HEAD SHOOT TO TOP OF Z AXIS AFTER PRINTS

I am not sure what happened but I flashed the firmware of my TAZ5 and it seems like I am having 2 issues.

  1. The printhead shoots to the very top of the Z axis after prints and I find this annoying. Is there some code I can tweak in Cura before saving my Gcode to maybe just lift the head 10mm off the print and stop? Where is this code found in Cura?

  2. The left stepper motor and right motor must not be isync because the left side ends much higher than the right. Any suggestions? Is there a hardware or motor issue or can this be in the code?

Thanks a lot!

Chris

The Z axis not level issue is usually going to either be hardware or allignment. To get them bacl where they should be, run the Z axis down to the bottom, then power off the machine and unplug the Z motors to prevent electromagnetic pulse back into the board. Now manually turn the right hand motor until the distance with calipers from the top of the lower Z axis bearing to the bottom of the Z axis leadscrew nut on that side is identical to the measurement from the other side. Then reconnect the motors and power the printer back on. Then re-level your bed. You will also want to check for a loose Z axis motor coupler. You should have at least one of the two setscrews per top or bottom of the coupler resting in the center of the flat spot on the motor shaft and the leadscrew shaft, with the other screw on each side down tight. If any setscrews are missing, replace them before operating the Z axis.

After that, lubricate the Z axis leadscrews (and just the leadscrews, not the smooth rods) with White Lithium Grease. Then run the carriage up and down a few times. If the issue occurs again you either have another allignment issue, a failing Z motor, or your measurement was off. Check that the leadscrews are up and tight to the top of the upper bearing, and the lower Z motor mounts are all the way up and the same height on both sides. Then check for frame square. You may want to also try loosening the idler side X axis rod retaining bolts and running the Z axis up and down a few times to make sure that isn’t pinched or bowed out.

Thanks Piercet. let me try these recommendations and get back to you.

Is their something I can do to eliminate the print head shooting as high up as possible after prints. It just started doing this after I installed the newest version of Cura and flashed my firmware. I know this is a gcode issue but I am not well versed in it.

Thanks,
Chris

In Cura, go to the Expert -> Switch to Full Settings menu. Say yes to the prompt to copy the values over.

Now there is a tab for Start/End-GCode, go to the “end.gcode” section. It should be pretty well commented if it’s a lulzbot profile.

So I am seeing z positioning of 250. Is his high?

Thanks.

Z 250 is 250 units up off from the bed, in this case the units are defined as milimeters, so yes, that is almost to the top of the Z axis. x0,y0,z0 is located at the lower leftmost corner of the bed.

Try replacing

G92 E0
G1 E-3 F300
G1 X5 Y5 Z250 F1000

with

G91                            ; relative positioning
G1 E-1 F300                    ; retract the filament a bit before lifting the nozzle, to release some of the pressure
G1 Z+20 E-5 X-20 Y-20 F3000    ; move Z up a bit and retract filament even more

It moves it up 20mm relatively from the CURRENT position, so 20mm above the model

Sweet! Thanks I will give it a try!

Thanks.

Chris

I really would not recommend a relative move, if your model/print went up to 240 Z or so it would crash into the top on the frame doing that.

I posted that from the lulzbot cura profile for taz 6, which does have a z endstop switch. I should have stated that.

Thans for your comments. So since there is no end stop at the top of the z axis should I adjust that value based on the height of each individual print?

Thanks,
Chris

Either that or put a note to yourself that if you print something over 230mm tall you need to adjust it. I’m guessing that wouldn’t be that often?

So is full travel on the Z axis 250? Is this the limit?

Thanks.

Chris

Yes. Print Area: 290mm x 275mm x 250mm (11.4in x 10.8in x 9.8in)
https://www.lulzbot.com/store/printers/lulzbot-taz-5

So where would 0,0,0 be on the bed? What position would this be? Front left corner all the way down?

Thanks,
Chris