Craftsman 12" Lathe Will Not Start Without "Help"

B

btvarner

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Oct 2, 2019
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Machine:
Craftsman 12" Metal Lathe, Model 101.07403, Craftsman 1/2 HP Motor, Model 115.6962

Overview:
Just purchased lathe. I saw it work fine at purchase. Removed motor to lighten load so it could be carried downstairs. Finished building an mounting the lathe on a new bench. Tested motor on the bench. Works fine. Successfully wired in a drum reversing switch.

Issue:
When switched on the motor hums but most of the time does not start. Quickly "helping" the motor by starting to spin the pulley immediately starts the lathe up. Lathe runs fine until shut off again. Which requires the same assistance to turn.

As I said, the lathe is oiled and worked fine before removing and re-installing the motor. I am new to lathes. Need ideas as to what the issue might be. I have not comparison knowledge to know if the manual turning of the lathe pulleys and gears for this lathe is too tight or not. Any ideas where I might check for binding in the lathe headstock? I have adjusted the tension on the motor belt and that makes no difference. Motor does not spin in the belt. Rather does not spin at all without help.

Note that when I initially put the motor on last night and tested, most of the time the lathe started on its own about 80% of the time. This morning it will not start at all without "help"

Thanks!
 
Hi BT, like Latin mentioned it could be the start capacitor or it could be a loose wire in the starting circuit, open start winding, or even a breakdown in the motor centrifugal start switch. But the capacitor is the most likely suspect if it's old
Mark
 
Last edited:
Thought that might be suspect. I will go ahead and see if I can find a replacement for this motor. Will let you know...........
 
Ok, a quick look on the internet produced no options for a capacitor for this motor. Any ideas where to buy?
 
The info should be printed onto the capacitor and what your looking for is the microfarad (sp?) Shown with either Uf or MFD following the numbers And the voltage it runs on usually indicated as vac....These NEED to match whereas the size and shape only matter when it comes to fitting back into the stock space. Grainger, Amazon, ebay all should have what you need.
 
btvarner said:
I will go ahead and see if I can find a replacement for this motor.
Click to expand...

If it is a single-phase AC motor with a reversing switch, it either has a capacitor OR a secondary winding that
gives it its direction. The drum switch wiring should be double-checked; the 'hums but does not start' means
that the secondary winding's wiring is not making contact.
 
The Craftsman motors of yore used a "flat pack" capacitor mounted in the base of the motor. You will find it very difficult, if not impossible, to find a direct replacement. Hanging an external cap is no big deal, but gets into some cute wire routing and insulation.

I have some that have external caps mounted, some I just swapped the motor. Using a Baldor "farm duty" because I like those motors. NEMA 56, reversable, 5/8" shaft. The original pulley will not fit, you'll need to make one or do as I did and use a different one. (101.27440 12X36) Same as your's but with a Q/C gear box installed.

There is a possibility that the start switch has failed, but you have to open the motor to get to it. A problem on new motors, a disaster on old ones with cloth covered insulation. Check the cap first, replacing it with a new one. The starter switch is an internal centrifugal switch that is closed at rest, opens above 50% (m/l) speed. It is easy to repair, but you must disassemble the back of the motor to get to it. Like I said, not so easy.

.
 
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