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single phase motors.

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Is there anything on the site about how to fit a reversing switch to a single phase mains motor ?

I need to make my lathe go in reverse for screw cutting. I'm using a 1 HP motor as bought from Machine Mart.


You can get a switch from ebay that comes with detailed instructions

Not sure if machine mart do one or not

Essentially, the start/run capacitor is switched between the live and neutral - its other terminal is connected to the start winding.

On a motor with a start only capacitor (these usually have centrifugal switch to disengage the cap once the motor is spinning), it's usually necessary to stop the motor and restart in the reverse direction. Motors with continuous start/run caps, ( often small motors) the motor will reverse as the cap is switched.


John,  Bill,

I'll be ordering one of those switches tomorrow.  It will certainly be better than moving the saddle back along the bed by hauling on the belt.


I've always wondered about lathes that have a separate rack (as my Craftsman does) besides the lead screw and half nut and no tumbler reverse. Why the rack at all?

My Gingery lathe had no reverse, but it also had no rack so releasing the half nut released the slide to be positioned as easily as the tailstock is -- just slide it to where you want it. In fine adjustments or screw cutting without the indicator (not that I had made change gears yet) you could just release the motor drive and rotate the lead screw backwards with a ball handle at the end of the screw. It was very simple and very fast to work with.

I find the rack and wheel on the Craftsman clumsy -- fair amount of backlash -- very coarse adjustment virtually requiring a additional lathe stop or gauging setup to cut to a dimension, and slow to traverse the carriage compared to releasing it and sliding by hand. I can see the need for something like that on an industrial size lathe where the carriage is massive and needs a handwheel to budge it or the bed is very long. But on a small home workshop lathe? Perhaps it's just a bit of sales appeal to look like the big boys. Apologies if I'm missing something...


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