Changing a motor for a vari speed

I'm in the process of re-commissioning a 3" Russian lathe. Tony Griffith has a page which shows the machine in question here

www.lathes.co.uk/russian/

I haven't used the lathe for several years because of lack of space and the fact that the machine is hard to move, it's heavier than my "big" lathe a Sieg C3 mini lathe. Therein lies my problem, the variable speed on the Sieg is so good to use. The belts and pulleys on the Russian lathe seems so 20th Century. Because the machine is compact the pulley system is also compact and a real pain to use.

The existing motor is 500W and gives a spindle speed range of between 200rpm and 3,200rpm. This speed range is excellent, but the low speed is too high for screwcutting.

So I thought that if the motor could be changed for a variable speed unit and (ideally) if the lower speed could be dropped to say 50rpm a good machine would become terrific. Then if a toothed belt drive was used, the same type used on the C3 would be good from a spares reduction point of view, good but not essential.

So does anyone have any suggestions for a motor/controller system that would be suitable for someone with little or no interest in electronics.

cheers

Bill

ps this is the third time that I've written this, it has disappeared on the previous two occasions, hope it doesn't happen to this one!!

Hi Bill,

I have variable speed on my 290 lathe - a 3-phase induction motor and inverter so I can run it from a single phase supply. I am very pleased with it, I kept the old pulleys and belts so I get a lot of torque at low speed. If you can change the old pulleys to toothed belt pulleys you can get a lower speed than 200 RPM. Whether you want to buy a brushless DC motor and controller or a 3-phase induction motor and inverter, well both should work well. Sieg uses a 500W brushless DC motor and controller on the SX2 MiniMill, I have not used this combination myself so I don't know how difficult it would be to connect it to your lathe. Inverter and 3-phase motor was not difficult to connect, I found instructions on the web.

Thor

Edited By Thor on 25/03/2015 06:50:01

Hi Bill, I go on about this endlessly, but just be aware that when you use any sort of speed control to slow down a motor below its normal running spped, you are also slowing down the motors cooling fan, so be aware of the possibility of overheating. Best way is to use the gears/belts for the slow speeds as much as you can, or arrange an independant cooling fan for your motor.

Phil

UK

My inverter is programmed with the motors parameters and rating and estimates the temperature rise when it is running. It's not foolproof, I imagine, but it does offer more protection than crossing your fingers...

Neil

Variable pulleys? Colin