Variac

[MCB]

I've  been offered a Variac by a chum who is  clearing his shed

Can I  use that to control the speed on my lathe?

It's rated at a couple of Kilowatts so much higher than the lathe.

Thank you for taking the time to respond.
 
MC

[Bryan Milham]

MC,

It's been a long time since I've used a Variac bit I seem to recall they work with DC motors.

I am of course prepared to be wrong on this point.

[Andy Coates]

A Variac (variable AC) is used to reduce AC voltage. So you might run UK rated equipment and US equipment for instance.

An electronic variable speed controller converts AC single phase to three phase and it is the 3 phase that provides the functionality of variable speed.


So in short, no. You cant use it as a variable speed controller for your lathe.

[Paul Hannaby]

the variable speed controllers work by varying the frequency, not the voltage so a variac won't help unless you are going to use a DC motor.

[MCB]

This may be a naive question but if a Variac can't be used to vary lathe speed, what can it be used for (other than as a VERY heavy doorstop)?

Very many thanks for your  helpful comments

MC

[YewTube]

A Variac is a variable transformer. It can be used circumstance where the voltage needs to be decreased.

It can be used to control the speed of Universal motors where the speed is dependant on the voltage. A Universal motor will run on either AC or DC. Electric hand drills with brushes are Universal motors. The Variac will control the speed of these types of drill.

Bill