Re: Does control s/w affect machine performance? max step rate

Art put it very well.

The "quality" of the step pulses really matters for how much power
you will get from a motor. "Ragged" pulse timing robs motors of
torque that could be applied to a load. Instead it wastes it on
pointless accel/decel torque loads.

Perfect pulses are evenly spaced at any speed. This never happens in
the digital world though you can come very close.

Barring anything else, a pulse generator that can generate
extraordinary step pulse rates can also be depended on to produce
very evenly spaced ones at lower speeds.

But how about if you really need high pulse frequencies, what would
the conditions be? Let's say you have a 1,000 line encoder on a servo
motor that has a 6,000 RPM rated speed. 1,000 lines means 4,000
counts per revolution; 6,000 RPM is 100 revs/sec, so it would take
100 times 4,000 or 400,000 step pulses per second to get what you
need.

Or how about you have a Compumotor drive set a 125 microsteps per
step and you need 3,000 RPM. That's 50 revs/sec at 25,000 counts per
rev or 1.25MHz for a pulse rate. Suddenly a 4MHz pulse rate doesn't
seem too high. Comfortable but not too excessive as a matter of fact.

Just remember, nature abhors a vaccum; if something has the
capability, someone will find a way to fill it. Depend on that.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Art <fenerty@a...> wrote:
> Hi:
>
> >>> > >I'm not saying that super fast pulses don't have their
place, but
> is there a real need for them ?
>
> Currently Mach2 version 3.0 (unreleased) can drive a Gecko 2003
at 262411
> pulses per second. I, like many , thought that this was too much and
> wouldn't be used. What I have found in usage is that the 4Mhz base
of the 6
> channel asyncronous pulsers creates a pulse stream more stable than
any I
> have seen, the end result meant that the stepper motor tests
actually ran
> the steppers faster than possible before. While I don't even
approach the
> max of 262411Hz on my little machines, the motors in testing do run
at
> amazing speeds with great smoothness. Sometimes, it isn't the end
speed
> thats important, its the harmonic purity created by the high
frequency base.
> Master5 users from 8Khz noticed a huge increase in smoothness when
Mach1 and
> 2 went to 25000Hz and higher as their base even if they didn't
increase
> their end speed due to mechanical limitations.. Seeing the gecko
run at
> 262411Hz is another magnitude of this effect... I think when all is
said and
> done, its a lot like having a 1000watt stereo. It tends to sound
better at
> 50Watts than a 100Watt amplifier running at 50Watts. Kinda the same
effect,
> different reasons....
>
> Just my two cents...
> Art
> www.artofcnc.ca