Re: Microstepping - a genuine PRIMER

Hi,

There is no decrease in torque at all compared to a half-step drive,
there is some compared to a full-step drive. None of that matters
though.

Everyone fixates on holding torque. The numbers seem impressive but
they are at best a guide what the motor will really do.

If you have a bolt that was rusted in its threads, it will have a
very impressive "holding torque", but you would know the difference
between it and a motor.

What makes a motor diffrent from a rusty bolt is a motor develops
torque while turning. This introduces the concept of power; power
equals speed TIMES torque. Power is what gets thing done.

A rusty bolt may have 10,000 oz-in of torque but it has ZERO power
because it is not turning.

Power can be expressed in horsepower or in Watts, it makes no
difference. 1 HP is the ability provide 550 lb of thrust or lift
while moving at 720 inches per second. This is also equal to 746
Watts.

A step motor's power output depends entirely on power supply voltage
and motor inductance if the drive is clean. By that I mean the drive
does not permit the motor to resonate. Resonance uses up torque
vibrating the motor that instead could have been applied to the load.

A gear ratio does not change power at all. It only changes the ratio
of torque to speed.

Since this seems to be an on and off again topic, I will run some
dynomometer tests (as time allows) for size 23 and 34 motors and
generate maximum shaft HP data versus power supply voltage for some
of the more common motors out there. This will give a reference for
what you can expect from these motors. Please let me know if anyone
is interested. Right now I'm up to my ears in running off a bunch
(2,000) of much improved G201s, (auto standby current, modular
connector, common GND interface, 10A per phase option, etc).

Mariss
Geckodrive Inc.

--- In CAD_CAM_EDM_DRO@egroups.com, thomasm923@a... wrote:
> Alan-
>
> One thing that I hear from time to time is that the holding torque
of
> some of these in-between steps is quite a bit less than in other
> steps, resulting in the increased likelyhood of missed steps. From
> what you've just explained, it seems to me that there isn't that
much
> of a decrease... Am I correct in assuming that?
>
> Tom Murray