Page 1 of 2

Pololu Pot Tweaking?

Posted: Thu Jul 05, 2012 3:16 am
by atanguay
I'm using the Buildlog Stepper Sheild and three Pololus (Poluli :? ) for my build, and I've seen mention of the ability to tweak the pots on the controllers (Pololu).

But I had yet to find anything talking about HOW they should be set, or why you'd need to change them.

My motors are turning and things seem to be going fine. I'm using the prescribed NEMA17s from Sparkfun, so it's a pretty vanilla setup.
Any ideas or advice is greatly appreciated.

Re: Pololu Pot Tweaking?

Posted: Thu Jul 05, 2012 4:44 am
by dointhangs
atanguay the electronics page on the wiki section has the section on this - you have to put the + voltmeter lead on the little spot and then then ground the other someplace. Theres a picture there. I was getting sporadic movement from my nema17's before I adjusted the voltage (current is too high for their rating). Edward was telling me at makers faire that they ship these things at a high current setting. Thats great you arent having problems as is but if anything funny starts happening you will probably want to do that.

Re: Pololu Pot Tweaking?

Posted: Thu Jul 05, 2012 12:25 pm
by Burke LaShell
the electronics page on the wiki section has the section on this
Here's the link...
http://www.shapeoko.com/wiki/index.php/ ... er_Drivers

Re: Pololu Pot Tweaking?

Posted: Thu Jul 05, 2012 5:57 pm
by atanguay
Aha! Thanks you guys. I had missed this.
Perfect

Re: Pololu Pot Tweaking?

Posted: Thu Jul 05, 2012 7:18 pm
by PLHS54
This may seem like a dumb question, but when you are adjusting the drivers, should EVERYTHING be plugged in; all motors, power from power supply, and power from the computer to the arduino?

Re: Pololu Pot Tweaking?

Posted: Thu Jul 05, 2012 8:41 pm
by Burke LaShell
should EVERYTHING be plugged in
All you need is power to the driver shield.

Re: Pololu Pot Tweaking?

Posted: Fri Jul 06, 2012 12:21 am
by atanguay
Any ideas how hot the heat sinks should be allowed to get?

When I plug in my PS, they start to get pretty darned hot pretty quickly.
I'm a little worried about them.

Re: Pololu Pot Tweaking?

Posted: Fri Jul 06, 2012 1:45 am
by Burke LaShell
I found three things:
*The heat sinks can get too hot to touch
*When they get too hot it shuts down/misses steps
*A small fan blowing across the heat sinks solves that problem

Re: Pololu Pot Tweaking?

Posted: Fri Jul 06, 2012 3:00 am
by CptanPanic
With max cooling, and what is max you can turn pot up to? All the way?

Re: Pololu Pot Tweaking?

Posted: Fri Jul 06, 2012 3:07 am
by levlandau2
The pots control the current going to the motor. The buildlog stepper shield guide says that V=I*0.4 , so if you measure 0.6V, that means the current going to the motors is 1.5A.

I currently have my pots set to the baseline 0.6V. I am not sure what the advantage is of running higher currents... would that damage the motors? would it make the motors run better?