not able to get a good first layer using 3PL and bed mesh

moth4017

i have tried to get this first layer to print on a 320mm x 320mm bed . is a a square outline 300 x 300 0.3mm layer height 2.5mm wide ,

the result i get is that the left hand side doesnt stick to the bed and the right hand side has a great result. side by side pic below

i do the following leveling before printing

; homeall.g
echo "Home All.g "
				
M98 P"/sys/homey.g"  		;P define the parameter and is not part of the name
M98 P"/sys/homex.g"  		;P define the parameter and is not part of the name

M98 P"/macros/ProbePickUp"	; probe pick up

M98 P"/sys/homez.g" 		;P define the parameter and is not part of the name
M98 P"/macros/3PL"			; 3 point leveling;M98 P"/macros/3PL"			; 3 point leveling

M98 P"/sys/homez.g" 		;P define the parameter and is not part of the name
M98 P"/macros/3PL"			; 3 point leveling;M98 P"/macros/3PL"			; 3 point leveling

M98 P"/sys/homez.g" 		;P define the parameter and is not part of the name		
M98 P"/macros/3PL"			; 3 point leveling;M98 P"/macros/3PL"			; 3 point leveling


M98 P"/sys/homez.g" 		;P define the parameter and is not part of the name		
M98 P"/macros/3PL"			; 3 point leveling;M98 P"/macros/3PL"			; 3 point leveling
M98 P"/sys/homez.g" 		;P define the parameter and is not part of the name

;3PL
echo "3PL"
G30 P0 X2 Y2 Z-99999 		; probe near a leadscrew
G30 P1 X308 Y0 Z-99999 		; probe near a leadscrew
G30 P2 X155 Y282 Z-99999 S3 ; probe near a leadscrew and calibrate 3 motors
echo "3PL finished"
;M122						;send Diagnose to console

ive even done a macro to scan the bed after words using

echo "G30  s-1"
M98 P"/macros/ProbePickUP"	
G90 
G1 Z20 F24000	

G1 X20 Y25 F24000
G30  s-1
echo"FL"
G1 Z20 F24000	

G1 X310 Y25 F24000
G30  s-1
echo"FR"
G1 Z20 F24000	

G1 X310 Y280 F24000
G30  s-1
echo"RR"
G1 Z20 F24000	

G1 X20 Y280 F24000
G30  s-1
echo"RL"
G1 Z20 F24000	

G1 X155 Y155 F24000
G30  s-1
echo"Cen"
G1 Z25 F24000

results are like this

12/10/2022, 4:23:45 PM	Stopped at height 9.819 mm
Cen
ProbeDropOff
12/10/2022, 4:23:41 PM	Stopped at height 9.877 mm
RL
12/10/2022, 4:23:38 PM	Stopped at height 10.139 mm
RR
12/10/2022, 4:23:34 PM	Stopped at height 9.947 mm
FR
12/10/2022, 4:23:31 PM	Stopped at height 9.889 mm
FL

comments and ideas please

Phaedrux

Can you post an image of your heightmap being displayed?

What is in your homez?

Usually when the mesh isn't acting as expected, it's due to skew in the XY axis or tilt of the probe.

moth4017

@Phaedrux ```
; homez.g
echo "home Z.g "
G90 ;Set to Absolute Positioning
G1 F6000 X155 Y184 ; make sure X Y centreed
G30 F2000 ;Single Z-Probe
G1 Z18 F4000 ;move away a little
;M122 ;send Diagnose to console


no skew xy  already checked ,  probe looks fine i did a repeatability test  results "0.161 0.166 0.163 0.163 0.163 0.163 0.161 0.161 0.163 0.163, mean 0.162, deviation from mean 0.001"

![Capture1.PNG](/assets/uploads/files/1670646339712-capture1.png)

moth4017

@moth4017 ive tried a few height maps some with just 4 point and others with 36 point non seem to make a differance.

moth4017

@moth4017 by the way my bed is very flat i put a straight edge on it last night and could not get a 0.05 mm feeler gauge under it

Phaedrux

@moth4017 said in not able to get a good first layer using 3PL and bed mesh:

no skew xy already checked

The flat bed and the image showing some twist would suggest otherwise.

moth4017

@Phaedrux would you expect the bed mesh to compensate for this twist?

A Former User

This post is deleted!

moth4017

ok i can get a 4 point mesh to this

Phaedrux

I would suggest loosening the bolts for the XY stage, checking with a square and retightening.

moth4017

same result

moth4017

@moth4017 i made changes to get the 4 point mesh this level

moth4017

@moth4017 I just did a check to see if i could see my Z motors turning , i have a gear box's on the z axis so i should be able to see the steeper motor turning , but there is no movement

moth4017

@moth4017 start G code befor a print
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
M561 ; clear any bed transform
G28 ; home all axes
G29 ; mesh bed

Phaedrux

Is the gearbox having backlash?

You can send M122 to check if mesh is active. If you have G29 in your slicer start gcode it should be. Do you have a mesh.g file?

moth4017

@Phaedrux no back lash gear box belt driven ,

M122
=== Diagnostics ===
RepRapFirmware for Duet 3 Mini 5+ version 3.4.5 (2022-11-30 19:41:16) running on Duet 3 Mini5plus WiFi (standalone mode)
Board ID: 3R9YY-6T9RL-D65J0-40KMN-2UW2Z-RHYT0
Used output buffers: 1 of 40 (18 max)
=== RTOS ===
Static ram: 103652
Dynamic ram: 111396 of which 124 recycled
Never used RAM 23492, free system stack 126 words
Tasks: NETWORK(notifyWait,13.9%,237) HEAT(notifyWait,0.0%,320) Move(notifyWait,0.1%,265) CanReceiv(notifyWait,0.0%,942) CanSender(notifyWait,0.0%,328) CanClock(delaying,0.0%,339) TMC(notifyWait,1.2%,82) MAIN(running,83.9%,347) IDLE(ready,0.0%,30) AIN(delaying,0.8%,263), total 100.0%
Owned mutexes: WiFi(NETWORK)
=== Platform ===
Last reset 00:49:54 ago, cause: software
Last software reset at 2022-12-11 09:53, reason: User, GCodes spinning, available RAM 23540, slot 1
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x00000000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
Error status: 0x00
MCU revision 3, ADC conversions started 2994886, completed 2994886, timed out 0, errs 0
Step timer max interval 1476
MCU temperature: min 34.9, current 38.4, max 41.7
Supply voltage: min 23.6, current 23.9, max 24.2, under voltage events: 0, over voltage events: 0, power good: yes
Heap OK, handles allocated/used 99/11, heap memory allocated/used/recyclable 2048/1652/1440, gc cycles 0
Events: 0 queued, 0 completed
Driver 0: standstill, SG min 0, read errors 0, write errors 0, ifcnt 7, reads 9988, writes 68, timeouts 0, DMA errors 0, CC errors 0
Driver 1: standstill, SG min 0, read errors 0, write errors 0, ifcnt 9, reads 9986, writes 69, timeouts 0, DMA errors 0, CC errors 0
Driver 2: standstill, SG min 0, read errors 0, write errors 0, ifcnt 79, reads 10050, writes 6, timeouts 0, DMA errors 0, CC errors 0
Driver 3: standstill, SG min 0, read errors 0, write errors 0, ifcnt 104, reads 10042, writes 14, timeouts 0, DMA errors 0, CC errors 0
Driver 4: standstill, SG min 0, read errors 0, write errors 0, ifcnt 252, reads 10024, writes 32, timeouts 0, DMA errors 0, CC errors 0
Driver 5: standstill, SG min 0, read errors 0, write errors 0, ifcnt 251, reads 10023, writes 33, timeouts 0, DMA errors 0, CC errors 0
Driver 6: standstill, SG min 0, read errors 0, write errors 0, ifcnt 245, reads 10024, writes 32, timeouts 0, DMA errors 0, CC errors 0
Date/time: 2022-12-11 10:43:08
Cache data hit count 4294967295
Slowest loop: 68.52ms; fastest: 0.10ms
=== Storage ===
Free file entries: 10
SD card 0 detected, interface speed: 22.5MBytes/sec
SD card longest read time 4.9ms, write time 3.0ms, max retries 0
=== Move ===
DMs created 83, segments created 8, maxWait 173411ms, bed compensation in use: mesh, comp offset -0.065
=== MainDDARing ===
Scheduled moves 560, completed 560, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 2], CDDA state -1
=== AuxDDARing ===
Scheduled moves 0, completed 0, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters 2 -1 -1 -1, ordering errs 0
Heater 0 is on, I-accum = 0.1
Heater 1 is on, I-accum = 0.3
=== GCodes ===
Segments left: 0
Movement lock held by 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
Code queue is empty
=== Filament sensors ===
Extruder 0 sensor: ok
=== CAN ===
Messages queued 26948, received 0, lost 0, boc 0
Longest wait 0ms for reply type 0, peak Tx sync delay 0, free buffers 18 (min 18), ts 14971/0/0
Tx timeouts 0,0,14971,0,0,11976 last cancelled message type 4514 dest 127
=== Network ===
Slowest loop: 74.73ms; fastest: 0.00ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0)
HTTP sessions: 1 of 8
= WiFi =
Network state is active
WiFi module is connected to access point 
Failed messages: pending 0, notready 0, noresp 0
WiFi firmware version 1.27
WiFi MAC address f0:08:d1:02:a1:0b
WiFi Vcc 3.34, reset reason Power up
WiFi flash size 2097152, free heap 26440
WiFi IP address 192.168.0.19
WiFi signal strength -54dBm, mode 802.11n, reconnections 0, sleep mode modem
Clock register 00002002
Socket states: 0 0 0 0 0 0 0 0

;mesh.g
echo "mesh.g"
M561
M98 P"/macros/ProbePickUp"			; probe pick up; absolute positioning
G29 S0
M98 P"/macros/ProbeDropOff"			; probe pick up; absolute positioning

Phaedrux

@moth4017 said in not able to get a good first layer using 3PL and bed mesh:

bed compensation in use: mesh

Were you using your detailed mesh or the simplified 4 point? The movement could be incredibly hard to see with a mean error of -0.006mm

moth4017

@Phaedrux hi i was using the 4 point mesh , but the difference in nozel height from the bed was bad enough for the left hand side not to stick to the bed and the right hand side had a nice squish , see photo
above

moth4017

@moth4017, 1 step on my stepper motor moves the bed 0.025mm, using 1.8deg steppers

Phaedrux

@moth4017 said in not able to get a good first layer using 3PL and bed mesh:

@moth4017, 1 step on my stepper motor moves the bed 0.025mm, using 1.8deg steppers

If your single step distance is 0.025mm and the mesh points have a difference of ~0.006mm you would be depending on microstepping for position. Perhaps between that and the gear box there isn't enough actual movement happening?

Regardless, I still think there is an issue with skew.