Modified Ender-3 behaves strangely when starting to print

A Former User

This is my operational M671 on my ender-3 with dual lead screws

M671 X-25:260 Y115:115 S5 ; Z Axis lead screw locations in relation to the X axis

I have an operational config.g if you want a copy

Tanel_76

@Tanel_76 said in Modified Ender-3 behaves strangely when starting to print:

G28 ; home
G30 P0 X20 Y100 Z-99999 ; probe near a leadscrew, half way along Y axis
G30 P1 X180 Y100 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors

Hi,
I would like to see it, if possible.
I got the machine to properly do the x-gantry calibration, now
next thing to do is to the mesh compensation, after that I will try
to print the test cube again.

A Former User

Ender-3 dual leadscrew bed.g

G28                         ; home
G30 P0 X3 Y115 Z-99999      ; probe near the left lead-screw
G30 P1 X200 Y115 Z-99999 S2 ; probe near the right lead-screw 
G30 P0 X3 Y115 Z-99999      ; probe near the left lead-screw for the second time
G30 P1 X200 Y115 Z-99999 S2 ; probe near the right lead-screw for the second time
G91                         ; Relative positioning
G1 H2 Z5 F8000              ; Lift the Z axis relative to its current position
G90                         ; Absolute positioning
G1 X105 Y105 F6000          ; Go to the centre of the bed
G30                         ; Home the Z axis
G91                         ; Relative positioning
G1 Z5 F1000                 ; Lift the Z axis relative to its current position
G90                         ; Absolute positioning

Tanel_76

This post is deleted!

Tanel_76

Got the machine calibrated,
it's homing fine, when starting to print, it homes all,
then starts immediately move upwards, until Z145
then waits and starts to come back towards the bed slowly.

Strange.

Phaedrux

Post your homeall and homez.

Post your slicer start gcode.

Do you also have a start.g file in your system folder?

Tanel_76

Hi,

I threw the start.g out, after that the anomalies disappeared.

The only issue is now the Z height, I have calibrated and reset the (G92 Z0)
got the trigger height 2.4 and I have it in mu config.g
Still, when starting to print, the nozzle goes like 4.5mm downwards
from the calibrated height.

I deleted the slicer start code (the initial line in Cura)
just to see, what's happening.

Phaedrux

@Phaedrux said in Modified Ender-3 behaves strangely when starting to print:

Post your homeall and homez.

Tanel_76

Homeall
homez.g

I think these are pretty standard.

Veti

@Tanel_76 said in Modified Ender-3 behaves strangely when starting to print:

got the trigger height 2.4 and I have it in mu config.g

post you new config, you might have made a mistake

Tanel_76

The last conf file is here:
https://pastebin.com/npPJ2iSK

It's basically the same conf.g that I had uploaded earlier,
I just changed the M671 and also thermistor settings.

I copied the CaLviNx bed.g that he generously posted here.

When I start a print job, the nozzle goes down about 4.5mm,
I also recalibrated the Z height about 5 times,
the drop in Z height was constant every time.

Veti

@Tanel_76

so when you enter G28

and move to G0 Z0 then nozzle is above the bed?

Tanel_76

@CaLviNx said in Modified Ender-3 behaves strangely when starting to print:

I have an operational config.g if you want a copy

Is it possible to see the conf.g that you are using?

Tanel_76

@Veti said in Modified Ender-3 behaves strangely when starting to print:

@Tanel_76

so when you enter G28

and move to G0 Z0 then nozzle is above the bed?

No, and that's the strange thing. after resetting Z
I go G1 Z100 F400 and come down to G1 Z5 F400
the nozzle ploughs into the bed. When I move
down step by step, I see that the nozzle is above the
bed around Z55 which is not logical at all.

It's as if the G92 Z0 value is not entered correctly
and the Duet gets another value from somewhere,
which I can't find.

PS Im using this guide
https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#:~:text=In Duet Web Control%2C go,Save the file.

And Duet seems to have the same symptoms, as if when you forget the M500 command after resetting Z in Marlin.
I have to go to config-override.g and check that there are no G31 commands, when I'm near the printer again.

Veti

issue the G31 command to see if the duet got your offset set.

Phaedrux

Where are you sending G92 Z0? I don't see that anywhere in your homing files.

G90 ; absolute positioning
G1 X-5 Y-5 F6000 ; go to first bed probe point and home Z
G30 ; home Z by probing the bed

Also, from your homing files the G1 XY move makes no sense. It looks like it's just pushing it into the corner? The choice of an absolute negative value seems odd since your M208 minimum doesn't allow negative positions.

Regardless. You should choose a position that places the probe at the center of the bed.

Also, remove M564 H0 ; Allow unhomed movement from your config just to make sure it's not allowing moves that would otherwise fail. It can be hiding issues that should be fixed.

Tanel_76

@Phaedrux said in Modified Ender-3 behaves strangely when starting to print:

Where are you sending G92 Z0? I don't see that anywhere in your homing files.

When calibrating the Z height, I'm sending the command G92 Z0 to tell the firmware that the head is at Z=0,
it's not in the homing files.

I try to get access to the printer and go through the code once more.

Tanel_76

Got everything working, in the end I just ditched the line M564 H0
and everything else stayed as it was - and it's printing!

Thanks.