Z-Axis wont move up during print (Solved with new Firmware)

[martinez]

Hello,
recently built my GEEETech i3 Pro B.

After getting rid of wrong direction of x-Axis (changed parameter in Configuration.h) and a plugged nozzle (burned it free with small torch) I can now try my first prints. I also exchanged bent Z-axis threaded M8 rods that came with the kit for new, more straight, stainless steel rods.

Unfortunately i noticed, that during print the Z-axis wont move upwoards when a new layer begins and it should move upwoards.

With manual control or during the home-procedure it does work. No stuck motors are the issue!

What could be the issue? I am using Repetier Host, newest Version (not the old GEEETech version).
Some wrong parameters? Where should I look? What should I consider?

[William]

do one z axis motor or two z axis motors not work?

[martinez]

Hello,
yes, both motors do not turn to make z-axis move up during print.
Both motors turn when controlling z-axis manually.

Just to make sure everyone understands: This is not a friction or stuck motor issue. I made sure they run very smooth, which they do.

Since I am very new to Slic3r, Marlin and Repetier I suspect this is a configuration issue.

[martinez]

I found the issue but no solution. In the G-Code for the print, there are of course Z-axis movement commands

Code: Select all

07:44:56.718 : N386 G1 Z1.7 F7800*30

The feedrate is far too high for my Z-axis. My printer can only handle approximate feedrate of 100, but the g-code tries to move it with a feedrate of 7800 which is too high. When I manually send the command

Code: Select all

G1 Z5 F7800

the printer will not move. If i send

Code: Select all

G1 Z5 F100

instead, the printer will move.

But sometimes if I send the command with the high feedrate, the printer will move at the firmware limitation speed of 2 mm per second. I dont get it. I dont know why sometimes the firmware or whatever seems to be able to cope with high feedrate and just limit it to its maximum, and sometimes the printer will try to transcribe that high feedrate and of course not be able to really do it and don't move at all.

[martinez]

Well, I solved it somehow.

What did I do?
I applied the newest firmware for marlin from here https://github.com/MarlinFirmware/Marlin
Of course I needed to alter the configuration.h to make it work with my printer. I used the configuration.h from the original firmware for my printer from viewtopic.php?f=10&t=17046 as a template and took the values for some parameters from there for the new firmware.

Now the repetier host software does move the Z-axis as it should.

Now I could do my first (crude and not good) print.

[sjk]

I have been using my i3B for a couple of years and suddenly the problem you described appeared. Oddly, it sometimes works OK although there is a horrible screech from the motors.

I tracked it down to the very first couple of Z movement commands (speeds of 5000 up for 5mm and 7800 down to 0.3mm). If it gets through these then it's fine afterwards even though the speed for each layer is still 7800. Maybe the acceleration limit makes it Ok because the distance of 0.3mm is so small.

I'm frightened of trying to applying your fix as I would have no idea what I was doing. I wonder if anyone can definitively say that newer firmware addresses this issue?

[William]

Hi,
Please rest assured to update the firmware, this will solve your problem.