Z-axis unreliable zeroing

[TheDreamMaster]

I have not been able to print a SINGLE object properly with my i3 PRO C.

After solving countless issues and spending so many hours now I find that the Z-axis home zeroing is not repeatable.

I home all my axes, then calibrate the bed to extruder 0, and it all looks good. But when I go to print, and the printer auto homes all the axes again, the extruder comes down lower or higher than what I calibrated, resulting in the extruder either pressing hard against the glass or being away from the glass so far that the plastic does not even stick to it.

Each time I zero/home the z-axis its at a different position!!!

How do I solve this?

(This printer is a real nightmare)

[zhangxueyou]

How about re-uploading the firmware?
The firmware has been sent to your email.

[TheDreamMaster]

Thank you. I don''t think it is a software problem though.

Here is what I have found so far:

1. The Z-axis switch works perfectly. I have tested it repeatedly.
2. I measured the reliability of the zeroing using a caliper, measuring from the base of the left stepper motor to the bottom of the brass bushing on the threaded rod. I get a repeatability of +-0.03mm. That looks ok.
3. I measured the distance between the extruder nozzle and the heat bed and the repeatability when zeroing is almost 1.0mm!!! The problem is that it is just random, some times the extruder will come down and be just like I leveled it. And some times it just stops too high, or goes down below the bedsurface (when the extruder is off to the side of the bed).

This is what is causing the problem, something is not right and every time the z-axis zeroes to home, there is a chance that the heat bed will be too close or too far way from the extruder head.

The heat bed seems to be stable enough, so I am suspecting the print head to be the problem, or the x-axis. But I don't know why it would change so much each time. I have tightened the screws that hold the print head to the x-axis carriage and they are tight enough. No difference.

Any ideas?

[zhangxueyou]

Please check if z endstop is firmed.

[TheDreamMaster]

Yes, it is firmly attached.

As I mentioned in my previous post, the z-axis is moving reliably, but the extruder head seems to get misadjusted with respect to the heat bead.

AND NOW ANOTHER PROBLEM I JUST WANT TO CRY AT THIS POINT...

My extruder head is clogged. As I was troubleshooting the problem with the z-axis, doing test by printing a couple of layers, the extruder head is CLOGGED!!!

I can't believe it. I just want to print. I have been solving problems one after another for 3 weeks straight and have not been able to make this thing work

Am I just the unluckiest customer you ever had or is this a common situation?

[zhangxueyou]

How do you calibrate the distance between hot bed and nozzle?

[TheDreamMaster]

I raise the Z-axis a few mm. Then I zero (home) all axis. Then I turn off the stepper motors, manually move the hot bed and the print head so that the extruder is at one corner. Then I adjust the wing nut under the bed so that a piece of paper between the hot bed and the extruder has slight resistance to movement.

I repeat for the other corners, and check back on each to make a final adjustment so that the separation between bed and extruder feels the same (same resistance with piece of paper).

I have also done it using a digital caliper to check the space between the hot bed and the acrylic bed support is the same for each pair of corners, to ensure that the bed is planar.

Then I turn on the heat on the bed and the extruder and zero (home) the axes again. Many times, after zeroing, if I check, the spacing between the bed and the extruder is different than what I just leveled it at. Much higher or much lower, almost 1 mm.

[zhangxueyou]

So why don't you try to re-upload the firmware? Maybe the problem really exists in the firmware. To be frank, I've never met someone has such an issue like yours.

[TheDreamMaster]

I will try the firmware.

[TheDreamMaster]

I cant find any documentation on how to update the firmware.

The rar file I got via email jus has the c++, arduino, processing sketch and libraries but no instructions. It even has a Blink.cpp coding example, which I am sure is not part of the actual firmware Maybe included for testing purposes.