Bug on 3.6.0? Layershifts & stuttering on arc travel moves

[CaiJonas]

Hello,

I had the problem that with activated option of "avoid perimeter" in orca and prusa slicer to see layershifts and suttering movements on arc travel moves. e.g. avoidung holes. My guess is a firmware bug. Anyone else have this problem?

Best Regards
Cai

[dc42]

@CaiJonas please share the GCode that the slicer generated for those travel moves.

[CaiJonas]

@dc42 adapter.gcode

[dc42]

@CaiJonas thanks for your example. Do you know whether firmware 3.5.4 exhibits the same behaviour?

[droftarts]

@CaiJonas Can you also post your config.g, and the response to M122, please. If you're using toolboards, please send M122 B#, where # is the CAN address of the toolboard.

Ian

[CaiJonas]

@dc42 as I can remember it was not the case before 3.6 but not 100% shure. If needed I can downgrade but I'm also not shure if the SZP will work with 3.5.4?

[CaiJonas]

@droftarts hope it's fine like the following

config.g

m122
=== Diagnostics ===
RepRapFirmware for Duet 3 Mini 5+ version 3.6.0-rc.2 (2025-03-31 12:16:33) running on Duet 3 Mini5plus WiFi (standalone mode)
Board ID: 8S6FD-V096U-D65J0-40KM0-4V03Z-RNJHW
Used output buffers: 3 of 40 (30 max)
=== RTOS ===
Static ram: 94764
Dynamic ram: 95664 of which 0 recycled
Never used RAM 51040, free system stack 198 words
Tasks: NETWORK(2,nWait 7,14.0%,207) LASER(5,nWait 7,0.0%,235) HEAT(3,nWait 6,0.0%,350) Move(4,nWait 6,0.0%,353) TMC(4,delaying,0.8%,99) CanReceiv(6,nWait 1,0.0%,794) CanSender(5,nWait 7,0.0%,336) CanClock(7,delaying,0.0%,348) MAIN(1,running,84.1%,661) IDLE(0,ready,0.2%,29) USBD(3,blocked,0.0%,147) AIN(4,delaying,0.8%,255), total 100.0%
Owned mutexes: WiFi(NETWORK)
=== Platform ===
Last reset 00:04:33 ago, cause: software
Last software reset at 2025-04-08 14:43, reason: User, Gcodes spinning, available RAM 40716, slot 1
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x00489000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
=== Storage ===
Free file entries: 20
SD card 0 detected, interface speed: 22.5MBytes/sec
SD card longest read time 3.7ms, write time 0.0ms, max retries 0
=== Move ===
Segments created 0, maxWait 0ms, bed comp in use: none, height map offset 0.000, hiccups added 0/0 (0.00/0.00ms), max steps late 0, ebfmin 0.00, ebfmax 0.00
Pos req/act/dcf: 0.00/0/0.00 0.00/0/0.00 0.00/0/0.00
No step interrupt scheduled
Driver 0: standstill, SG min 8, r/w errs 0/1, ifcnt 46, reads/writes 14381/13, timeouts 0, DMA errs 0, CC errs 0
Driver 1: standstill, SG min 160, r/w errs 0/1, ifcnt 173, reads/writes 14379/15, timeouts 0, DMA errs 0, CC errs 0
Driver 2: standstill, SG min 14, r/w errs 0/1, ifcnt 171, reads/writes 14379/15, timeouts 0, DMA errs 0, CC errs 0
Driver 3: standstill, SG min 2, r/w errs 0/1, ifcnt 46, reads/writes 14380/13, timeouts 1, DMA errs 0, CC errs 0, failedOp 0x71
Driver 4: standstill, SG min 0, r/w errs 0/1, ifcnt 46, reads/writes 14381/13, timeouts 0, DMA errs 0, CC errs 0
Driver 5: not present
Driver 6: not present
=== DDARing 0 ===
Scheduled moves 0, completed 0, LaErrors 0, Underruns [0, 0, 0]
Segments left 0, axes/extruders owned 0x00000803, drives owned 0x00000803
Code queue is empty
=== DDARing 1 ===
Scheduled moves 0, completed 0, LaErrors 0, Underruns [0, 0, 0]
Segments left 0, axes/extruders owned 0x00000000, drives owned 0x00000000
Code queue is empty
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters -1 -1 -1 -1, ordering errs 0
Heater 0 is on, I-accum = 0.6
Heater 1 is on, I-accum = 0.2
=== GCodes ===
Movement locks held by null, null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
SBC is idle in state(s) 0
Daemon is idle in state(s) 0
Aux2 is idle in state(s) 0
Autopause is idle in state(s) 0
File2 is idle in state(s) 0
Queue2 is idle in state(s) 0
=== CAN ===
Messages queued 2398, received 2196, lost 0, ignored 0, errs 1, boc 0
Longest wait 2ms for reply type 6031, peak Tx sync delay 387, free buffers 26 (min 25), ts 1298/1297/0
Tx timeouts 0,0,0,0,0,0
=== Network ===
Slowest loop: 30.42ms; fastest: 0.00ms
Responder states: MQTT(0) HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0)
HTTP sessions: 2 of 8
=== WiFi ===
Interface state: active
Module is connected to access point
Failed messages: pending 0, notrdy 0, noresp 0
Firmware version 2.2.1
Module reset reason: Power up, Vcc 3.39, flash size 2097152, free heap 39380
MAC address *************
IP address ************
Signal strength -65dBm, channel 6, mode 802.11n, reconnections 0
Clock register 00002002
Socket states: 0 0 0 0 0 0 0 0

M122 B0
=== Diagnostics ===
RepRapFirmware for Duet 3 Mini 5+ version 3.6.0-rc.2 (2025-03-31 12:16:33) running on Duet 3 Mini5plus WiFi (standalone mode)
Board ID: 8S6FD-V096U-D65J0-40KM0-4V03Z-RNJHW
Used output buffers: 1 of 40 (32 max)
=== RTOS ===
Static ram: 94764
Dynamic ram: 95664 of which 0 recycled
Never used RAM 51040, free system stack 198 words
Tasks: NETWORK(2,ready,20.2%,207) LASER(5,nWait 7,0.0%,235) HEAT(3,nWait 6,0.0%,350) Move(4,nWait 6,0.0%,353) TMC(4,nWait 6,0.8%,99) CanReceiv(6,nWait 1,0.0%,794) CanSender(5,nWait 7,0.0%,336) CanClock(7,delaying,0.0%,348) MAIN(2,running,76.0%,661) IDLE(0,ready,2.1%,29) USBD(3,blocked,0.0%,147) AIN(4,delaying,0.8%,255), total 100.0%
Owned mutexes: WiFi(NETWORK) HTTP(MAIN)
=== Platform ===
Last reset 00:05:47 ago, cause: software
Last software reset at 2025-04-08 14:43, reason: User, Gcodes spinning, available RAM 40716, slot 1
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x00489000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
=== Storage ===
Free file entries: 20
SD card 0 detected, interface speed: 22.5MBytes/sec
SD card longest read time 3.4ms, write time 0.0ms, max retries 0
=== Move ===
Segments created 0, maxWait 0ms, bed comp in use: none, height map offset 0.000, hiccups added 0/0 (0.00/0.00ms), max steps late 0, ebfmin 0.00, ebfmax 0.00
Pos req/act/dcf: 0.00/0/0.00 0.00/0/0.00 0.00/0/0.00
No step interrupt scheduled
Driver 0: standstill, SG min 8, r/w errs 0/0, ifcnt 46, reads/writes 927/0, timeouts 0, DMA errs 0, CC errs 0
Driver 1: standstill, SG min 160, r/w errs 0/0, ifcnt 173, reads/writes 927/0, timeouts 0, DMA errs 0, CC errs 0
Driver 2: standstill, SG min 14, r/w errs 0/0, ifcnt 171, reads/writes 927/0, timeouts 0, DMA errs 0, CC errs 0
Driver 3: standstill, SG min 2, r/w errs 0/0, ifcnt 46, reads/writes 927/0, timeouts 0, DMA errs 0, CC errs 0
Driver 4: standstill, SG min 0, r/w errs 0/0, ifcnt 46, reads/writes 927/0, timeouts 0, DMA errs 0, CC errs 0
Driver 5: not present
Driver 6: not present
=== DDARing 0 ===
Scheduled moves 0, completed 0, LaErrors 0, Underruns [0, 0, 0]
Segments left 0, axes/extruders owned 0x00000803, drives owned 0x00000803
Code queue is empty
=== DDARing 1 ===
Scheduled moves 0, completed 0, LaErrors 0, Underruns [0, 0, 0]
Segments left 0, axes/extruders owned 0x00000000, drives owned 0x00000000
Code queue is empty
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters -1 -1 -1 -1, ordering errs 0
Heater 0 is on, I-accum = 0.5
Heater 1 is on, I-accum = 0.2
=== GCodes ===
Movement locks held by null, null
HTTP is ready with "M122 B0" in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
SBC is idle in state(s) 0
Daemon is idle in state(s) 0
Aux2 is idle in state(s) 0
Autopause is idle in state(s) 0
File2 is idle in state(s) 0
Queue2 is idle in state(s) 0
=== CAN ===
Messages queued 155, received 142, lost 0, ignored 0, errs 0, boc 0
Longest wait 0ms for reply type 0, peak Tx sync delay 6, free buffers 26 (min 25), ts 83/83/0
Tx timeouts 0,0,0,0,0,0
=== Network ===
Slowest loop: 21.25ms; fastest: 0.08ms
Responder states: MQTT(0) HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0)
HTTP sessions: 2 of 8
=== WiFi ===
Interface state: active
Module is connected to access point
Failed messages: pending 0, notrdy 0, noresp 0
Firmware version 2.2.1
Module reset reason: Power up, Vcc 3.39, flash size 2097152, free heap 39168
MAC address *************
IP address ************
Signal strength -65dBm, channel 6, mode 802.11n, reconnections 0
Clock register 00002002
Socket states: 0 0 0 0 0 0 0 0

[dc42]

@CaiJonas the SZP doesn't work with 3.5.4.

[CaiJonas]

@dc42 ok, then I can't roll back, sorry

[dc42]

@CaiJonas the stuttering movements appear to be a feature of the moves generated. They are not arc moves, they are a sequence of line segments. Here's an example from line 2270 of your example file:

G1 X60.133 Y46.575 E.6074 ; perimeter
G1 E-.5 F3000 ; retract
G1 X60.509 Y46.911 F18000
G1 X75.371 Y60.871 ; move to first infill point
G1 X75.561 Y61.029 ; move to first infill point
G1 X75.728 Y61.145 ; move to first infill point
G1 X79.425 Y63.53 ; move to first infill point
G1 X79.396 Y63.585 ; move to first infill point
G1 X78.911 Y63.328 ; move to first infill point
G1 E.5 F3000 ;  ; unretract
;TYPE:Internal solid infill
;WIDTH:0.420424
G1 F12000
M106 S81 ; enable fan
G1 X77.989 Y64.25 E.0389 ; infill

The commanded speed is F18000 but RRF can't maintain that speed at the boundaries between moves because the direction changes between the moves would cause the jerk limit to be exceeded. So RRF reduces the speed at the boundary to a value that doesn't cause the jerk limit to be exceeded.

It's possible that you are getting movement queue underruns, which would contribute to the jerky movement. The M122 report you published doesn't show any, but perhaps you didn't run M122 after a print.

If you are getting layer shifts then it's likely that you have the maximum speed or acceleration or jerk set higher than the motor can handle at the current you are using. You can try increasing XY motor currents, if the motor rated current allows. This won't help if the speed is high enough for the torque to start reducing. You can use the calculator at https://www.reprapfirmware.org/emf.html to estimate that speed.

[CaiJonas]

@dc42

mhh I'm not shure if this is the root cause.

I played a little and tried the following without any problems:

• same .stl file
• increased print and travel speed to 300mm/s
• activated avoid crossing perimeter
• print speed is not limited by extrusion rate to guarantee 300 mm/s

m122 after print:

m122
=== Diagnostics ===
RepRapFirmware for Duet 3 Mini 5+ version 3.6.0-rc.2 (2025-03-31 12:16:33) running on Duet 3 Mini5plus WiFi (standalone mode)
Board ID: 8S6FD-V096U-D65J0-40KM0-4V03Z-RNJHW
Used output buffers: 2 of 40 (25 max)
=== RTOS ===
Static ram: 94764
Dynamic ram: 95644 of which 0 recycled
Never used RAM 40308, free system stack 130 words
Tasks: NETWORK(2,nWait 7,17.1%,191) LASER(5,nWait 7,0.2%,169) HEAT(3,nWait 6,0.1%,329) Move(4,nWait 6,2.5%,249) TMC(4,nWait 6,1.0%,65) CanReceiv(6,nWait 1,0.0%,771) CanSender(5,nWait 7,0.0%,336) CanClock(7,delaying,0.0%,348) MAIN(1,running,77.9%,661) IDLE(0,ready,0.3%,29) USBD(3,blocked,0.0%,147) AIN(4,delaying,0.9%,255), total 100.0%
Owned mutexes:
=== Platform ===
Last reset 00:21:19 ago, cause: software
Last software reset at 2025-04-23 09:37, reason: User, Gcodes spinning, available RAM 39248, slot 2
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x00000000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
=== Storage ===
Free file entries: 20
SD card 0 detected, interface speed: 22.5MBytes/sec
SD card longest read time 12.1ms, write time 49.4ms, max retries 0
=== Move ===
Segments created 448, maxWait 46510ms, bed comp in use: mesh, height map offset 0.000, hiccups added 131/0 (0.00/0.00ms), max steps late 1, ebfmin 0.00, ebfmax 0.00
Pos req/act/dcf: 0.00/0/0.00 0.00/0/0.00 54466.00/54466/0.00
No step interrupt scheduled
Driver 0: standstill, SG min 0, r/w errs 0/1, ifcnt 68, reads/writes 1424/16, timeouts 0, DMA errs 0, CC errs 0
Driver 1: standstill, SG min 0, r/w errs 0/1, ifcnt 158, reads/writes 1402/38, timeouts 0, DMA errs 0, CC errs 0
Driver 2: standstill, SG min 0, r/w errs 0/1, ifcnt 157, reads/writes 1400/39, timeouts 0, DMA errs 0, CC errs 0
Driver 3: standstill, SG min 0, r/w errs 0/1, ifcnt 68, reads/writes 1423/16, timeouts 0, DMA errs 0, CC errs 0
Driver 4: standstill, SG min 0, r/w errs 0/1, ifcnt 68, reads/writes 1424/16, timeouts 0, DMA errs 0, CC errs 0
Driver 5: not present
Driver 6: not present
=== DDARing 0 ===
Scheduled moves 86854, completed 86854, LaErrors 0, Underruns [0, 0, 0]
Segments left 0, axes/extruders owned 0x00000803, drives owned 0x00000803
Code queue is empty
=== DDARing 1 ===
Scheduled moves 0, completed 0, LaErrors 0, Underruns [0, 0, 0]
Segments left 0, axes/extruders owned 0x00000000, drives owned 0x00000000
Code queue is empty
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters -1 -1 -1 -1, ordering errs 0
=== GCodes ===
Movement locks held by null, null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
SBC is idle in state(s) 0
Daemon is idle in state(s) 0
Aux2 is idle in state(s) 0
Autopause is idle in state(s) 0
File2 is idle in state(s) 0
Queue2 is idle in state(s) 0
=== CAN ===
Messages queued 11374, received 10435, lost 0, ignored 0, errs 1, boc 0
Longest wait 3ms for reply type 6061, peak Tx sync delay 460, free buffers 26 (min 25), ts 6066/6065/0
Tx timeouts 0,0,0,0,0,0
=== Network ===
Slowest loop: 111.43ms; fastest: 0.00ms
Responder states: MQTT(0) HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0)
HTTP sessions: 1 of 8
=== WiFi ===
Interface state: active
Module is connected to access point 
Failed messages: pending 0, notrdy 0, noresp 0
Firmware version 2.2.1
Module reset reason: Power up, Vcc 3.39, flash size 2097152, free heap 37532
MAC address XXXXXXXXXX
IP address 192.168.X[adapter (1).gcode](/assets/uploads/files/1745395364873-adapter-1.gcode) .XXX
Signal strength -55dBm, channel 6, mode 802.11n, reconnections 0
Clock register 00002002
Socket states: 0 0 0 0 0 0 0 0

config file:

; Configuration file for Duet 3 Mini 5+ (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Wed Jan 12 2022 22:48:14 GMT+0100 (Mitteleurop ische Normalzeit)

; General preferences
G4 S2																	; wait for expansion boards to start
M575 P1 S1 B57600														; enable support for PanelDue
G90																		; send absolute coordinates...
M83																		; ...but relative extruder moves
M550 P"COREXY"															; set printer name
M669 K1																	; select CoreXY mode

; Network
M552 S1		P"XXXXXXXXXXXXXXXX"										; enable network
M586 P0 S1																; enable HTTP

; Drives
M569	P0.0 S0	D2		 			 								    ; physical drive 0.0 goes forwards
M569	P0.1 S1	D2		 							    				; physical drive 0.1 goes forwards
M569	P0.2 S1	D2				    									; physical drive 0.2 goes forwards
M569	P0.3 S0	D2 		 							    				; physical drive 0.3 goes forwards
M569	P0.4 S1	D2 		 					        					; physical drive 0.3 goes forwards
M584	X0.1	Y0.2	Z0.3:0.4	E0.0								; set drive mapping
M350 	X16 	Y16 	Z16 		E16 	I1							; configure microstepping with interpolation
M92		X200	Y200	Z480		E562								; set steps per Z3200 E591
M201 	X6000	Y6000	Z900		E6000								; Set print accelerations (mm/s^2) Z1200
M201.1	X600	Y600	Z120		E6000								; Set accelerations for special moves (mm/s^2)
M204	P6000	T6000													;
M203 	X18000	Y18000	Z12000		E3000								; Set maximum speeds (mm/min) Z1200
M566	X900	Y900	Z900		E600	P1							; set maximum instantaneous speed changes (mm/min)
M906 	X900	Y900	Z1000		E800	I15							; set motor currents (mA) and motor idle factor in per cent
M84		S60																; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 S1														; set axis minima
M208 X120 Y120 Z113.5	 S0												; set axis maxima
		
; Endstops
M574 X1 S4																; configure sensorless endstop for low end on X
M574 Y1 S4																; configure sensorless endstop for low end on Y
M574 Z2 S1 P"io4.in"													; configure switch-type (e.g. microswitch) endstop for low end on Z via pin io0.in M574 Z1 S1 P"io4.in"
M915 X	Y	S8	R0	F0	H400											; Sensorless homing

; Scanning Z probe
M558 K0 P11 C"120.i2c.ldc1612" F12000 T12000							; configure SZP as probe 1, type 11, on CAN address 120
M308 A"SZP coil" S10 Y"thermistor" P"120.temp0"							; thermistor on SZP coil
G31 K0 Z2 Y15.5				       										; define probe 1 offsets and trigger height
M558.2 K0 S15 R135000													; set drive current and reading offset	18, offset is 139427
M557 X20:100 Y20:100 S10												; Define mesh grid for probe 1 (overwrites probe 0 mesh grid)

; Sensors
M308 S0 P"temp0" Y"thermistor" A"Heated Bed" T100000 B4725 C7.06e-8		; configure sensor #0
M308 S1 P"temp1" Y"thermistor" A"Nozzle" T100000 B4388 C7.06e-8			; configure sensor #1

; Heaters
M950 H0 C"out0" T0														; create bed heater output on out0 and map it to sensor 0
M143 H0 P0 T0 C0 S115 A0												; configure heater monitor #0 for heater #0
M307 H0 R1.086 K0.828:0.000 D3.71 E1.35 S1.00 B0						; disable bang-bang mode for the bed heater and set PWM limit
M950 H1 C"out2" T1														; create nozzle heater output on out1 and map it to sensor 1
M143 H1 P0 T1 C0 S285 A0												; configure heater monitor #0 for heater #1
M307 H1 R3.289 K0.416:0.048 D4.18 E1.35 S1.00 B0 V24.2					; configure model of heater #1

; Heated beds
M140 P0 H0																; configure heated bed #0

; Fans
M950 F0 C"out5" Q500													; create fan 0 on pin out3 and set its frequency
M106 P0 S0 H-1															; set fan 0 value. Thermostatic control is turned off
M950 F1 C"out1" Q500													; create fan 1 on pin out4 and set its frequency
M106 P1 S1 H1 T45														; set fan 1 value. Thermostatic control is turned on
M950 F2 C"out6" Q500													; create fan 2 on pin out3 and set its frequency
M106 P2 S0 H1 T45														; set fan 2 value. Thermostatic control is turned off
M950 F3 C"!out4+out4.tach" Q25000										; create fan 3 on pin out4 and set its frequency												
M106 P3 S1 X0.45 H1 T50													; set fan 3 value. Thermostatic control is turned off
	
; Tools
M563 P0 D0 H1 F0														; 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

; Accelerometer
M955 P120.0 I24															; Add accelerometer on SZP with CAN address 120 and specify orientation

; Custom settings are not defined
M501																	;

print file
adapter (1).gcode

Are you sure it's related to max speed?

Best Regards
Cai

[CaiJonas]

@CaiJonas @dc42

I have to apologize, I'm wrong. I printed another part with exact same settings and there the layershift occurs again.

Is there a proper way to define the max speed with defined jerk an acceleration settings?

Best Regards
Cai