Hello guys!

Another noob here trying to build a P3Steel (Arduino + RAMPS1.4 (parallel Z output)+ TMC2100 + Nema17).

My problem is that I cannot use the function "going home" in Pronterface for the Z axis. When this function is activated, the motors don't move and vibrate. But I can move the Z axis manually setting the speed up to 150mm/min. (Marlin: 4000steps/mm for Z axis). I guess, Pronterface uses higher mm/min in going-home function but I couldn’t find how to configure this speed, neither in Marlin.

According to other posts, the problem should be a low torque -> low current regulation in the driver. So I have tried to rise up the current with the potentiometer to see if it solves the problem. Unfortunately I have reached values of 2V in Vref (2A Imax/ 1.41A Irms) with low improvements: The motors start moving and then loses all the steps. Also it has the negative effect to overheat the driver very fast (with heatsink installed). In manual movement the motor stops and continuous to move (overheat protection I suppose).

I have tried to move the X axis with the Z driver with no issues.
I have tried to move the Z axis with the X driver with the same poor results.
No jumpers are installed in any driver. (just for clarification)
For axis X and Y I used Vref = 0,8V (less than half I tried in Z) with no issues at all, even at high speeds.
Here a video that I have done yesterday so you can see how it moves in manual:

My question is: Could be the speed for Going-home (Marlin/Pronterface) changed? Is the Z speed in the video acceptable for printing?
I would prefer to avoid solution like put both motor in line instead parallel, but I can understand that these motor could need higher current as other in the market.

Any idea??

Edited 1 time(s). Last edit at 07/07/2016 05:43PM by Arteriel.

Hello all,

I could find where the speed is defined inside Marlin. I was lucky and a 3 year old post has given me the answer. I was looking for the wrong name...

If someone want to know, I have just adapted the values for Z axis to slow down the maximum and the homing speed:

In configuration.h:
#define HOMING_FEEDRATE {50*60, 50*60, 3*60, 0} // set the homing speeds (mm/min)
// default settings
#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,500} // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE {300, 300, 3, 25} // (mm/sec)

Regards!

I'm glad you solved it. In future, you may wish to ask questions relating to Marlin firmware here [forums.reprap.org].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].