SZP in touch mode

dc42

@CaiJonas when the nozzle just touches the bed, what is the distance between the probe coil and the bed? What is the bed surface?

gloomyandy

@CaiJonas You may find this thread over on discord of interest. I went through most of the process of setting things up to use touch mode for homing (including using two different sensor current settings for rough homing/scanning and actual touch homing). Note that these instructions are for the "old" sensitivity setting in beta.4 not the new one used in rc.1, but the procedure is the same. Also be aware that this is just how I decided to go through the various steps, I'm sure there are better ways to do some of it. There are a couple of folks over there that have followed this process and that seem to have it working. Please make sure that you follow the steps with caution, you are after all crashing the nozzle into your bed. Please also remember that the current touch implementation is experimental and may change in future releases. Use it with care!

https://discord.com/channels/711873626080804914/1345788631457202239

CaiJonas

@dc42

the distance is 4mm. If I reduce the distance I cannot use the touch mode because I get 999999 error when the nozzle touch the bed.

It is a textured pei plate with a magnetic foil to hold it.

Best Regards,
Cai

CaiJonas

@gloomyandy

Thank you very much for your help.

Unfortunately I cannot open the link. Could you please share again?

Best Regards,
Cai

jay_s_uk

@CaiJonas you may need to join our discord channel before being able to open the link
https://discord.gg/uS97Qs7

CaiJonas

@jay_s_uk great now it works. thank you very much

dc42

@CaiJonas 2mm sounds like a very small window, I would expect more. I presume you have tried using different drive levels (M558.2). If you set the minimum drive level that doesn't give a 999999 reading with the nozzle touching the bed, how high can you raise the nozzle before you get a 999999 reading?

The RC1+2 firmware at https://www.dropbox.com/scl/fo/y03luwmbypirbxncla3rk/AAJFLPFsVdFylemyhkXsAac?rlkey=7cq4svp4rzl2ztdffpzq2ghjk&dl=0 may provide a larger window than RC1 does.

CaiJonas

@dc42 this firmware is not making a difference.

May I ask some general question.

I calibrated the szp when the printer was preheated, otherwise it will not work
for what do I have to calibrate the probe: M558.1 K0. Is this needed before calbritating z = 0 with this command: G30 K0 S-2 Z-99999 ?
is there aother explanation for triggert hight and offset?

Best Regards
Cai

dc42

@CaiJonas the M558.1 calibration is needed (a) to set up the probe for use in scanning mode, and (b) to calibrate the trigger height and value if you execute a G30 command using the probe without putting it in touch mode. The calibration is not used when executing G30 in touch mode.

CaiJonas

@dc42
thanks for the fast answer. As I understood now, M558.1 calibration is needed if I would home z with the SZP and it is needed for the scanning.

I have an end switch at z limit to home and I use SZP in touch mode for z = 0 adjust.

I have played today after going back to 3.6.0 Release Candidate 1.

I recalibrate and have now M558.2 K0 S16 R133143.

Now I have a much bigger reading window/corridore. I don't know why not before.

In addition to that I do not need any more the turn around to adjust Z = 0.

My files now look like that:

; bed.g
T0                              ; se3lect tool1
M561 							; clear any bed transform
G90								; absolute postioning
G28                             ; home
G1 X60 Y5 Z3 F20000 			;
M558.3 K0 S1 V0.6 F100        	;
G30 K0 S-2 Z-99999              ;
M558.3 K0 S0                	;
G91								; absoluterelative postioning
G1 Z0.00                        ;
G92 Z0                          ;
G90								; absolute postioning
G29								; probe the bed and enable compensation

; mesh.g
T0                              ;
G90								; absolute postioning
G29 S2                          ; clear hight map
M557 X20:100 Y20:100 P10        ; Define grid for mesh bed compensation, origin in bed centre
G31 K0 Z2 Y15.5			    ; define probe 1 offsets and trigger height
M558.1 K0 S0.3                  ; Calibrate probe
G1 Z5                           ; Move up at end of calibration
G29 S0 K0                       ; Scan bed and create mesh

If needed where can I adjust the z offset after probing in touch mode?

best regards
Cai

dc42

@CaiJonas said in SZP in touch mode:

If needed where can I adjust the z offset after probing in touch mode?

M558.3 H parameter.

CaiJonas

@dc42

it's getting clearer. Thanks alot.

in which order do I have to put it

a)
M558.3 K0 S1 V0.6 F100 HXXX
G30 K0 S-2 Z-99999

or

b)
M558.3 K0 S1 V0.6 F100
G30 K0 S-2 Z-99999
M558.3 HXXX

and what about the S parameter in G30, do I need S-3 or S-2?

Best Regards
Cai

dc42

@CaiJonas both (a) and (b) will work. If you are using G30 to set Z=0 then don't use S-2 or S-3 in the G30 command. See https://docs.duet3d.com/en/User_manual/Reference/Gcodes#description-3.