How to measure leadsrew coordinates

[MartinNYHC]

Next step is to configure bed levelling with three SFU1204. I'm wondering how I have to measure the position of the leadscrews. From which position to the center of the leadscrew?

Beside of that I'm quite sure that I need some additional help from you guys. I can smell that already

Thanks, Martin

[engikeneer]

@MartinNYHC overall you want the positions relative to the 0,0 point of your printer. I did mine by lining up the nozzle with centre of the lead screw in one axis (if they're on the sides if the bed it will be the Y), then used a ruler to measure the x distance from the nozzle. With that plus the position given in the web control you have the XY position of the leadscrew relative to 0,0.

Depending on how uber accurate you're going for, you probably only need to get the positions right to a couple of mm. The biggest thing is to make sure you get them in the correct order when putting the positions in the config!

[MartinNYHC]

OK, but then it would be easier to move the nozzle to 0,0 and measure the distance. Isn't it? Will try that now.

[Veti]

move the nozzle as close to the leadscrew as you can using g code.
then look up the current position in the web ui.

now measure the distance from the nozzle to the leadscrew and adjust coordinates with your measurements.

[MartinNYHC]

@Veti That's what I did

M584 X0.0 Y0.1 Z0.3:0.4:0.5 E0.2                         ; set drive mapping
M671 X-25:-32:398 Y360:10:202 S5			             ; Set up three Z-axis location

Let's see what happens now.

[MartinNYHC]

My next problem is that when I do a G32, probe points are not equal to the points defined with G30 in bed.c although i do a G90 at the beginning.

Here the config I have so far...

config.g

; General preferences
G90                                                      ; send absolute coordinates...
M83                                                      ; ...but relative extruder moves
M550 P"duet3"                                            ; set printer name
M669 K1                                                  ; select CoreXY mode

; Drives                                                 ; X:0.0, Y:0.1, E:0.2, Z_left_rear:0.3, Z_left_front:0.4, Z_right:0.5
M569 P0.0 S0                                             ; physical drive 0.0 goes forwards
M569 P0.1 S0                                             ; physical drive 0.1 goes forwards
M569 P0.2 S0                                             ; physical drive 0.2 goes forwards
M569 P0.3 S0                                             ; physical drive 0.3 goes forwards
M569 P0.4 S1                                             ; physical drive 0.4 goes forwards
M569 P0.5 S1                                             ; physical drive 0.5 goes forwards

M584 X0.0 Y0.1 Z0.3:0.4:0.5 E0.2                         ; set drive mapping
M350 X16 Y16 Z16 E16 I1                                  ; configure microstepping with interpolation
M92 X200.00 Y200.00 Z400.00 E405.18                      ; set steps per mm
M566 X600.00 Y600.00 Z24.00 E120.00                      ; set maximum instantaneous speed changes (mm/min)
M203 X18000.00 Y18000.00 Z6000.00 E1200.00               ; set maximum speeds (mm/min)
M201 X3000.00 Y3000.00 Z100.00 E5000.00                  ; set accelerations (mm/s^2)
M906 X1600 Y1600 Z1600 E1600 I30                         ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                                  ; Set idle timeout

; Three axis setup - leadscrew positions
M671 X-25:-32:398 Y360:10:202 S5			             ; Set up three Z-axis location

; Axis Limits
M208 X0 Y0 Z0 S1                                         ; set axis minima
M208 X330 Y330 Z450 S0                                   ; set axis maxima

; Endstops
M574 X1 S1 P"io3.in"                                     ; configure active-high endstop for low end on X via pin io1.in
M574 Y2 S1 P"io4.in"                                     ; configure active-high endstop for high end on Y via pin io2.in

; Z-Probe
M950 S0 C"io7.out"                                       ; create servo pin 0 for BLTouch
M558 P9 C"^io7.in" H10 F500 T6000                         ; set Z probe type to bltouch and the dive height + speeds
;G31 P500 X36.47 Y14 Z5                                   ; set Z probe trigger value, offset and trigger height
G31 P500 X0 Y0 Z10                                   ; set Z probe trigger value, offset and trigger height
M557 X15:300 Y50:350 S57                                   ; define mesh grid

; Heaters
M308 S0 P"temp1" Y"thermistor" T95000 B3950              ; configure sensor 0 as thermistor on pin temp1
M950 H0 C"out2" T0                                       ; create bed heater output on out1 and map it to sensor 0
M307 H0 B0 S1.00                                         ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0                                                  ; map heated bed to heater 0
M143 H0 S120                                             ; set temperature limit for heater 0 to 120C
M308 S1 P"temp0" Y"thermistor" T500000 B4723 C1.19622e-7 ; configure sensor 1 as thermistor on pin temp0
M950 H1 C"out3" T1                                       ; create nozzle heater output on out2 and map it to sensor 1
M307 H1 B0 S1.00                                         ; disable bang-bang mode for heater  and set PWM limit

; Fans
M950 F0 C"out4" Q500                                     ; create fan 0 on pin out4 and set its frequency
M106 P0 S0 H-1                                           ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"out5" Q500                                     ; create fan 1 on pin out5 and set its frequency
M106 P1 S1 H-1                                           ; set fan 1 value. Thermostatic control is turned on
M950 F2 C"out6" Q500                                     ; create fan 2 on pin out6 and set its frequency
M106 P2 S0.3 H-1                                         ; set fan 2 value. Thermostatic control is turned off
M950 F3 C"out7" Q500                                     ; create fan 3 on pin out7 and set its frequency
M106 P3 S1 H-1                                           ; set fan 3 value. Thermostatic control is turned off

; Tools
M563 P0 S"Hotend" D0 H1 F0                               ; define tool 0
G10 P0 X13 Y20 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
M575 P1 S1 B115200                                       ; enable support for PanelDue
M501                                                     ; load saved parameters from non-volatile memory
T0                                                       ; select first tool

bed.g

M291 P"Probing mesh grid process started" R"Probing.." S1 T2
M561                                    ; clear any bed transform
G90                                             ; absolute positioning bb

G1 Z20 F4000                            ; Making sure we're not going to hit the side of glass
M400                                            ;Wait for move to finish
M401                                            ;Deploy probe
M557 X15:300 Y50:350 S57                                   ; define mesh grid
G30 P0 X15 Y345 Z-99999       ; probe near leadscrew one
G30 P1 X15 Y55 Z-99999      ; probe near leadscrew two
G30 P2 X300 Y205 Z-99999       ; probe near leadscrew thre
G30 P4 X160 Y205 Z-99999; probe the middle
G30 P5 X15 Y65 Z-99999          ; Corner
G30 P6 X15 Y350 Z-99999         ; Corner
G30 P7 X305 Y350 Z-99999        ; Corner
G30 P8 X305 Y65 z-99999 S3      ; Corner and calibrate 3 motors
M374                                            ; Save calibration data. Default is sys/heightmap.csv
G29                                                     ; Probe the bed and save height map to file
M402                                            ;Retract probe
M291 P"Probing mesh grid process finished !" R"Probing.." S1 T2
G1 X182 Y206 F5000

homeall.g

G91                     ; relative positioning
G1 Z5 F6000 H2          ; lift Z relative to current position
G1 H1 X-355 Y355 F6000  ; move quickly to X or Y endstop and stop there (first pass)
G1 H1 X-355             ; home X axis
G1 H1 Y355              ; home Y axis
G1 X5 Y-5 F6000         ; go back a few mm
G1 H1 X-355 F360        ; move slowly to X axis endstop once more (second pass)
G1 H1 Y355              ; then move slowly to Y axis endstop
G90                     ; absolute positioning
G1 X182 Y206.4 F6000    ; go to first bed probe point and home Z
G30                     ; home Z by probing the bed

[jay_s_uk]

Ok. You should only have 3 probe points defined in your bed file.

Everything has to be in the same order too.
So if you M584 Z axis are mapped front left, front right and back centre, the M671 and probe points in the bed file have to be in the same order.

Here are my config.g extracts and my bed file

;############## Leadscrew Location ###################

; Leadscrew locations (really, kinematic coupling locations) extracted from CAD model assuming back right build plate corner is (0, 0)
M671 X250:-250:0 Y270:270:-265 S20 								; Front Left: (484.5, 548.5) | Front Right: (-6, 548) | Back: (244.5, 17) M671 X234.5:-256:-5.5 Y274.5:274.5:-257 S20

bed.g

if !move.axes[0].homed || !move.axes[1].homed	; If the printer hasn't been homed, home it
	M98 P"0:/sys/homex.g"	; home y and x
;
M98 P"0:/sys/homez.g"			; home z
;
M561							; clear any bed transform
;M558 P9 H5 F120 T24000			; increase dive height
M98 P"bed_threeScrews.g"		; perform bed tramming
echo "Bed Traming Cycle: 1 - Difference was " ^ move.calibration.initial.deviation ^ "mm"
;
while move.calibration.initial.deviation >= 0.01		; perform additional tramming if previous deviation was over 0.01mm
  if iterations = 5
    abort "Too many auto tramming attempts"
  M98 P"bed_threeScrews.g"		; perform bed tramming
  echo "Bed Traming Cycle: " ^ iterations + 2 ^ " - Difference was " ^ move.calibration.initial.deviation ^ "mm"
  continue
;
G28 Z							; home z

bed_threescrews.g

G30 P0 X235 Y242.5 Z-99999         							; Probe near front left leadscrew
G30 P1 X-245 Y242.5 Z-99999        							; Probe near front right leadscrew
G30 P2 X-0 Y-250 Z-99999 S3     							; Probe near back leadscrew leadscrew and calibrate 3 motors

[MartinNYHC]

I'm running into 5 iterations every time. Just recognized that one of my leadscrews often gets stuck when moving the bed. Need to find out the reason for that.

Phew....my build seems to ba a never ending story.

[MartinNYHC]

OK, at least I fixed my Z leadscrew issue.

The first problem I have is, that at the first iteration of probing the bed near the left two leadscrews, the hotend is moving over the defined X/Y max limit and crashes into the end of the rails. Maybe I'm blind but cannot find the misconfiguration.

Here's my complete config:

config.g

; General preferences
G90                                                      ; send absolute coordinates...
M83                                                      ; ...but relative extruder moves
M550 P"duet3"                                            ; set printer name
M669 K1                                                  ; select CoreXY mode

; Drives                                                 ; X:0.0, Y:0.1, E:0.2, Z_left_rear:0.3, Z_left_front:0.4, Z_right:0.5
M569 P0.0 S0                                             ; physical drive 0.0 goes forwards
M569 P0.1 S0                                             ; physical drive 0.1 goes forwards
M569 P0.2 S0                                             ; physical drive 0.2 goes forwards
M569 P0.3 S0                                             ; physical drive 0.3 goes forwards
M569 P0.4 S1                                             ; physical drive 0.4 goes forwards
M569 P0.5 S1                                             ; physical drive 0.5 goes forwards

M584 X0.0 Y0.1 Z0.3:0.4:0.5 E0.2                         ; set drive mapping
M350 X16 Y16 Z16 E16 I1                                  ; configure microstepping with interpolation
M92 X200.00 Y200.00 Z400.00 E405.18                      ; set steps per mm
M566 X600.00 Y600.00 Z24.00 E120.00                      ; set maximum instantaneous speed changes (mm/min)
M203 X18000.00 Y18000.00 Z6000.00 E1200.00               ; set maximum speeds (mm/min)
M201 X3000.00 Y3000.00 Z100.00 E5000.00                  ; set accelerations (mm/s^2)
M906 X1600 Y1600 Z1600 E1600 I30                         ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                                  ; Set idle timeout

; Three axis setup - leadscrew positions
M671 X11:11:426 Y355:51:205 S20			                 ; Set up three Z-axis location

; Axis Limits
M208 X28 Y24 Z0 S1                                       ; set axis minima
M208 X355 Y355 Z400 S0                                   ; set axis maxima

; Endstops
M574 X1 S1 P"io3.in"                                     ; configure active-high endstop for low end on X via pin io3.in
M574 Y1 S1 P"io4.in"                                     ; configure active-high endstop for high end on Y via pin io4.in

; Z-Probe
M950 S0 C"io7.out"                                       ; create servo pin 0 for BLTouch
M558 P9 C"^io7.in" H20 F1000 T6000                       ; set Z probe type to bltouch and the dive height + speeds
G31 P500 X36.47 Y-4 Z1.72                                ; set Z probe trigger value, offset and trigger height
M557 X50:300 Y80:355 S50                                 ; define mesh grid

; Heaters
M308 S0 P"temp1" Y"thermistor" T95000 B3950              ; configure sensor 0 as thermistor on pin temp1
M950 H0 C"out2" T0                                       ; create bed heater output on out1 and map it to sensor 0
M307 H0 B0 S1.00                                         ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0                                                  ; map heated bed to heater 0
M143 H0 S120                                             ; set temperature limit for heater 0 to 120C
M308 S1 P"temp0" Y"thermistor" T500000 B4723 C1.19622e-7 ; configure sensor 1 as thermistor on pin temp0
M950 H1 C"out3" T1                                       ; create nozzle heater output on out2 and map it to sensor 1
M307 H1 B0 S1.00                                         ; disable bang-bang mode for heater  and set PWM limit

; Fans
M950 F0 C"out4" Q500                                     ; create fan 0 on pin out4 and set its frequency
M106 P0 S0 H-1                                           ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"out5" Q500                                     ; create fan 1 on pin out5 and set its frequency
M106 P1 S1 H-1                                           ; set fan 1 value. Thermostatic control is turned on
M950 F2 C"out6" Q500                                     ; create fan 2 on pin out6 and set its frequency
M106 P2 S0.3 H-1                                         ; set fan 2 value. Thermostatic control is turned off
M950 F3 C"out7" Q500                                     ; create fan 3 on pin out7 and set its frequency
M106 P3 S1 H-1                                           ; set fan 3 value. Thermostatic control is turned off

; Tools
M563 P0 S"Hotend" D0 H1 F0                               ; define tool 0
G10 P0 X13 Y20 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
M575 P1 S1 B115200                                       ; enable support for PanelDue
M501                                                     ; load saved parameters from non-volatile memory
T0                                                       ; select first tool

bed.g

if !move.axes[0].homed || !move.axes[1].homed	; If the printer hasn't been homed, home it
	M98 P"0:/sys/homeall.g"	; home y and x

M98 P"0:/sys/homez.g"			; home z

M561							; clear any bed transform

;M558 P9 H5 F120 T24000			; increase dive height

M98 P"bed_threeScrews.g"		; perform bed tramming

echo "Bed Traming Cycle: 1 - Difference was " ^ move.calibration.initial.deviation ^ "mm"

while move.calibration.initial.deviation >= 0.01		; perform additional tramming if previous deviation was over 0.01mm

  if iterations = 5

    abort "Too many auto tramming attempts"

  M98 P"bed_threeScrews.g"		; perform bed tramming

  echo "Bed Traming Cycle: " ^ iterations + 2 ^ " - Difference was " ^ move.calibration.initial.deviation ^ "mm"

  continue

G28 Z							; home z

bed_threeScrews.g

G30 P0 X41 Y355 Z-99999       		; probe near leadscrew one
G30 P1 X41 Y55 Z-99999      		; probe near leadscrew two
G30 P2 X338 Y205 Z-99999 S3      	; probe near leadscrew three

[jay_s_uk]

G30 takes into account the probe offset. So you need to take that into account.
If you're going to 355 for example, that will be offset a further 4mm to take your y-4 into account

[MartinNYHC]

Got it, thanks!

So now all three points will be probed:

9/18/2020, 11:00:53 AM 	Bed Traming Cycle: 1 - Difference was 0.004mm
9/18/2020, 11:00:53 AM 	Leadscrew adjustments made: 0.163 0.171 0.158, points used 3, (mean, deviation) before (0.164, 0.004) after (0.000, 0.000)

but when I do a G29 afterwards, the heightmap looks like

I'm wondering if I assembled the three bed holder at the right positions. Currently it looks like this:

Left Front:

Left rear:

BTW: this is not the final bed setup. Just reused some old parts to check if that all works out

[dc42]

You have an apparent twist in your height map. Typical causes of this:

1. If it's a CoreXY printer, check that the gentry is flat and not twisted. My E3D tool changer suffers from this if I don't put padding under one of the feet.
2. If the print carriage rotates about the X axis as it moves along it, this rotation will change the distance between the nozzle and the bed. If the X axis uses two parallel linear rods, check that there is no relative twist between them.
3. Or of course the bed could be twisted.

[MartinNYHC]

Gantry and bed are not twisted.

I just levelled the bed with a digital leveler and ran a G32. Although the bed should be in level it was set down on the right side, where the roll screw is located.

[MartinNYHC]

Found out, that I forgot to change the steps after changing the Z axes to SFU1204. At least it looks a little bit better now.

9/18/2020, 1:33:08 PM 	Bed Traming Cycle: 1 - Difference was 0.010mm
9/18/2020, 1:33:08 PM 	Leadscrew adjustments made: 0.068 0.043 0.066, points used 3, (mean, deviation) before (0.059, 0.010) after (-0.000, 0.000)

Any other ideas?

[engikeneer]

@MartinNYHC check how level your two guide rails are for the Y axis. Check both along their lengths individually and for any height difference between them.

From you height map, it looks like the three points you probed for the auto tramming are all at the same height, give or take. This means that it has correctly levelled the bed based on these three points. I'm assuming here that the 0,0 point is at the front left in the photo of your bed (where I'd expect it).

Looking at the heightmap, it seems that your y-rail on the right hand side (at your x-max side) is not flat compared to the left hand one, leading to the twist you are seeing in your height map.

[MartinNYHC]

@engikeneer Just measured and the front end of the right extrusion is 1mm higher. How the hell shall one assemble the frame that it is 100% square?

[whopping pochard]

@MartinNYHC build it on a surface plate. I’m actually lobbying for our maker space to get one so I can use it for my next build...

For my BLV I printed off two copies of the jigs and used those to hold both sides simultaneously. Still don’t have it up and running again though!

[engikeneer]

@MartinNYHC if you find an answer to that, please let me know! I don't have a digital level gauge so just kept adjusting mine, redoing the mesh, then repeating until I gave up

One other thought. You can probe more than three points if you like and anywhere on the bed. It will then do least squares to get the average bed plane and auto tram to that (thats why it gives a std dev before adjustments). Might be worth considering when you've done what you can with mechanicals to minimise the bed mesh?

[MartinNYHC]

@engikeneer Yes, I already added some additional probing points. Will try it out tomorrow.

[MartinNYHC]

Since I don't want to reassemble the frame once again before I'm sure what exactly the problem is, I just placed a washer between the bed frame and the bed holder on the right side. Looks better...