Why can I not control my motors?

[Guyren Howe]

So Mark was good enough to come out and look at my setup. At that time, I could control 2 of my four motors. He suggested I had dead Pololus.

So I ordered 4 new ones. Put them in, cranked it up, and *great*, I can control all 4 motors.

For about 30 seconds. Then they stopped working, and I’ve got nothing.

The Arduino acts like it’s doing things, but it isn’t.

Can anyone suggest how I keep burning out pololus, or whatever else might be going on? I can’t keep dropping $50 on pololus like this.

[doog]

It sounds like maybe your wiring was verified but without any symptoms
of what was going on, noone can really help you here on a forum.
Things to consider: Were the steppers getting hot? Were the stepper
drivers getting hot? Do the software and firmware versions work
together? Have you tested a motor and controller individually?

From what I've seen, RepRap might look like a "build it and it'll be
fun" toy but like most open source projects, it requires lots of
skills in diverse areas and this one requires very diverse skills
since it's basically an electro-mechanical software controlled
robotics system. You need to know electronic circuits enough to read
and verify schematics, mechanical skills to assemble correctly( non-
binding parts ) and then there's the software side which is both
computer based and embedded(ie firmware based). So you see, trouble
shooting this in email is not likely unless you can pin down the
problem besides 'it doesn't work'.

Doug

[Guyren Howe]

On Sep 28, 2011, at 2:32 PM, doog wrote:

> Were the steppers getting hot? Were the stepper
> drivers getting hot?

Yes and yes.

> Do the software and firmware versions work
> together?

Enough to make the motors move for a minute. With previous pololus, enough to make two of the motors move at will.

Otherwise, how would I tell what the answer to this question is?

> Have you tested a motor and controller individually?

I can wire up a single motor and try to make it move with Repsnapper or whatever, and it doesn’t move (or get hot) any more.

Or do you mean something else?

[Jordan Miller]

you just had the potentiometers turned up too high. the pololus auto
shut off if too hot.
measure the resistance of your motor coils (the red and blue wires or
the black ad green wires).

the rule of thumb is turn the pololus all the way DOWN. then tell the
bot to move 10 mm at something slow like 500 mm/min. nothing should
move. then barely turn up the pololu potentiometer. then move the
motor again. keep repeating this. at some point the motor will just
barely be able to move. then turn the speed up to 1000 mm/min. try to
move the motor again. continue until you find the max speed you can
drive that axis. that will be a function of the motor you chose and
the friction you have on that axis. if it's not fast enough for you
your options are either to get a stronger motor or reduce the friction
on that axis.

do that for all of your motors and also your stepper on the extruder.

make sense?

jordan

[Guyren Howe]

On Sep 28, 2011, at 2:55 PM, Jordan Miller wrote:

> make sense?

Yes, thanks. I will try that.

[Jordan Miller]

I feel your pain though, I had the same exact problems when just
starting out... it seems trivial to the EE people but it's
incomprehensible to the rest of us. consider it a crash course in
electronics.

and if you get the motors running and then go for the hotend... be
careful, heat is hot! I have a couple battle scars to prove it.

:)

jordan