Horizontal lines

Ringo1508

So while I wait for my new motor, I hope I'm not going to beat a dead horse with this parallel vs series. I know (after reading a bunch of other posts) that in series both motors get full current but half the voltage whereas in parallel it's inverse. If I'm running 24V then both these 8V motors would be fine. My question now is, if ramps board (Prusa i3 MK2S) is running Z motors in parallel due to 12V PSU, and the Marlin firmware settings are compiled with 830ma, then each Z motor is only getting 415ma?

Assuming the above is correct, then to simplify life for me on 24V PSU, I can keep them in series and then just set Z current to 450ma like I had before and be good?

Is there a benefit from wiring one to ZA and one to E1? Which would you do if it were your printer? lol (easiest way to ask)

Veti

see
https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors

Phaedrux

If I had a free motor driver I would give each Z motor it's own driver and use the link Veti provided to do a self leveling routine, much the same way that prusa rams the X axis into the top of the printer to ensure they are even.

I'm not really savvy on how serial versus parallel wiring would affect your particular motors given your PSU voltages. DC42 would have a better idea I'm sure.

dc42

@ringo1508 said in Horizontal lines:

@dc42, let me know if you think I should run ZA and E1 for my motors (24V PSU.) Will I lose the mesh bed leveling with the P7:7 command that figures out my points automatically if I switch to this?

Yes, I suggest you do that. It won't affect mesh bed compensation.

Ringo1508

Thank you @dc42, @Veti, and @Phaedrux. Once I get my new motor in I'll try a print before swapping the Z motors to the new set up and then swap the motors and post back for anyone that stumbles on this thread who might have the same issue.

Ringo1508

Just an update.

I received my new motors (same motors, just new ones) as the other seemed to have a bent shaft. I did the following tests:

printed cube on my Prusa i3 MK2.5 Bear with TMC2208 X and Y external drivers
printed cube using one of my other 1.8deg stepper motors as X motor (Z motors connected to ZA and ZB)
printed cube using new 0.9deg replacement X motor (Z motors connected to ZA and ZB)
printed cube using new 0.9deg replacement X motor using "faster" slicer profile (Z motors connected to ZA and E1)
printed cube using new 0.9deg replacement X motor using "slower" slicer profile (Z motors connected to ZA and E1)

Cubes in picture are 1 through 5 from left to right.

Interestingly enough, I do see the lines/differences on the Prusa and might be worse than the Duet printer! (hah!)

I don't see a huge difference between any of these. If you zoom in, you can definitely see the line differences. Maybe I just didn't pay as much attention to them before getting into "building my own printer" phase? Do these lines look normal/acceptable to others? Should I work on trying to get them smoother or more uniform?

I'm using Amazon PETG and I did put them in the food dehydrator on 140F for 8+ hours before printing with them in order to make sure moisture wasn't a variable.

Other things I did:

confirmed that X, Y, and Z axes are dang near perfectly square
made sure belts were not too tight or too loose
found the X carriage to have a weird tension when moving, then got easier to move, then harder, then easier ...loosened grub screws and moved the 16T pulley a little bit away from motor housing and tightened grub screws up ...this fixed that (I guess it was rubbing, which makes me think there's still a little wobble to the shaft)

I guess I just live with it I'll try printing that speed and acceleration print again and see if it looks like the original pictures I posted.

Veti

@ringo1508 said in Horizontal lines:

Amazon PETG

thats the worst petg i have tried so far.
unfortunately i ordered 3 rolls. used up 1 to figure out how to print it well.
the other 2 are still unused. ordered different petg and was much happier.

Ringo1508

@veti, I'll try the Atomic PETG I have then ...or see if I have some Hatchbox left over.

My next test will also to be to use S3D to slice it and see if that makes a difference. At least now I'm happy to know it's most likely not a mechanical issue. I do like having motors on different drivers now too.

@veti, do you have experience using multiple drivers for Z? I followed the link. I just want to make sure what I'm doing is good, or too much, or if there's something better:

bed.g

M561 ; clear any bed transform
G28  ; home all axes
G30 P0 X11 Y105 Z-99999 ; probe near a leadscrew, half way along Y axis
G30 P1 X220 Y105 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors
G30 P0 X11 Y105 Z-99999 ; probe near a leadscrew, half way along Y axis
G30 P1 X220 Y105 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors
G30 P0 X11 Y105 Z-99999 ; probe near a leadscrew, half way along Y axis
G30 P1 X220 Y105 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors
G29  ; probe the bed and enable compensation

I have 2 motors (i3 style printer) so I'm making sure that the bed gets leveled between the two motors before doing teh G29. My config.g has the following in it:

config.g snippet

; Z-Probe
M574 Z1 S2					; Set endstops controlled by probe
M558 P5 H5 F600 T3000 A3			; Set Z probe type to switch and the dive height + speeds
G31 P500 X0 Y0 Z0.9				; Set Z probe trigger value, offset and trigger height
M557 X11:220 Y5:196 P7:7			; Define mesh grid

Veti

whats your M671 line?

Ringo1508

@veti

M569 P0 S0					; Physical drive 0 goes backwards X
M569 P1 S0					; Physical drive 1 goes backwards Y
M584 X0 Y1 Z2:4 E3				; Set drive mapping, two z motors connected to driver outputs z and E1
M569 P2 S0 V0					; Physical drive 2 goes backwards Z
M569 P4 S0 V0					; Physical drive 4 goes backwards Z
M569 P3 S1					; Physical drive 3 goes forwards E0
M671 X-39:291 Y0:0 S0.5				; leadscrews at left and right of x axis

I noticed when I accidentally manually moved the X axis on the Z lead screws that it wouldn't calibrate the X axis due to being more than 1mm offset, so I had to do the Prusa method of lowering the current on Z motors and ramming the top of the printer first. I guess I could up S0.5 to S2?

Veti

what firmware version? i think there was a problem in one of the rc releases.

Ringo1508

@veti

Firmware Name: RepRapFirmware for Duet 2 Maestro
Firmware Electronics: Duet Maestro 1.0
Firmware Version: 2.03RC2 (2019-05-14b2)
Web Interface Version: 1.22.6

Veti

update to the latest 2.03 rc and try again

Ringo1508

@veti do you think there's an issue with the version that's causing those horizontal lines? or is it something with the dual driver motor setup? (which seems to work great)

Veti

i thought you said something about the leveling.

did you try the disconnection of the coupler and moving the gantry? as is said any ever so slight resistance can cause this.

Ringo1508

@veti I have no couplers (lead screw is part of the motor)

The only issue I have with leveling is that if I accidentally move the X gantry manually, if it's more than 1mm offset, then I have to ram it into the top before trying the leveling. I'm just going to try changing the S parameter of M671 to a higher number and see if that works. I used the default S0.5 that was in the documentation.

When the machine is powered off, it is effortless to rotate the Z leads (they move smoothly)

It might be Amazon PETG

Veti

@ringo1508 said in Horizontal lines:

When the machine is powered off, it is effortless to rotate the Z leads (they move smoothly)

that is not going to tell you if there is slight binding. try unscrewing the lead screw nuts.

Ringo1508

@veti which part are you talking about? Here are my lead screws, Z motors, and the X ends.

Veti

the black thing on top. so you can move the gantry up and down without the lead screw.

Ringo1508

@veti got it! Yes, if I take those 4 screws out (two on either side) the gantry is completely loose of the printer and doesn't touch the lead screws at all. I'll make sure to not snug those screws too much.