RE: DeskNC Windows version

I just about got lost in the numbers on this discussion of stepping speed
and am thinking aloud in case others wondered through the same mental
jungle. Since I work from the digest, this discussion will likely be
settled by the time I post this...

Tim says--

>This works out to 10,000 steps per inch times 180 ipm = 1,800,000 steps per
>minute divided by 60 = 30,000 steps per second.

Art responds--

>But I think that 10 motor turns per inch at 200 pulses per turn is 2000
>pulses per inch. This would make it 180 * 2000 / 60 = 6000 pulses per
>second in the example given. Encoders do not up the steps per second.

--

It seems that Art is thinking of a standard 200 ppr stepper motor, but Tim
is using a servo motors driving an encoder which provides the pulse to count
rather than to drive the motor to the next step.

My next question since 30khz seems quite high for the EMC driving a
parallel port. (Parallel ports in general will spit out pulses much faster
than that or I wouldn't get 10 pages per minute at 600 dpi resolution from
my printer.) I wondered if Tim was using the pulse multiplying version of
the servo driver. He says,

>But with the Gecko G320 it works fine and the accumulator does not care if
>the pulse is perfectly paced.

So I grabbed my printout of Mariss's papers and the 320 uses direct
step signal. One pulse in causes one change in the A/B phase relationship
of the encoder. I also seem to remember from long ago that Tim had these
encoders connected directly to the motor shaft rather than to the ball
screw so I'm forced to conclude that Tim is indeed running 30 kHz if he
gets 180 ipm travel. Not bad at all.

I have some little 200 ppr stepper motors here that Joel Jacobs got to 4000
RPM. Running CncPro and comparing with EMC, he says,

>Anyway, I was able to get it up to 200 ipm at 8000 spi! Let's see, thats
>about 1,600,000 steps/min or ~26,000/sec! Sounds like a little dentist
>drill! (email from Joel Jacobs 8 April, 2001)

You can see the box that he did that with at NAMES. So bring your
frequency meter or o-scope and get the proof.

Ray