FW: [dorkbotsebastopol-blabber] Stepper annoyances

[bsilva]

Very interested.

In absense of any other announced DB event this wednesday, shall we get
together then?  Otherwise I have Thursday open.



Brad

On Mon, 7 Apr 2008, Steve Chalem wrote:

> Brad, I repeated the experiment with the changes we discussed, and got
> the same result.
>
> I separated the power supply from the electronics and also connnected
> the negative side to ground.  I put a bigger heat sink on the chip, and
> I also tested the setup with the easydriver initially cold.
>
> Again, the big motor went back and forth hesitantly and jerkily; and the
> small motor just fluttered.  Adjusting the pot did change the behavior,
> but there was no setting where either motor worked correctly.
>
> If you're  stillinterested in trying our setups side-by-side, let me
> know!
>
> --Steve
>
>
> ________________________________
>
> From: dorkbotsebastopol-blabber-bounces at music.columbia.edu
> [mailto:dorkbotsebastopol-blabber-bounces at music.columbia.edu] On Behalf
> Of Steve Chalem
> Sent: Monday, March 24, 2008 10:17 AM
> To: bsilva at sonic.net
> Cc: dorkbotsebastopol-blabber at dorkbot.org
> Subject: [dorkbotsebastopol-blabber] Stepper annoyances
>
>
> Brad, I'll try both motors with a just-powered-up ezdriver and let you
> know what happens.
>
> I'm in Oakland for a few days, so I won't be able to try it until
> Thursday or so.  (I'm also not expecting to make the Wed. nite meeting
> this week.)
>
> Re next steps, I'd like to compare your setup with mine and it'd be
> great to have your help diagnosing this.  Friday or next weekend should
> be good, or one day the following week.
>
> Meanwhile I'll try the above and also a bigger heat sink and twiddling
> the pot.
>
> --Steve
>
>
>
> ________________________________
>
> From: bsilva [mailto:bsilva at sonic.net]
> Sent: Sun 3/23/2008 9:29 PM
> To: Steve Chalem
> Cc: dorkbotsebastopol-blabber at dorkbot.org
> Subject: Re: Stepper annoyances
>
>
>
>
> Well, I have a small epson (looks like two pancake coils sandwiched
> together (Hmmm..  Two food metaphors in one sentence, must be hungry))
> and
> it's working fine.  One difference, it's a six wire unit and yours is a
> four.
>
> I think the next step is to bring my test setup to your shop along with
> my
> scope and see what's different.
>
> I'm not sure I can do this week though, I have some major paperwork to
> do
> along side my normal job.  I'll try though, I'm very curious about this.
>
>
> Brad
>
> P.S.  Does the stepper exhibt the same symptoms immediately after
> powering
> on the ezstepper?  i.e.  Could we looking at the ezstepper going into
> thermal shutdown?
>
> Two suggestions; try a bigger heatsink and try turning the current limit
> pot clockwise.  I've taken a real close look at the pot on my unit and
> viewed from the side you can see where a top and bottom piece of metal
> come together.  It appears that the wiper is directly opposite this
> fold.
> It also appears that if the wiper is pointed at the "adj" marking the
> current should be at its minimum.  That's assuming that your wiper is
> the
> same type as mine.  Hmm... too many vague statements in this paragraph.
> I think I'm going to write the guys at Sparkfun and ask them to put a
> pot
> on this thing where it's possible to have a clue as to how it's set.
>
>
>
> On Sun, 23 Mar 2008, Steve Chalem wrote:
>
> > Brad,
> >
> > I did some more tests, this time with an ezdriver connected *directly*
> to the arduino (no ribbon cable); the "wall-wart" 12v power supply;
> short, direct wiring between the ezdriver and the motor, and a solid
> ground connection between the motor/driver circuit and the arduino.
> >
> > Result: same as before!  The .4A vexta (or whatever) motor turns back
> and forth once the amp-limit trim pot is fine-tuned, but on closer
> examination is skipping a lot of steps.  The little epson motor just
> flutters.
> >
> > Our hypothesis that the problems are caused by 60hz noise reaching the
> "direction" pin still makes sense, although of course i can't confirm
> the presense of the noise without an oscilliscope.  BUT, I've done
> everything we discussed to eliminate noise and saw no change in
> behavior.
> >
> > One addl data point:  the only time I've actually witnessed an
> ezdriver operating a motor properly was when you had one connected to a
> bitwhacker.  I've never actually seen one work with an arduino.  I do
> know people are using this combination successfully.
> >
> > --Steve
> >
>
>
>