Re: [CAD_CAM_EDM_DRO] Digest Number 2090

On 20 Feb 02 at 19:55, CAD_CAM_EDM_DRO@yahoogroups.c is alleged to have
scribbled:

> Message: 22
> Date: Wed, 20 Feb 2002 14:28:59 -0500
> From: "Rick Miller" <apollo@...>
> Subject: Troubleshooting, part II
>
> I still couldn't get TurboCNC to make anything respond. Ditto with
> CNCPro. But, I ran "Stepster" and was able to get it to move, though not
> very well. Here's what happened:
>
> The motors aren't yet hooked up to anything, they're just sitting on a
> bench. I ran stepster, set the parameters & pins appropriately and tried
> moving the X & Y axes. The Y axis would move erratically, going between
> 60-120 degrees (approximately) in one direction, and somewhat less in
> the reverse direction. It almost seems like it's being sent too many
> steps too fast for the motor to react appropriately. The X axis
> wouldn't rotate at all; I think it took one step in one direction, then
> one step in the oppo I thought maybe something was wrong with the motor,
> so I switched the motor I had on the X-axis drive to the Y-axis drive,
> and vice-versa. I had the same results; what used to be the Y motor was
> now making that high pitched sound and not moving, and the what used to
> be the X motor was now moving in the same varying degrees of rotation
> that the (formerly) Y motor was.

I havn't used Stepster, but in TurboCNC 3.0g there are two things to look
at:
firstly set your max step rate to about 500. you can always make it
higher later. and set the acceleration to a slowish rate too, just in
case, thoug hbare motors can accelerate much quicker than when they are
loaded.

then, check your step pins ACTIVE state. most TTL logic run inverted, ie
'off' is logic high and active is low, so you want those pins to be pulsed
LOW to make the motor step. I had similar weirdness on a test rig where
I had the step pins set to 'active high' (ie they live low and pulse high
to step, it did what you describe)

once you have them running at a low step rate (it will jog at the max step
rate) you can find the correct max step rate using a binary search.
assuming the motors are connected to their working load of course, if
they're just running free they'll be able to run a lot faster but will
stall when mounted to the the machine.

the process....

say you've got them running at 500, double it and try.
if they're still doing fine, double again, if they now miss steps, set to
the average of the previous amount and the current amount. ie half way
between the 2 settings. repeat, ie if it now runs ok, go to halfway to
the figure where it did not run.
typically....

500 ok
1000 ok
2000 misses
1500 ok
1750 misses
1625 ok [= (1500+1750)/2 ]

you could go on till you found the cutting edge of stability, but setting
it a bit on the low side will prevent problems when you put a heavy object
on the table.


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