RE: [CAD_CAM_EDM_DRO] stepper issues

Thanks for the quick reply - It looks like we are driving this motor at
about 37 steps/sec - so that's like 26 milliseconds between pulse edges.
Haven't measured width - maybe I should? Seemed to stall easier at 37
steps/sec than at 33 steps/second, but still stalled at both speeds - AND at
slower speeds.

Motors are .7.5 deg, 100 ohm 22July91, 42SPM-24DCZD, not "DCZA" which I'm
having trouble finding a datasheet for. The "A" version is 5-6 V, son't
know about "D" version, but I'm trying to drive at 9V - are we asking for
trouble?

It actually looks like I should speed this motor up, rather than slow down.

Chuck Merja
<http://www.srvscience.org> www.srvscience.org
www.3rivers.net/~chuckm/index.htm

Lemelson-MIT Inventeams - http://web.mit.edu/invent/n-main.html

US FIRST Robotics - http://www.usfirst.org/
lat/long 47.52383 -111.67912
211 Adams Rd
Sun River, MT 59483
vx 406.264.5955
cell 406.799.5955
fax 406.264.5830

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of hannu
Sent: Saturday, November 17, 2007 7:27 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] stepper issues

How fast does it run in hz ? The step rate I mean.
You may be into mid-band resonance. Probable even - old round steppers,
yes ?
How many rpm does the motor turn at 9.6 V ?

If you slow down your step rate, resonance will go away.

I think I remember that for your use, its more important to get accurate
than to get fast.

ebiz_59 wrote:

>
> Thanks for all you help so far. I'm working with a high school
> freshman to get a stepper motor to run a certain number of steps and
> then stop - calibrate a small erector set car to run between 5 and 10
> meters (we'll be told specific distance at the competition) and then stop.
>
> We have combined 2 basic circuits to accomplish this task - a 555 as
> monostable (adjustable time) dumping into a 555 astable to give steps
> while monostable is saying "go" and the astable dumps into the trigger
> of a 5804.
>
> We get this circuit to drive a stacked can motor - we need like 30 to
> 45 seconds of run time. We don't have it hooked to the device yet -
> the motor is just driving another free running gear. The motor starts
> alright, but sometimes well into the run, it gets confused and
> stalls/reverses.
>
> A few notes about stuff we might have done wrong -
> 1 - we didn't use pullup/down resistors for the full, half, direction
> pins - we just tied them to +5 or gnd.
> 2 - we hard wired this on an soldered experiment board and have wires
> going everywhere. We initially did 3 circuits on 3 separate
> breadboards and had the same problem. I thought it might be the
> breadboards and the fact that we could only put about 7 V to the motor
> circuit, but we get the same results with a wired cicuit all on 1
> soldered breadboard and 9.6 V battery running the motors and dropped
> down through a 7805 to run the 555's and 5804.
> 3 - we are limited to 9.6 V max by the rules
> 4 - we didn't use a PIC for a couple reasons - I wanted him to learn
> about 555's, we didn't have PIC programmer in stock so I thought I'd
> have him work on the 555 path while I researched and acquired
> programmer - still hope to do this, but the competition that sparked
> this project is Tues, Nov 20, so we are trying desparately to get this
> circuit to work.
>
> We'd sure appreciate your help in where to look.
>
> Thanks again for your help so far, and for any you can give over the
> next few hours/days.
>
> Chuck
>
>

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