Lathes with speed controlled by reducing motor speed have a lot less torque at low speed than ones with mechanical speed reduction so a more powerful motor is going to be better for low speed use.

The noise will depend on what you are doing. Turn a bit of square steel bar down to round and you will make a lot of noise because of the intermittent cut. Turn a round bar of aluminium and I would expect very little noise. Milling is generally more noisy than turning so if you decide to use the lathe for milling then there will be some noise probably between the two examples above.

Martin

Lathes using DC motors with speed control sem to keep blowing controller boards. Doesn't the WM240 have a 3 phase induction motor + VFD? Generally a higher power system may be less prone to blowing power devices under the same load so I'd go for that one.

Buying a machine does not necessarily mean you have to stick with that particular motor forever, I replaced my 750W DC motor with an AC + VFD equivilent on a Warco WM16.

I would say my past experience with motors has generally favoured single phase and 3 phase /w VFD setup, never had a failure to date whereas i've had 2 DC motors go kapputt for multiple reasons handling the same circumstances and workload,

that could be because i managed to miss all the nice quality DC motors such as parvalux? who knows, but thats how it's played out for me.

I'm not critical of DC full stop, they do have some very good applications but being the main driver of a powerful machine and cutting strong materials hasn't worked out for me so far, maybe i'd have needed brushless drives or a much bigger DC current to make that a reality.  So far i'm happy with the AC ones though. 

I will find out in the future because i'm planning to resurrect my CNC sherline mill with a far better brushless DC motor and drive. So i'll get my verdict, i'm hoping for positives this time round! 

Michael W

Edited By Michael Walters on 09/11/2016 12:32:36

It's not strictly true that variable speed lathes lose torque at low speeds, the torque is actually constant.

What they don''t benefit from is the increase in torque generated by gearing down a constant speed motor.

With a decent sized motor this isn't as much of an issue as often supposed.

Finally more modern DC speed controllers are generally more reliable and the brushless DC ones seem tobe particularly reliable.

Neil

Sorry Martin, I misinterpreted your post.

Neil

If the torque stays the same as the rpm reduces, the hp reduces. simply torque and revs is horse power. With a belt head or geared lathe, as the speed is reduced the torque goes up.

Ian S C

It's pretty obvious that the op should go for the higher power lathe in this case and also get the plus of the accuracy report. By the time the kit is added to the other one may well work out to be more expensive. People may think that they will never need the kit but chances are that they will at some point.

These lathes often have 2 speed ranges and some people run them in the lower speed range most of the time. They do keep playing around with the speed ranges though and it may be that the max speed in the low range isn't as convenient as it was. They do this to allow very low speed screw cutting.

The Warco also seems to weigh more. Probably due to the extra bits and pieces.

I don't think that you will find noise levels a problem. If the lathe used gears for the spindle drive you probably would unless it was all rather carefully made. My machines are in the house and it hasn't caused me a problem even after fitting an inverter to my lathe which made it noisier than it was before.

John

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