Bug in G53 calculation with axis compensation and tool offset

shugo1110

Hi there,

When I run G53 with M579 and a non-zero tool offset the resulting position adds the axes compensation ratio of the tool offset. To demonstrate what I mean, I wrote a little macro:

M579 X1.01488 Y1.0067 ; axis compensation
T0 P0 ; select first Tool

G10 P0 X0 Y0 ; set Tool offset to zero

G53 G1 X150 Y150
G4 S2
echo "X:" ^ move.axes[0].machinePosition ^ " Y:" ^ move.axes[1].machinePosition
; X = 150*1.01488 = 152.232
; Y = 150*1.0067 = 151.005


G10 P0 X-0.5 Y62 ; set Tool offset to non-zero

G53 G1 X150 Y150
G4 S2
echo "X:" ^ move.axes[0].machinePosition ^ " Y:" ^ move.axes[1].machinePosition

; X = (-0.5+150)*1.01488 - (-0.5) = 152.225
; Y = (62+150)*1.0067 - 62 = 151.421

When I run G53 i would expect the same position even when i change the tool. It is not possible to go the a specific point. When I run the following code, the tool head is colliding with the axes:

M564 S0 ; allow movement outside boundaries (i need it sometimes)
G53 G1 X{move.axes[0].max} Y{move.axes[1].max}

Specs:

I have a Duet 3MB6HC with two 3HC in standalone mode.
The printer is running in CoreXY-mode (M669 K1) so i need to use the M579 Command to compensate the axes.
I have multiple tools attached and each of them has its own offset.

To strip down my complete configuration i reproduced the bug with the following configuration (using the ConfigTool) :

; Configuration file for Duet 3 MB 6HC (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.16 on Fri Jun 30 2023 10:21:33 GMT+0200 (Mitteleuropäische Sommerzeit)

; General preferences
M80 C"pson"
M575 P1 S1 B57600                                             ; enable support for PanelDue
G90                                                           ; send absolute coordinates...
M83                                                           ; ...but relative extruder moves
M550 P"Konus2264"                                             ; set printer name
M669 K1                                                       ; select CoreXY mode

; Wait a moment for the CAN expansion boards to start
G4 S2

; Network
M552 P0.0.0.0 S1                                              ; enable network and acquire dynamic address via DHCP
M586 P0 S1                                                    ; enable HTTP
M586 P1 S1                                                    ; enable FTP
M586 P2 S0                                                    ; disable Telnet

; Drives
M569 P0.4 S0                                                  ; physical drive 0.4 goes backwards
M569 P0.5 S0                                                  ; physical drive 0.5 goes backwards
M569 P0.0 S1                                                  ; physical drive 0.0 goes forwards
M569 P1.0 S1                                                  ; physical drive 1.0 goes forwards
M584 X0.4 Y0.5 Z0.0 E1.0                                      ; set drive mapping
M350 X256 Y256 Z256 E256 I0                                   ; configure microstepping without interpolation
M92 X1280.00 Y1280.00 Z25600.00 E6530.73                      ; set steps per mm
M566 X3000.00 Y3000.00 Z180.00 E1200.00                       ; set maximum instantaneous speed changes (mm/min)
M203 X12000.00 Y12000.00 Z300.00 E3000.00                     ; set maximum speeds (mm/min)
M201 X3000.00 Y3000.00 Z20.00 E10000.00                       ; set accelerations (mm/s^2)
M906 X800 Y800 Z1200 E1000 I20                                ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                                       ; Set idle timeout

; Axis Limits
M208 X-27 Y-82 Z0 S1                                          ; set axis minima
M208 X325.7 Y312.6 Z370 S0                                    ; set axis maxima

; Endstops
M574 X2 S1 P"!io2.in"                                         ; configure switch-type (e.g. microswitch) endstop for high end on X via pin !io2.in
M574 Y2 S1 P"!io1.in"                                         ; configure switch-type (e.g. microswitch) endstop for high end on Y via pin !io1.in
M574 Z1 S2                                                    ; configure Z-probe endstop for low end on Z

; Z-Probe
M950 S0 C"io7.out"                                            ; create servo pin 0 for BLTouch
M558 P9 C"io7.in" H15 F240 T600                               ; set Z probe type to bltouch and the dive height + speeds
G31 P500 X29.5 Y-2 Z3.5                                       ; set Z probe trigger value, offset and trigger height
M557 X30:285 Y-67:255 S15                                     ; define mesh grid

; Heaters
M308 S0 P"temp0" Y"thermistor" T98801 B4185                   ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" T0                                            ; create bed heater output on out0 and map it to sensor 0
M307 H0 B1 S1.00                                              ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0                                                       ; map heated bed to heater 0
M143 H0 S130                                                  ; set temperature limit for heater 0 to 130C
M308 S1 P"1.temp0" Y"thermistor" T100000 B4725 C7.06e-8       ; configure sensor 1 as thermistor on pin 1.temp0
M950 H1 C"1.out0" T1                                          ; create nozzle heater output on 1.out0 and map it to sensor 1
M307 H1 B0 S1.00                                              ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S275                                                  ; set temperature limit for heater 1 to 275C

; Fans
M950 F0 C"1.out3" Q100                                        ; create fan 0 on pin 1.out3 and set its frequency
M106 P0 C"T0 Heatsink" S1 H1 T70                              ; set fan 0 name and value. Thermostatic control is turned on
M950 F1 C"1.out6" Q50                                         ; create fan 1 on pin 1.out6 and set its frequency
M106 P1 C"T0 Nozzle" S0 H-1                                   ; set fan 1 name and value. Thermostatic control is turned off

; Tools
M563 P0 S"T0" D0 H1 F2:1                                      ; define tool 0
G10 P0 X0 Y0 Z0                                               ; set tool 0 axis offsets
G10 P0 R0 S0                                                  ; set initial tool 0 active and standby temperatures to 0C

; Custom settings are not defined

; Miscellaneous
M501                                                          ; load saved parameters from non-volatile memory
M911 S22 R23 P"M913 X0 Y0 U0 G91 M83 G1 Z0.3 E-5 F1000 G1 Z3" ; set voltage thresholds and actions to run on power loss

Thanks for your time.

dc42

@shugo1110 thanks for reporting this. I created https://github.com/Duet3D/RepRapFirmware/issues/883.

Which firmware version are you running? If I provide a new firmware binary with a likely fix in it, would you be able to test it?

dc42 created this issue in Duet3D/RepRapFirmware

closed Bug in G53 calculation with axis compensation and tool offset #883

shugo1110

@dc42

3.5.0-beta.3 on 6MB and 3HC. The problem existed already in earlier firmwares but at that time i couldn't figured out why.

Yes i would able to test it.

Thanks

dc42

@shugo1110 thanks. Please try the build at https://www.dropbox.com/sh/vxzb68lep3fg9yj/AAAK0vYIrOd2oR7HlotdOPcQa?dl=0. This is based on 3.5.0-beta.4 so you should upgrade your 3HC boards to that version.

shugo1110

@dc42 @T3P3Tony

Sorry for the delay, i had to fix some beta.4-related problems with my configuaration (Led Strip, invalid value for parameter '-')

When I do a G53 G1 X150 Y150 the position is now independend of the current tool offset. This works fine.

Just for reference: The resulting machine-position is not 150 as i expected; it is 150*axis-compensation-factor. In the example in my first post:

...
G53 G1 X150 Y150
G4 S2; wait
echo "X:" ^ move.axes[0].machinePosition ^ " Y:" ^ move.axes[1].machinePosition
; X:152.232 Y:151.005

I don't know if it's correct, maybe this is a design decision. But when i want to move to the highest edge i have to do a

G53 G1 X{move.axes[0].max/1.01488} Y{move.axes[1].max/1.0067}

Thanks

T3P3Tony

@shugo1110 Thanks for testing and confirming the fix!