So I bought a Sherline, need a motor

[Aaron_W]

An AC/DC motor is a brushed universal motor. It has a rotor that looks like a regular brushed DC motor with a commutator. The magnetic field comes from a windings on the stator (non rotating part).

Things are arranged such that the motor runs the same way on positive AND negative voltage. This comes from the wound stator, whose magnetic field is swapping direction with the positive and negative voltage. The rotor also swaps, but with the right connections, it all comes out right

Reversing them requires reversing the leads on the stator.

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and my understanding is variable speed on these motors comes from running less current so there is a loss of power. My watchmakers lathe has a universal motor and the speed control is just a rheostat foot pedal.

 

[Aaron_W]

I don't know what an ac/dc motor is. The bearings are the same whether it's a lathe of my vintage or a new one? I do believe w/the proper pulley, the current motor can drive the h/s up to 10,000rpm. Could my lathe handle those speeds, not that I want to go anywhere near that high.

Sherline went to the current motor in 1993, so I'd think as long as it isn't older than that it would be fine. There is no warning against using the high speed (10,200rpm) pulleys on older lathes.

Sherline replaced the brass bed with steel in 1982, but without the motor I'm not sure how to determine the age of a lathe made between 1982 and 1993 when they went to the new motor.

 

[skogkatt007]

The sale on headstocks was over by the first of the month. I had in mind to buy the milling column and. Headstock and use it like a Unimat. They run different sales every month which is swell. Shipping from California.is painful though.

 

[Weldingrod1]

Variable speed on universal motors comes from varying the Voltage.

Torque comes from current; controlled/limited by your power supply. This could be mostly the same over a reasonable speed range.

Power output will fall as you slow down. Unlike AC motors on VFDs, there's no constant power range at the upper end.

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