Some help with my RAMPS 1.4 and stepper motors

[Jeffrey]

I'm hitting a wall, and either I'm making a mistake, or I have some faulty stepper motors

I have five stepsticks and several Minebea17PM-K502-P1ST stepper motors (http://cncsuperstore.com/index.php?route=product/product&product_id=64) which I have used successfully with an arduino board, making them rotate, etc.

I recently purchased a RAMPS 1.4 (listed as having been tested) and a Arduino Mega clone board.  Great!  the boards seem to talk to one another okay

I have a 400 Watt (antec brand) PSU 

I can't get my stepper to do anything more than whine or shiver at best with all of the microstep jumpers in. 

with the jumpers out, the stepper rotates, but doesn't seem to hold well, and looks as if it goes backwards some times.

I believe I have my stepper's A+/A-/B+/B- wiring correct (the stepper don't use the standard color coding,(Orange- B-, Blue-  B+, Red-   A+, Yellow-  A-)

I'm getting so close to having my printer setup and running, I could use some help.

Jeffrey

[doug metzler]

Did you dial up the current?  There's a tiny trim-potentiometer on the board.  Try setting your motors a-spinning, then dial up the current until they start to move.  Keep an eye on the temperature of the drivers, if they get too hot they'll go into thermal shutdown and your steppers will become erratic.  In that case dial it back a bit.

If that doesn't fix it then post back here.

Thanks,

DougM

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[Jeffrey]

Thank you for your reply!

Yes, I have turned up the current by using the trim-pot on each of the stepsticks

If I have the jumpers pulled to disable microstepping, I get some, somewhat erratic, rotation.

I did get some heatsinks for the stepper drivers so I will mount those.

Any other suggestions?

Jeffrey

[Ronald Aldrich]

Jeffrey,

It sounds to me as though you either have a bad connection, or that the motors wires are not paired properly.

The wires should be connected to RAMPS as AABB, where A is a pair, and B is a pair.  You can identify the pairs either by using a meter, or by disconnecting the motor, shorting two wires, and spinning the shaft.  If the motor's resistance to rotation goes up when a particular pair of wires are connected, then those wires are a pair.

- Ron

[Jeffrey]

Here's a bit of video I shot
http://youtu.be/5ZvuNL2lMVA

[doug metzler]

I'm kinda leaning towards the stepper drivers overheating and going into thermal shutdown.  My drivers have little heat sinks on them (see attached piccie) which yours don't appear to have.  It would be really nice if the drivers had an overheat indicator on them.

I'm comfortable that you've tested all wiring combinations of the motors and clearly the signals are getting sent, and you did mention in your video how hot the drivers are.

turn the current down as far as it will go.  See if the drivers cool off a bit.  If they do, then send it a step command and slowly turn the current up.  The steppers should buzz with lowest current, then start to turn as you turn up the current, then get erratic as you continue to turn up the current.  The driver in the piccie has the potentiometer up maybe 1/4 turn from the bottom, so not very high.

Let me know if this isn't the case.  If you can't find a sweet spot you might have to add heat sinks to your drivers.

Stepper motors almost never fail, but it does look like all your motors are the same - have you checked the resistance of all the coils in the motors and are they the same?

DougM

On Wed, Oct 2, 2013 at 11:35 PM, Jeffrey <jeffrey...@gmail.com> wrote:

Here's a bit of video I shot
http://youtu.be/5ZvuNL2lMVA