First layer issues

[LowLander]

Hi all,

I'm in the final stage of tuning a newly built Hypercube Evolution. I exclusively print PETG. I use an E3D Hemera (direct) and a genuine BLtouch v3.1.

Over the past few days, I've followed the steps detailed in https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation more times than I care to remember. Regardless, the filament either just wraps around the nozzle or drags through the first layer.

At this point, I've run out of ideas so any help would be greatly appreciated. (I've read most if not all related previous posts on this subject.) I'm running RRF3.

My config.g:

0:/sys/config.g
; Configuration file for Duet WiFi (firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v2.1.4 on Sun Jan 05 2020 16:21:30 GMT+0100 (Midden-Europese standaardtijd)

; General preferences
G21 ; set units to mm
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"oranjedraeck" ; set printer name

M667 S1 ; select CoreXY mode

M552 S1 ; enable network
M586 P0 S1 ; enable HTTP
M586 P1 S0 ; Network
; disable FTP
M586 P2 S0 ; disable Telnet

; Drives
M569 P0 S1 ; physical drive 0 goes forwards
M569 P1 S1 ; physical drive 1 goes forwards
M569 P2 S0 ; physical drive 2 goes forwards
M569 P3 S0 ; physical drive 3 goes forwards
M584 X0 Y1 Z2 E3 ; set drive mapping
M350 X16 Y16 Z16 I1 ; configure microstepping with interpolation
M350 E16 I0 ; configure microstepping without interpolation
M92 X80.00 Y80.00 Z400.00 E428 ; set steps per mm
M566 X900.00 Y900.00 Z12.00 E120.00 ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E420 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00 ; set accelerations (mm/s^2)
M906 X1500 Y1500 Z1500 E1000 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 S1 ; set axis minima
M208 X300 Y300 Z300 S0 ; set axis maxima

; Endstops
M574 X1 S0 P"xstop" ; configure active-low endstop for low end on X via pin xstop
M574 Y1 S0 P"ystop" ; configure active-low endstop for low end on Y via pin ystop
M574 Z1 S0 P"zstop" ; configure active-low endstop for low end on Z via pin zstop

; Z-Probe
M950 S0 C"exp.heater3" ; create servo/gpio 0 on heater 3 pin on expansion connector
M558 P9 C"^zprobe.in" H10 F120 T6000 ; set Z probe type to switch and the dive height + speeds
;M280 P0 S10 ; send control signal to BLTouch through servo/gpio 0

G31 P500 X20 Y-35 Z1.69 ; set Z probe trigger value, offset and trigger height

M557 X25:295 Y25:260 P5 ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
M143 H0 S120 ; set temperature limit for heater 0 to 120C
M307 H0 B0 S1.00 ; disable bang-bang mode for the nozzle heater and set PWM limit
M308 S1 P"e0temp" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M143 H1 S280 ; set temperature limit for heater 1 to 280C
M307 H1 B0 S1.00 ; disable bang-bang mode for the nozzle heater and set PWM limit
M305 H1 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 1
M301 H1 P16.9 I1.214 D57 ; PID settings for heater 1

; Fans
M950 F0 C"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1 ; set fan 0 value. Thermostatic control is turned off
;M106 P0 S0.3 H-1 ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency
M106 P1 S1 H1 T45 ; set fan 1 value. Thermostatic control is turned on

; 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

; Custom settings are not defined

; Miscellaneous
M501
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss

[jens55]

The issues you are reporting are pretty common with the causes generally being nozzle height and temperatures and bed surface.
Have you printed with petg before? What nozzle temperature are you using? What bed temperature ? Have you verified nozzle height (ie paper test with some dragging) ?
Sorry about asking such basic details but I think it is best to sort the basics before worrying about the finer details of config.g

[Veti]

@LowLander said in First layer issues:

M308 S1 P"e0temp" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin e0temp
M305 H1 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 1

not sure if thats a problem but it cant hurt to clean this up.

RRF3 should only use M308

[LowLander]

Yes, I've been printing PETG for 4+ years on an I3 clone. Filament temperature is at 235C, bed at 50C. I print on glass with hairspray. These temps work on my I3, but with my 1st layer challenge I haven't been able yet to print a temp tower on this machine.

I'm well aware this is a common issue. I've been at this for days, so I decided to reach out for fresh perspectives. The BLtouch is new to me, but I expected that carefully following the steps in the guide would lead to at least a decent 1st layer.

[Veti]

try changing the temperature. one temperature on a printer does not translate well to temperatures on other printers. there can easily be a difference of 10 degrees.

i take it the first layer is not sticking well?

[jens55]

Yes, I would most certainly increase the bed temperature substantially. Try 75 or even higher. Best to increase in steps of no more than 10 degrees at a time so you don't end up with the print permanently bonded to the glass plate.

Have you verified that your gap between nozzle and bed is right (thickness of one sheet of paper) ?
Again, its important to sort out the basics first. Just because you installed a BLTouch doesn't mean the gap will be magically correct. It took me considerable tweaking before I got consistent results with the BLTouch.

[LowLander]

When I use the trusted method with a sheet of paper, the gap is too large for sure. I've incrementally changed the temps to 245 and 65 respectively, no observable difference.

If I determine Z=0 by having the nozzle touch the bed, I do get a line of extruded filament but it's not sticking to the bed and not squished at all. Something seems off with the Z offsets I obtain, but I can't figure out what or why (yet).

[tekkydave]

If you haven't already done so try adjusting the nozzle height whilst the first layer is printing using the 'Z Babystepping' controls on the DWC Status page. If you can find a height that works then adjust the G31 Z value in your config.g by that amount.
HTH

[droftarts]

@LowLander said in First layer issues:

M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
M308 S1 P"e0temp" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin e0temp

These are the default thermistor settings, for a Honeywell 135-104QAD-J01 thermistor that shipped with hot ends from RepRapPro, who have been out of business for 4 years! So I doubt you have the correct thermistor settings, and likely the temperature your heaters are reporting is not accurate. All 100k ohm thermistors have a resistance of 100k ohms at 25C, and will be fairly accurate at room temperature, but they report very differently as they get hotter. So please check what thermistors you have, and set them correctly, then you have a chance of accurately setting extrusion temperature.

Ian

[LowLander]

@tekkydave Thx! That did the trick. I needed to add .45 to my offset.

@droftarts Good catch. I've corrected it (again).