trying to get definitive on PS requirements

[stirling]

Hi - I'm new to the zone and am currently in a couple of threads trying to nail my understanding of PS requirements, but as I use gecko 201s I finally found this sub forum and so here goes.

I currently run four 2.8A motors successfully from a 6.5A supply but I'm wondering if I can take that down even further. I'm thinking (4 x 2.8)/3 = 3.73 or lets say 4A.

This would certainly take the cost of building the supply down - any advice gratefully received.

[stirling]

No takers then? OK I'll put it another way after reading various threads about hot steppers and how they should be that way.

I get the fastest rapids that Mach3 can give me on my PC - 15m/min. At this speed motors are doing 2500 (full) or 25000 (micro) steps/sec.
I have more than enough thrust on each axis and I get an accel that seems to let CV do it's stuff at cutting speeds of around 3m/min (fast enough for the spindle power I'm using at the moment). All luvly jubly. Yet - the motors hardly get past luke warm.

PS is 60Vdc 10.5Amax. drives are gecko201s correctly current set. The four motors are NEMA23 1.8Nm (260 oz/in) 3.3V 2.8A. Soooooooo,

what have I overspeced? the motors are hardly animals.
Is 60V way higher than I need? But then reducing it isn't likely to cause motor heating (is it?) Seems a strange question to ask but how do I get these things to show a little willing and run hotter?

[Oldmanandhistoy]

Hi,

You are correct to calculate the Amps rating of your PSU at two thirds of the total rating of your stepper motors.

Decreasing the voltage will reduce the amount of torque your stepper motor will deliver as speed increases. Reducing Voltage will decrease motor heating.

Are you using current reducing when idol setting on your drives (don’t actually know if Gecko’s have this feature but would be surprised if it didn’t)?

Are the stepper motors fixed directly to either an aluminium or steel frame which would work as heat sinks?

If everything works don’t try to fix it.

John

[stirling]

Hi

Sorry, I should have also said that they are 4 wire motors and therefore from gecko's docs I only need 1/3 which is why I'm doing 4*2.8/3 = 3.73 i.e ~4A

Thing is on this particular machine I have a 60Vdc 10.5A PS - if next time I build I could get away with let's say 4A at 40V for no loss it would save me quite a bit of dosh. (Still don't see how this will heat the motors up mind!!!)