A couple of questions re servo's

[comet]

Hi and Merry Christmas/happy new year!
firstly I'm doing a bf20 conversion using gecko 320x drives. my x an y are 24 volt and my z is 36 volt.
I have a 36v powersupply and I'm thinking as long as i don't try and run the 24volt servos past there rated rpm at 24 volt I should be OK powering them from the 36 volt power supply?
  Also fat32 or ntfs whats the best for mach? I know audio recording software works better with fat32 because it writes in realtime rather than blocks ala NTFS,would this be an advantage ?
Finally (for now) how have you guys got around the limeted space on the y axis when fitting ballscrews?
   regards
 Tony

[HimyKabibble]

No, I would guess that's probably not a smart thing to do.  The Gecko uses PWM, which means it is switching the full supply voltage on and off to control the RMS (average) current.  Running the Geckos at above rated voltage for the motors would not only leave open the possibility of cooking the motors if the Gecko fails, andI would think it would also be likely to result in the motors running hotter than they would if run within their ratings.  If you want to get a definitive answer, I would contact Gecko tech support directly.

Regards,
Ray L.

[comet]

well my thinking is that rpm and volta\ge are linked and ive checked this ie at 2800 rpm on a gecko the motor is drawing 24 volt

[HimyKabibble]

well my thinking is that rpm and volta\ge are linked and ive checked this ie at 2800 rpm on a gecko the motor is drawing 24 volt

The motor does not "draw" voltage.  Voltage is applied by the driver, at the power supply voltage, and that voltage induces current in the motor windings.  Most motor ratings are determined by thermal limitations.  What you measure with a voltmeter is an average value, but with a PWM drive, like a Gecko, it is the instantaneous values, which CANNOT be measured with a simple meter, that will get you into trouble.

Regards,
Ray L.

[comet]

OK, so ,whats the best way of knocking down my 36v to 24V and still deliver 2 x 6amps @24v ? would a couple of 317 voltage regulators (3amps each) wired in parallel per motor do it?

[HimyKabibble]

Wiring 3-terminal regulators in parallel is not wise.  One will invariably be set to a slightly different voltage than the other, and end up doing most of the work.  The right way to do it is to build a high-current regulator using a pass transistor capable of handling the full load current.  An analog regulator will also be very inefficient, since 1/3 of the energy will be lost as heat in the regulator - you'll need some hefty heat sinks.  You'd really be FAR better off just getting a 24V supply.  Do you NEED the full 36V for the Z axis?  If youi don't need it to go to full rated RPM, run all the motors on 24V.  The only thing you'll lose is top-end speed on the Z axis will be reduced by 33%.

Regards,
Ray L.

[comet]

its ok I have an 18v toroid to make a 24 vold supply just a bit tight for space,can you "stack" toroids phisically not electrically,because i know they can do weird stuff!
Any thoughts on FAT32 vs NTFS ?

    Tony

[HimyKabibble]

I don't think you'd want to stack the toroids without some space (perhaps an inch?) between them.  Either file system should be fine.

Regards,
Ray L.