Thread: Lathe motor question/advice wanted

Glen, changing the pulley gives you access to more torque where high speeds aren’t required. Another factor is by allowing the motor to spin faster for a given spindle speed, the motor’s cooling fan is better able to do its job.

Originally Posted by LanceC

Glen, changing the pulley gives you access to more torque where high speeds aren’t required. Another factor is by allowing the motor to spin faster for a given spindle speed, the motor’s cooling fan is better able to do its job.

So what is the benefiy of allowi g each pulley to start from zero? Any benefit there?

Also, is an AC motor more desirable than a DC?

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There are others more qualified to answer that question, but my understanding is that an AC motor will use a VFD for speed control, which as a combination doesn’t loose torque at lower RPM’s as with a DC motor, so is preferred if you expect to run the motor at low RPM’s.

As to why all pulley ratios go to (near) zero speed... the speed control is for the motor, which is connected to the lathe headstock via a belt which can switch pulleys to alter the range and torque. The motor and speed controller has no idea what pulley ratio is selected, it just speeds up and slows down the motor. A bit like how the accelerator in your manual car has no idea what gear you’re in. It just makes the motor spin faster and slower.

You also need to look at where (actual motor RPM-wise) the motor is delivering it's max power.

When turning a large blank, you generally want lower spindle RPM so the outside diameter of the blank is turning at an acceptable surface speed. By the same token, the larger diameter means more leverage so it's easier to stall the piece with tool pressure/dig-in.

Hence you want max motor power delivered at lower spindle RPM.


On t'other hand, if you're turning pens you want high spindle RPM... the small diameter needs to turn faster for the surface to be travelling at about the same speed. While you don't need as much power for pens per se, if you imagine turning small dia spindles, etc. instead then you DO want the power there.


So... just like the gear-box on a car you use it to put the power in the spindle RPM range that you want.

Really, it's like giving a kid his first geared push-bike. It only takes a bit of trial 'n error to work out what's going on.

To me, I think I would rather start at zero RPM and slowly ramp up to what I need rather than hit the start switch and have instant max speed on whatever pulley you're set on. ............. Jerry (in Tucson)USA

If you are looking for a lathe around that size, then this one from Pop's Shed may be an alternative.

Lathe 14" x 20" Variable Speed #126057 - Woodturning Tools and Timber, Woodturner Accessories, Woodcarver Supplies, Woodturning Equipment

Essentially this is almost identical to the Timbecom unit, look closely. There is one difference I can think of between the Timbecom unit and Pop's unit; lathe speeds. The Pop's Shed unit doesn't start from 0 to whatever on all three speeds, I think the speeds start around 125 on the lowest pulley around 500 on the middle pulley and I cannot remember the high pulley starting speed.

My Men's Shed bought one of these, as did one of our members, for what it is worth, these are quite a reasonable bang for your buck.

At the Shed we generally leave the lathe on the middle belt and it pretty much does most things one needs. If you are turning something heavy and off balanced, then you will need to bolt it down to something; there are four bolt holes. It will handle a 320 to 340mm bowl easy as anything, providing you prepare the blank accordingly.

On the Timbecom unit, the red handles double as tool holders but are primarily lifting handles, the Pop's Shed lathe has grey handles.

There is no bed extension possible for these lathes, which is probably not bad, but I think it would have been a nice addition. Takes Vicmarc VM100 and VM120 chucks with ease, although the Vicmarc 100 chuck is the best size for this sized lathe.

A word of warning with these lathes and chucks, be wary of the top speed of your chuck. Some good value for money chucks have a reasonably restricted top speed, some as low as 2,000 rpm. With these new lathes having very high speeds, it is quite easy to go way over the top of the chuck's maximum speed.

Mick.