Re: [CAD_CAM_EDM_DRO] Stepper Motor and Cable Shielding. Any tips?

I just started working with steppers a few weeks ago. To experiment, I
hooked 4 transistors up to the parallel port, and started programming. I now
have a small program that allows me to set number of steps, acceleration
curve and steps/sec, and my experience with this is, that a well-powered
stepper will do 400 steps/sec with no acceleration and 1500 steps/sec with
prober accleleration.
Even with the acceleration I still lost steps now and then, and it turned
out my power supply was not delivering a good, even power, and as a result
the stepper would sometimes loose a step, if the interference between the
step and the 'low' curreent of the powersupply meet up.

I don't know what that's called in english, but I added a 6600uf capasitor
on the powersupply, and I now never miss a step.

If you have a scope at hand, check the smoothness of your powersupply. If
not, connect a small speaker (with a resistor or something). If you get
noise, add some capasitors :)

--Michael

----- Original Message -----
From: "kaynrc" <tom.kay@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, July 22, 2002 4:53 PM
Subject: [CAD_CAM_EDM_DRO] Stepper Motor and Cable Shielding. Any tips?


> In case you follow more groups than just this, I have also posted
> this in the Master5 group, with few replies thus far.
>
> I have a semi-sick stepper system, with Dan Mauch's 5 amp boards and
> Master5 as the software so far. (I'd like to stay with that one). The
> motors are new, 521 oz-inch also from Camtronics.
>
> I lost lots of steps on a bench test, whether I add resistance to the
> motor shafts or not (by hand). So I am losing steps somewhere, no
> matter how I adjust the feedrates or pulses per inch etc.
>
> I'm starting to suspect RFI or EMI is important and hurting my
> system, even if there are other causes on top of that.
>
> Can someone point out any shielding tips with respect to:
>
> 1. The parallel port cable (I have already bought some shielded-
> twisted paired wires, so I'll be making a cable, but what about
> grounding? Ground at one end only, and to the computer casing????)
>
> 2. The motors. Do they give off a hailstorm of RFI from the wires?
>
> 3. The wires from the breakout board to driver boards. Shield these??
>
> 4. Ground my case which holds the 3 drivers? Grounded also to the PC
> casing??
>
> 5. Anything I may have missed or gotten totally wrong, feel free to
> add in. I have, by the way, done a search on shielding in this and
> other groups, and gotten a good beginning picture. But I don't feel
> that I have the full picture yet. OK, I'm slow !
>
> Thanks for any feedback. Tom.
>
>
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