Z axis calibration failure
After several hours of reading forums and the manual and trying to figure this out, I figured I might as well ask. After building my kit, I can't get Z to calibrate. The odd thing that's leading me from most answers is that when if I go into settings to manually move my Z, it seems to operate smoothly. When I try to cal on Z, it gets to a certain point and then does a sort of stutter or hop and then stops telling me it failed. It did, on one try, go all the way to the top, but on the way down when it hits that same area, it stuttered again and stopped. This seems to be the right motor and about.. 1/3rd of the way from the motor along the length of the shaft. In my other life, if this were one of my known tools I'd say there was a problem at that point with the grooves in the shaft.
One post by another user was solved by someone suggesting a light application of bearing grease. I can't see as it'd hurt anything, but again, if it was a bearing issue, I'd think it would be happening along the entire shaft.
I've also seen a post by Prusa saying that if the zip ties on that side is too tight it could damage the motor and lead to failure. Again, I'd be inclined to maybe check that but it's only in one spot.
Anyways... New user here. Hopeful to get this sorted and resolved so I can start on this list of things I want to make and print that I've been adding to since I hit that buy button.
RE: Z axis calibration failure
Check the rod diameter at the spot where it stops. You may have a faulty rod that's thicker at one point. Check the rod alignment. The rods may not be entirely parallel. Check that when you remove the Z motors (entirely) and put the printer on its back, so that the Z rods are horizontal, you can move the whole X assembly freely on the Z rods. Try to swap the Z bearings or rods between left and right and observe whether anything changes.
The tolerances on these parts aren't great and when you match a too thick rod and a too thin bearing, there may be quite some resistance when moving.
When the printer is calibrating the Z axis, the maximum current threshold for the motors is lowered a lot, so as not to hit the top of the printer too hard. That threshold is how the printer detects it hit the top of the printer. And I believe that's what triggers here. The motors have to work more, they exceed the threshold, the printer thinks it reached the top.
RE: Z axis calibration failure
A simple cause - and it happens even to folk like me - the dust cover can jam the motor shaft when the are too close. Unscrew the dust cover a full turn above the motor and see if it helps.
Second test is to swap the cables at the Einsy. If the stutter changes sides, it may be a driver issue. If the stutter stays on the same side, more likely a motor/screw/bearing effect.
You can remove the T-nut screws so the X-axis floats on the bearings. And try running the X carriage up and down feeling for rough spots. But keeping it from torquing is a problem, and you need to be careful to not bend anything. Flipping the printer may help; but watch for a free falling Y axis and possible cable damage. Don't bend any of the harnesses at sharp angles.
RE: Z axis calibration failure
Second test is to swap the cables at the Einsy. If the stutter changes sides, it may be a driver issue. If the stutter stays on the same side, more likely a motor/screw/bearing effect.
There aren't separate drivers for the left and right Z motors on the Einsy. The connectors are both connected to the same outputs of a single Trinamic driver.
RE: Z axis calibration failure
I'm having a similar problem after upgrading my MK3 to MK3S. Prior to the upgrade it worked like a champ. Now it won't calibrate the Z axis. There don't appear to be any mechanical problems, and I've verified that the PINDA works.
RE: Z axis calibration failure
The two motor connectors on the EINSY are parallel, to a point. I knew that -- lol -- but swapping the cables can test if one of the driver connectors is fritzing out and helps verify both were firmly seated to begin with. I should have worded it better.
RE: Z axis calibration failure
Thanks everyone. It was the dust cap. I moved it up a full turn and problem solved. I still have some other issues now as I can't get a good test print yet, but at least I made it past the calibration steps.