Variable Speed - a cautionary tale.

[tekno.mage]

I'm surprised that your eletronic variable speed lathe came up to 3200 revs quickly enough for you not to notice before harm was done. One of the things I find extremely annoying about some of the modern lathes is the time they take to both come up to speed and also to run down and stop. The old Vicmarc which I also use is much more user friendly - it comes up to speed fairly quickly (ie not so slowly as to be annoying) and runs down at a sensible rate plus allowing you to grab the handwheel and slow it down even quicker if required (ie the hand wheel doesn't fight back as it does on the modern Record Power and Axminster lathes I've used). I know - I could probably re-programme the inverters to correct this but life's too short to read the 300 page manual written in poorly translated english to find out what parameters to change and how to do it!

 

[woodfarmer]

There is another thing to watch for.

When you switch off the power there is quite a lot of charge left in the capacitors. If you push the start button soon (read near immediately) after switching off pushing the start button will result in the spindle jogging for about a revolution. (Applies to my Axminsters 1628 VS). Could wind up the pain levels somewhat if you had a finger in an unfortunate place.

Most people would assume that with the power off there is no power available for the motor so the thing is dead and wont/cant go. The variable speed system basically converts the incoming mains to DC which is stored in the capacitors and the electronics switches power on and off the three phase windings, varying the frequency to vary the motors speed. so for a short while the electronics have enough stored power in the capacitors to run the motor even with mains power cut off.

So pulling the plug does NOT make it safe (quickly).

 

[Grahamshed]

<raises eyebrows and nods head with sideways deflection ?
Hmmm. OK. Duly noted.