# Micro Lathe Power Problem



## chrisb (Jan 3, 2008)

I have a Cummins Micro lathe whch is smaller than the Minin lathe. To get it to operate , I have to turn it on and off about 8 times before the moter will get power.
I believe that the motor operates on DC so I guess I just change the switch/reostat. Anyone been thru this? It may be still under waranty. If not is there a way to that I can fix it?


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## hawkeye2 (Jan 6, 2008)

If the lathe has a continuously variable speed controled by a knob it runs on DC at about 90 to 100 volts and has a motor of 250 watts (or less). The switch box on the lathe contains the obvious controls and a circuit board and these components will usually fail long before the lathe wears out. In most cases these small lathes come from the same factory in China and parts are interchangable and avaliable from most importers. I would recomend checing your paperwork and contact the importer if it is still under warranty. An entire control assembly including all switches, circuit board, housing, etc. for the 7 x 10/7 x 12 lathes is $133 and the various pieces of that assembly are avaliable individually (I realize you are refering to a smaller lathe than these). Contact these folks for parts:

http://www.littlemachineshop.com/Products/products.php

I have not dealt with them yet however everyone on a mini lathe group I belong to speaks highly of them


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## chrisb (Jan 3, 2008)

Thanks.


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## RimfireJim (Mar 25, 2009)

Is the On/Off switch separate from the speed control? If so, is it the switch you are having to turn on and off 8 times? If so, then it is just the switch that is bad, which isn't surprising. Switches are the #1 failure point on any power tool, even a good one, and these Chinese lathes will have the cheapest possible switch built into them. You should be able to find a replacement unless it is some weird form factor. Check Mouser.com or Digikey.com if you have trouble finding a switch locally. 
I have a Chinese 14" woodworking bandsaw in my shop. The "industrial" pushbutton switch, made to look like a true motor starter control but obviously not built like one, failed after not much use. I replaced it with a simple household wall light switch that is not really rated for the 3/4 HP motor but was what I had on hand, and it was cheap. I didn't really expect it to last very long, but it has outlasted the factory switch many times over. If and when it ever fails, I'll just replace it with another! 

littlemachineshop.com has a switch for your lathe listed at $11.95


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## chrisb (Jan 3, 2008)

The switch is an on off/reostat, Wonder if i can check it with a multi meter without desoldering it?


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## RimfireJim (Mar 25, 2009)

Maybe/probably. If you put an ohmmeter across the two terminals on the rheostat (with power disconnected!!!), you should (likely) have infinite resistance in the off position and then a gradual resistance change as you turn it through the speed range. Depending on the control scheme, the resistance may be high at "Low" and low at "High", or it may be the other way (low/Low, ...). 
I don't have any experience with these mini-lathes, but I've worked with speed controls on sewing machines. Different brands have different control schemes. On some, the switch is open in the "Off" condition, and on others the switch is closed. It depends on the electronic circuitry and logic of the particular machine.


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