Puzzled by Z0 position and first layer print

dc42

Please upgrade to firmware 1.19.2. Also, to work around a known issue that is fixed in firmware 1.20, please add one M400 command right at the start of every tool change file that includes movement, and another at the end.

deckingman

@stephenc.
In another thread you mention that you have this in the start code of S3D.

G10 P0 R160 S200
G10 P1 R160 S200

From the wiki, it states:

"Remember that any parameter that you don't specify will automatically be set to the last value for that parameter. That usually means that you want explicitly to set Z0.0…................"

So, I'm just wondering if it's those G10 commands in your start gcode that are applying an offset.
HTH

dc42

@deckingman:

@stephenc.
In another thread you mention that you have this in the start code of S3D.

G10 P0 R160 S200
G10 P1 R160 S200

From the wiki, it states:

"Remember that any parameter that you don't specify will automatically be set to the last value for that parameter. That usually means that you want explicitly to set Z0.0…................"

So, I'm just wondering if it's those G10 commands in your start gcode that are applying an offset.
HTH

Those commands should leave the Z offset of each tool alone, so I don't think that's likely to be the problem. The tool offsets default to zero if they are never set.

stephenc

in my config I have G31 set as follow for z offset after probing which works perfectly when I have T0 printing only

; Endstops
M574 Z0 S0 ; Define active low and unused microswitches
M574 X1 U1 Y1 S1 ; Define active high microswitches
M558 P6 X0 Y0 Z1 H5 F120 T12000 ; Set Z probe type to unmodulated, the axes for which it is used and the probe + travel speeds
G31 P600 X0 Y0 Z0.148 ; Set Z probe trigger value, offset and trigger height

stephenc

went back and reviewed my Drives section (posted below) in config.g
do I need to do this for my 2nd Z?

Z16:16 ; for microstepping
Z800:800 ; for step per mm
Z800:800 ; for motor current
and so on?

–------------------------
; Drives
M569 P0 S0 ; Drive 0 goes forwards X
M569 P1 S0 ; Drive 1 goes forwards Y
M569 P2 S1 ; Drive 2 goes forwards Z
M569 P3 S0 ; Drive 3 goes forwards extruder T0
M569 P4 S0 ; Drive 4 goes forwards extruder T1
M569 P5 S1 ; Drive 5 goes forwards Uz
M569 P6 S1 ; Drive 6 goes forwards Ux
M350 X16 U16 Y16 Z16 E16:16 I1 ; Configure microstepping with interpolation
M92 X80 U80 Y53.33 Z800 E830:415 ; Set steps per mm
M566 X2000 U2000 Y2000 Z60 E1500:1500 ; Set maximum instantaneous speed changes (mm/min)
M203 X15000 U15000 Y15000 Z180 E6000:6000 ; Set maximum speeds (mm/min)
M201 X2500 U2500 Y2500 Z250 E1000:1000 ; Set accelerations (mm/s^2)
M906 X950 U950 Y950 Z800 E800:800 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

stephenc

can't remember if I've posted this video here… but this is how I home the 2 towers. After this homing, I manually confirm the two heads when move to same spot they both have the same distance between nozzle to top of bed surface. When printing, T0 (the one on the left and is the primary extruder) would print as expected in the correct layer height. But, T1 is problematic for some odd reason it appear to dive more in Z resulting the nozzle touching the bed surface perfectly thus nothing is extruding resulting in backpressure...

it's almost as if my G31 below as defined in my config.g is only applying to the left tower only...
G31 P600 X0 Y0 Z0.148 ; Set Z probe trigger value, offset and trigger height

https://youtu.be/PqQjZGIJ1rw

dc42

@stephenc:

went back and reviewed my Drives section (posted below) in config.g
do I need to do this for my 2nd Z?

Z16:16 ; for microstepping
Z800:800 ; for step per mm
Z800:800 ; for motor current
and so on?

No; but your M906 and M350 commands must come after the M584 command, so that they are applied to both the Z drivers.

Have you added M400 commands to your tool change files as per my previous response?

stephenc

yes I did add M400 though it doesn't appear to have any impact

my M584 is way up there under "general preferences" in the beginning of my config.g so both M906 and M350 have been placed after. or are you suggesting reversing this order?

dc42

The order you have is correct: M584 early, M350 and M906 later.

stephenc

in a very strange work around. I actually managed to get it to work. both print head print at the correct first layer now and more importantly same height

since my G31 has z offset of 0.15 all I did were:

update my homez.g after T1 touches FSR instead of it goes up 5mm i changed it to 5.15mm ( I kept T0 go up at 5mm)
After homez.g finish running, I ended up with Z5.30. now if I print this way I will end up with the issue I started this post with. so I went to console and did G92 Z5.15

then problem solved although this seems like a band aid solution…