Carve King Z axis struggling

[Goliathan]

I'm working on my CK enclosure and dedicated bench and wanted to address the Z axis issue that nearly ruined the project I was working on.

For quick backstory, I had a project mostly done and on my final operation the Z axis suddenly spazzed out and crashed into my work, starting to dig it out.  I was able to stop in time and more or less repair the damage, but the problem persisted.  There's something up with my Z axis.

It's not crashing against the stops, and the screw and coupler are arrow straight as new as I can tell.  Sometimes, when the z axis is near the top of its travel, it binds or something, causing it to lose its brains.  The video below shows what I'm seeing:

www.youtube.com/watch?v=b23wynoGY_w

As near as I can tell this is only happening near the top of the Z axis travel, but it happens while traveling up or down (the example video shows a downward failure).

Any ideas?  I hope it's something boneheaded that's easy to fix.

[stever]

Did you check the tightness of the set screws on the coupler?

[Goliathan]

As near as I can tell it's not slipping in the coupler. I did disconnect the coupler to check things and the motor seems to freewheel fine. Back together it's doing the same thing.

[stever]

Dec 30, 2018 14:05:01 GMT Goliathan said:

As near as I can tell it's not slipping in the coupler. I did disconnect the coupler to check things and the motor seems to freewheel fine. Back together it's doing the same thing.

With no power on, can you turn the coupler with a few fingers to where the z moves up and down freely from top to bottom, and back up?

[Bruce]

Also check with power on and the stepper engaged, you should not be able to turn the screw with your fingers. Check at the bottom of the Z axis carriage. The screw should be stiff and very hard to turn with your fingers.

[Derek the Admin]

Let’s see your settings by typing $$ in the command line.

Also, it could be that voltage is too low on the stepper driver or that the stepper driver itself is bad.

I’m guessing it’s a matter of stepper driver voltage setting or software setting though.

Also, does it stall on the upward travel?

[Goliathan]

I re-checked my driver voltages and if they were off at all they were slightly high. 0.671 was the worst. I re-tuned all four to be safe.

My settings dump is here:

Grbl 1.1f ['$' for help]
>>> $$
$0 = 10 (Step pulse time, microseconds)
$1 = 255 (Step idle delay, milliseconds)
$2 = 0 (Step pulse invert, mask)
$3 = 0 (Step direction invert, mask)
$4 = 0 (Invert step enable pin, boolean)
$5 = 0 (Invert limit pins, boolean)
$6 = 0 (Invert probe pin, boolean)
$10 = 1 (Status report options, mask)
$11 = 0.010 (Junction deviation, millimeters)
$12 = 0.002 (Arc tolerance, millimeters)
$13 = 0 (Report in inches, boolean)
$20 = 0 (Soft limits enable, boolean)
$21 = 0 (Hard limits enable, boolean)
$22 = 1 (Homing cycle enable, boolean)
$23 = 0 (Homing direction invert, mask)
$24 = 35.000 (Homing locate feed rate, mm/min)
$25 = 1200.000 (Homing search seek rate, mm/min)
$26 = 94 (Homing switch debounce delay, milliseconds)
$27 = 4.000 (Homing switch pull-off distance, millimeters)
$30 = 12000 (Maximum spindle speed, RPM)
$31 = 0 (Minimum spindle speed, RPM)
$32 = 0 (Laser-mode enable, boolean)
$100 = 200.000 (X-axis travel resolution, step/mm)
$101 = 200.000 (Y-axis travel resolution, step/mm)
$102 = 200.000 (Z-axis travel resolution, step/mm)
$110 = 3500.000 (X-axis maximum rate, mm/min)
$111 = 4400.000 (Y-axis maximum rate, mm/min)
$112 = 3000.000 (Z-axis maximum rate, mm/min)
$120 = 240.000 (X-axis acceleration, mm/sec^2)
$121 = 240.000 (Y-axis acceleration, mm/sec^2)
$122 = 240.000 (Z-axis acceleration, mm/sec^2)
$130 = 432.000 (X-axis maximum travel, millimeters)
$131 = 432.000 (Y-axis maximum travel, millimeters)
$132 = 95.000 (Z-axis maximum travel, millimeters)

[Goliathan]

... and yes, sometimes it does stall going upward.

[Derek the Admin]

Can you toss the spare stepper driver in there to see if you get the same result?

[Goliathan]

Swapped out the controller, adjusted, and it's still happening.

[Derek the Admin]

Gotcha. We'll swap the motor with you. It's rare for a motor to be bad but it does happen. Please email a link to this thread to [e-mail] so we can reference your order info and get one out.

Derek

[Goliathan]

Done and done. Thanks for jumping on this!