt it.

Greg


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## turnitupper (Jan 6, 2016)

f350ca said:


> You had me confused with the term resistance start, over here they're called split phase. Common on low starting torque applications. I would say it should work fine on a drill press as is, there's little or no load on start. As for tapping it would probably work, may have trouble if you stop the motor with the tap buried and try to restart in forward, but backing it out shouldn't be an issue. If you were stopping and starting it over and over all day long the you may heat the windings but I doubt it.
> 
> Greg


Thanks Greg.
I will be using it rarely, if ever, to do a production run of tapping so I will "suck it and see" how it works in my tiny shop. I was a plumber/builder in a previous life and as such have had little learning (a dangerous thing , A. Pope) about motors. I can put a thermostatic cut out directly on the start windings if necessary as there is ample room.
Your observation about it requiring less torque to back out a tap is sensible.
After checking the name plate (see photo) I realised it is a 1/2 Hp. 
Thank you all for your input.
PS i am still going to try a small capacitor on the start winding, Never die wondering.
John.


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## amuller (Jan 26, 2016)

I've played around with adding a start capacitor to such a resistance-split-phase motor.  I don't recall the exact details and results, but it seemed to help, by reducing the current through the start winding and increasing the phase shift.  Your mileage .... Of course, once the motor is up to speed and the cent switch open, it makes no difference.  I happen to have a split-phase motor on my drill press because it was handy at the time.  On a couple of very cold mornings it's been unable to come up to speed and the start winding would likely have burnt out if I hadn't shut it down.  On the other hand, adding a run capacitor can sometimes noticeably improve the performance of a motor and may salvage a marginal installation.  Overall, I think this sort of tinkering is better done on a capacitor-start motor because the start windings are more robust.

Alan


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## Smithdoor (Jan 26, 2016)

This type of motor does work on a drill press
I have use a cooler motor on my mill it has two speeds work great in my small shop
If I some one was using all day long I would use a cap start motor with SF of at less 1.15
Some motor are not wire for Reverse this can be done just find the two wire use the start (The smallest wire in the motor winding) just use for your reversing switch by switch them .

Dave


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