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DC motors?

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Bob Chapman

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I'm looking at a Laguna lathe but I'm doubtful about DC variable speed motors. I've no experience of them and wonder how powerful and reliable they are. Has anyone used a machine with a DC motor for long enough to say?
 

mindthatwhatouch

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Sorry can’t help with lathe experience, as I’m in the same boat (watching with interest as the 18/36 is on my shortlist) which one are you considering?
However, coming from the electrical industry (albeit a while ago) what I can add is that DC motor and speed control technology has improved to a mature state. Overcoming old issues such as lack of low speed torque, unreliable and expensive speed control. Make no bones about it, if they’ve used Permanent magnet dc motor it’s selected because they are cheaper, but more efficient, higher starting torque, quicker to start stop and reverse and easier to control speed.
If motor and speed control are correctly selected by the manufacturer there should be plenty of power, but that’s always the case!

IMHO I’d select the lathe for features rather than an AC or DC motor.
 

Paul Hannaby

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DC motors have high torque even at low speeds whereas AC motors tend to lack torque at low speeds. In reliability terms they are probably similar to AC motors. and commonly available as are DC motor controllers so in 10 years time when the manufacturer say they can't provide spares, you should be able to fix it with a generic unit.

The Nova DVR lathes use a Digital Variable Reluctance motor (like the ones the Poolewood / Silverdrive lathes used to use). Hence the name! These probably aren't easily repaired with a generic unit so when the manufacturer stops supporting them, there will be plenty of anchors available! :) I think this has already happened with some of the older models.
 

Bob Chapman

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Thanks for your replies, they give me the reassurance I wanted. Paul it's likely that in ten years it'll be me who needs fixing! I wonder if a generic unit will be available by then? ☺☺☺
 

NickWelford

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My Robert Sorby lathe has (I believe) a DC motor which has performed well for 30 odd years. No issues at all. It has different pulleys as well as variable speed so that the variable range is different on each pulley and the torque differs also.
 
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