RE: [CAD_CAM_EDM_DRO] CNC Stepper Power Supply Q's???

> -----Original Message-----
> I think I get it, but lets start with the Basics.
>
> 1. More Voltage means More RPM.

With steppers and assuming you have some method of limiting the current,
Yes.

> 2. More Amperage means More Torque.

Sort of but not really. If we are talking holding torque or very slow
motion than yes as you increase the current up to the rated maximum your
torque will increase. But, once you get things moving much of any RPM
inductance takes over and voltage will control the amount of torque you
have (and because of that the maximum RPM). Effectively once in motion
the voltages ability to overcome inductance and get current flowing in
the coil is what determines the torque. Amperage setting will have
virtually no effect once you hit a particular point on the RPM curve as
there will not be enough on time for a coil to reach full current due to
the inductance. At that point it is all down hill as you go faster.
Torqu continues to drop with speed until it gets so low that it meets
the power requirement to go at that speed. This is why running a motor
at reduced amperage will not affect your maximum RPM.

> So now I know that my Series 1 was equipped with 8.2 Amp 56V
> steppers. I want to obviously come as close as I can to those numbers
> or possibly exceed them. Right???

No, you never want to exceed the amperage unless you have a desire to
buy new motors (which is one way to increase your performance). If you
run the Gecko's at 60 - 75 volts you will get great performance. Yes
there are some that have gone through great trouble to get an exactly 80
v supply and they do get marginally better rapids. Not worth the effort
in my book if you happen to have a 65 v supply on hand. I was running my
Series II with stock motor with a G210 at 60 v and getting 75 ipm rapids
reliably and had very little worry about deceleration pushing the
voltage over 80 and smoking the drives. In my book not running at 100%
of design is the way to get durability and reliability. Safety margin is
a good thing.

> So I am going to use Gecko's, this much I do know at this point.
> However I will loose some torque because the Gecko's can only sustain
> 7 AMPs. However will I gain some RPM because I can run 72V to the
> motors???

> Finally, I have never built a power supply before, does anyone have a
> good resource or page to help me along?

Please go to the Gecko site and read the stepper white papers. As
already pointed out today it covers power supply design and will also
get you on track about how a stepper motor works.

>
>
> Addresses:
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>
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