Dual Z axis.

MrNiceguy

I had this problem as well, i'm not really sure how I fixed it but I know it had something to do with the drive settings in your firmware.

SLKittie

i am running through all options again. re leveled. checked angles. looking through config.g
See thats what i was thinking to.
but cant figure out what.
are you still using the same config file?

JoergS5

@latexcupcake You can try to set one side a bit higher or lower by turning one of the Z axis by hand and test movement again. It may not be exactly calibrated. I would turn it a bit and count the turns, so you can turn back after the test.

Another possibility is that the horizontal axis puts a force against your two z axes, so you should change this distance. You can find out by testing by hand whether the two z-axes are very stiff or not in horizontal direction.

Another possibility is that the ball bushings of the z axis is moving stiff. This may be due to dust in the cage. You should disassable, clean and oil it then.

SLKittie

@joergs5 Appreciated i have tried this but all help is welcome.

Both axis when not powered move fine and free.

JoergS5

@latexcupcake If no tip helps, you can make a short video and show us, this may give a hint what's the reason.

MrNiceguy

This is my config:

; Drives
M569 P0 S1                                 	; Drive 0 goes forwards
M569 P1 S1                                 	; Drive 1 goes forwards
M569 P2 S0                                 	; Drive 2 goes backwards
M569 P3 S1                                 	; Drive 3 goes forwards
M350 X16 Y16 Z16 E16 I1                    	; Configure microstepping with interpolation
M92 X100 Y100 Z1600 E95                		; Set steps per mm 
M566 X1200 Y1200 Z4.5 E300                 	; Set maximum instantaneous speed changes (mm/min)
M203 X24000 Y24000 Z120 E3000              	; Set maximum speeds (mm/min)
M201 X1000 Y1000 Z100 E5000               	; Set accelerations (mm/s^2)
M204 P400 T400                            	; Lower accelerations when printing though
M906 X750 Y750 Z750 E750                   	; Set motor currents (mA)
M84 S0                                     	; Disable motor idle current reduction

I am having some struggles with under extrusion on my Anet A8 so I wouldn't copy the E values.
I also changed my leadscrews to some with a lower leadscrew pitch, so the steps per mm for the standard rods should be 400.

SLKittie

Ahaha. it was the z steps. it was set to 4000. (done through RRF) changed it to 1600 and works properly now. i knew it was something simple but just couldnt see it. ((yeah mine had a 2020 x axis now, im going to be making it into a hypercube at some point.) looking at bearing lead screws for the z axis maybe.)

Thank you both for all your help.

MrNiceguy

Glad I could help

wilriker

@latexcupcake said in Dual Z axis.:

Ahaha. it was the z steps. it was set to 4000. (done through RRF) changed it to 1600 and works properly now.

Just to confirm this: did you also change your lead screw? Because as @MrNiceguy pointed out the stock Anet A8 has 400 steps/mm. It still might run with 1600 steps/mm but the positions would be way off in this case.

JoergS5

@latexcupcake Nice that you have a solution now and can print now.

If you want to optimize in the future, you can consider using only one stepper and connecting the Z axes with a belt. Then a calibrated horizontal X axis will stay horizontal. Using two steppers, there can occur desynchronization after you turned off the printer.

Just for completeness of my comment: I read that the trapezoid spindles have tolerances, so a 8x2 is not exactly 2 mm. To have two identical spindles, I read one can buy one large one (600 mm)and cut it in half. Then you have two identical 300 mm ones.

SLKittie

@wilriker No didn't change the lead screw. but once i got stuff working. I did a re-calibration of all axis's.
Need a bit more fine tuning but 20 mm print was 20.23mm so cant complain lol.

@JoergS5 eventually I will be using one stepper, doing that. Yeah i didn't know about the spindles being off but that does make sense. I will take that into account and grab a long spindle to cut in half, well that's if i don't come across anything else to use for the z axis. (hyper-cube set up)