Difference z-home and z-up

Hi guys and girls,

Recently i did some changes to me z axis and recalibrated afterwards. Im unsing sprinter + pronterface. When I give the command to move the z axis up everything works fine and smooth but when I give the z home command the motor starts stalling and eventually blocks completely. Even when I disconnect the coupler and have the motor running freely I hear it skipping steps.
Also when the z up command hits the entstop the it just stops and doesnt the little "hit endstop, down a bit, up a bit routine"

If this behavior would show on all movements I would conclude a bad stepper driver ( I got the same behavior with a different motor) but it working normally when giving one command but not with the other seems weird.

So my question is first of all "why" and 2nd is there a firmware difference between z home and z up?

Edited 2 time(s). Last edit at 03/10/2014 10:21PM by sungod3k.

So what changes did you make to the Z axis? Was it working ok before?

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Waitaki 3D Printer

I got a finethread m8 instead of a 5/16" and switched to different printed motor brackets

Quote
sungod3k
Hi guys and girls,

Recently i did some changes to me z axis and recalibrated afterwards. Im unsing sprinter + pronterface. When I give the command to move the z axis up everything works fine and smooth but when I give the z home command the motor starts stalling and eventually blocks completely. Even when I disconnect the coupler and have the motor running freely I hear it skipping steps.
Also when the z up command hits the entstop the it just stops and doesnt the little "hit endstop, down a bit, up a bit routine"

If this behavior would show on all movements I would conclude a bad stepper driver ( I got the same behavior with a different motor) but it working normally when giving one command but not with the other seems weird.

So my question is first of all "why" and 2nd is there a firmware difference between z home and z up?

Z up will not test the endstop, it should stop on the endstop but not check the position. Z home does a re-test if set to do so because many run the initial homing speed very high so there may be an error when the switch is hit so it backs off and approaches at a slower speed to reduce error.

That makes sense, Im gonna test different drivers on different motors today to exclude bad drivers.

There is definitely less power when I home z i can easily stop the motor with one hand.

I just switched the steppers drivers, the axis and the motors and it doesnt matter what driver or motor I use the weird behavior show only when I home z. Which would indicate a firmware issue.

Quote
sungod3k
There is definitely less power when I home z i can easily stop the motor with one hand.

I just switched the steppers drivers, the axis and the motors and it doesnt matter what driver or motor I use the weird behavior show only when I home z. Which would indicate a firmware issue.

The firmware does not control power of the motor unless you have a board that has digital pots.

Skipping steps points to accel or speed being too high. I can only run my i3 at 3mm/s max and not sure of the acceleration right now.

tjb1 looks like you´re the winner

I just reuploaded the firmware and halved the homing speed. Looks like the additional z steps I had to add in order to compensate for the lesser pitch of my finethread z axis caused the speed to go up. Seems to work for now.

Edited 1 time(s). Last edit at 03/11/2014 05:12PM by sungod3k.