# Micro Lathe Pwer Problem



## chrisb (Jan 3, 2008)

About 3 years ago I bought a Micro Lathe at one of the traveling tools sales.
Now to get to run I need to turn it on and off abour 5 times an then it may start turning. 
I believe that the motor is dc.

Is there anyway to by pass all the contols and use a reostat and newafter market power supply?


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## Totalwrecker (Feb 26, 2009)

I've got an old table saw that after turning on I need to spin the blade and then it runs. Sometimes it runs right off, but most times it needs a nudge. 
I think it's a bad spot on the communitator (motor) and not the on/off switch. 

To answer your Q, yes you should be able to rewire to bypass the present controler. But if your condition is like mine, your fix, won't. 
See if your motor starts when you spin the pulley. 

My saw is old and I chose to live with it... 

Happy Holidays 

John


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## hawkeye2 (Jan 6, 2008)

The Little Machine Shop has repair parts and accessories for these lathes and super service too.

http://littlemachineshop.com/produc...?critFast=lathe+control+box&B1=Product+Search


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## SteveC (Jan 2, 2008)

Posted By Totalwrecker on 24 Dec 2012 10:09 AM 
I've got an old table saw that after turning on I need to spin the blade and then it runs. Sometimes it runs right off, but most times it needs a nudge. 
I think it's a bad spot on the communitator (motor) and not the on/off switch. {snip...}[/i] John

Don't know for sure, but it's likely that your saw motor is a capacitor start type, if so it will have a big metal bump on the outside. The capacitor serves to ensure the motor starts up in the desired direction and has the torque to start running. If the capacitor goes bad (i.e. open I believe) then you loose the torque to start and you can make it run in either direction by manually spinning it one direction or the other. All you may need to do is replace the capacitor. Just a thought.


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## Michael Glavin (Jan 2, 2009)

Chris
What brand micro-lathe? Depending on the brand they are either AC or DC, with many variables of motor type…

Since you noted it was likely DC, is it a Sherline Lathe? Sherline uses a 90V DC electronic speed control, which is a non-proprietary component available online generically (if I recall around $60.00). Older Sherlines used AC/DC motors.

AC capacitor start motors generally have a start switch either mechanical or electronic. For the most part mechanical switches are generally in play; these are centrifugal switches that unlatch a set of points or contacts when the motor spins up to operating speed. Common problems with mechanical switches are the contacts stick closed, the resulting behavior emits an unusual noise and or the switched contacts don’t close which sounds like your description (spins up lazily).

A failed start capacitor also sounds like the open contact failure mode and your description. FWIW the start capacitors are pretty durable. In my line of work I find the switches are the most common failure mode.

Michael


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## JPCaputo (Jul 26, 2009)

For harbor freight micro lathes 4"x5" it is a 90vdc motor. I have been having trouble with it too. I know it is the on/off/speed control knob. The pot or switch behind it is probably going bad. Or bad solder/crimps in the wiring. The speed controller that is mounted beneath. 

Also the e-stop switch may need cleaning.


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