Stringing problem with BMG direct drive and PLA
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Ok. Here is my config.g:
; Configuration file for Duet WiFi (firmware version 3) ; executed by the firmware on start-up ; ; generated by RepRapFirmware Configuration Tool v3.1.4 on Thu Jul 23 2020 19:42:11 GMT-0600 (Mountain Daylight Time) ; General preferences G90 ; send absolute coordinates... M83 ; ...but relative extruder moves M550 P"Ultibot" ; set printer name M669 K1 ; select CoreXY mode ; Network M552 P192.168.0.10 S1 ; enable network and set IP address M553 P255.255.255.0 ; set netmask M554 P192.168.0.10 ; set gateway M586 P0 S1 ; enable HTTP M586 P1 S0 ; 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 backwards M569 P3 S0 ; physical drive 3 goes backwards M569 P4 S0 ; physical drive 4 goes backwards M584 X0 Y1 Z2:4 E3 ; set drive mapping M350 X16 Y16 Z16 E16:16 I1 ; configure microstepping with interpolation M671 X0:350 Y0:0 S3 ; leadscrews at left (connected to Z) and right (connected to E1) of X axis M92 X88.89 Y88.89 Z800.00 E428.43:420.00 ; set steps per mm ; Movement settings M566 X800 Y800 Z300.00 E1000.00 ; set maximum instantaneous speed changes (mm/min) M203 X48000.00 Y48000.00 Z3000.00 E72000.00 ; set maximum speeds (mm/min) M201 X6000.00 Y6000.00 Z400.00 E10000.00 ; set accelerations (mm/s^2) M906 X1600 Y1600 Z800 E800 I30 ; set motor currents (mA) and motor idle factor in per cent M84 S30 ; Set idle timeout ; Axis Limits M208 X-23 Y-20 Z-1 S1 ; set axis minima M208 X330 Y340 Z430 S0 ; set axis maxima ; Endstops M574 X1 S1 P"xstop" ; configure active-high endstop for low end on X via pin xstop M574 Y2 S1 P"ystop" ; configure active-high endstop for high end on Y via pin ystop M574 Z2 S1 P"zstop+e1stop" ; configure active-high endstops for high end on Z via pins zstop and e1stop ; Z-Probe M558 P1 C"!zprobe.in" R0.2 A4 H3 F1000 T12000 ; set Z probe type to analog peizo and the dive height + speeds G31 P550 X0 Y0 Z-0.14 ; set Z probe trigger value, offset and trigger height M557 X10:300 Y10:300 S20 ; define mesh grid ; Heaters M308 S0 P"bedtemp" Y"thermistor" T100000 B4092 ; 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 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"e0temp" Y"thermistor" T100000 B4725 C7.06e-8 ; 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 M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit ; Fans M950 F0 C"fan2" Q100 ; create fan 0 on pin fan0 and set its frequency M106 P0 C"Layer Fan" S0 H-1 ; set fan 0 name and value. Thermostatic control is turned off M950 F1 C"fan1" Q100 ; create fan 1 on pin fan1 and set its frequency M106 P1 C"Tool Cooling Fan" S255 H1 T45 ; set fan 1 name and value. Thermostatic control is turned on ;M950 F2 C"fan2" Q25000 ; create fan 2 on pin fan2 and set its frequency ;M106 P2 C"LEDs" S0 H-1 B0 L0 ; set fan 2 name and 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 ; Custom settings M207 S1.5 F8000 ; set default firmware retract settings M912 P0 S-5.2 ; adjust MCU temp sensor ; Miscellaneous M501 ; load saved parameters from non-volatile memory T0 ; select first tool -
It really doesn't seem like this is retraction related, as the stringing is worse at 0mm, but only gets slightly better from all values up to 10mm.
Also, I should mention, I have PA tuned and on.
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are you 100% sure that you have a semitec thermistor?
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Now that you mention it, no. I bought a trianglelab v6 hotend, and upgraded the nozzle and heatbreak to genuine e3d parts. They say it is a semitec thermistor, but who knows.
I did try varying the temps from 180c to 225c, and the stringing is worse at lower temps... Now that I'm typing this, it occurred to me that I could still be too low. I'll try switching it to the generic thermistor settings.
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According to my cheap multimeter thermocouple, the temperature difference is about 30c, if it is to be trusted.
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Well I tried a print at 240c, so if the temperature really was off, it would fix it. Unfortunately, no luck. Still the same as 215c.
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and you tried different filament brands?
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On my BLV printer with a Bondtech BMG and E3D V6 direct drive with their catrtidge thermistor I print my pla at 220, retraction is 1.4mm @ 35mm/s speed, 200mm/s travel speeds and print speeds anywhere from 70-90mm/s. I get pretty much no stringing using prusaslicer with those settings. I have printed Esun, Sunlu and hatchbox PLA filaments. Of course many other types of filaments but for PLA, that is what I use.
I also use pressure advance set at .06.
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I'm starting to think it might be related to cooling. Watching closely, it doesn't necessarily start to generate a string at a retraction, but only when the nozzle leaves the part during a travel move.
This was printed at 215c, and towards the top I turned retraction to 0 to see what would happen.
A different print:
Also, here's a picture of my extruder carriage:
And no, I don't have any other brands of filament to try other than Hatchbox black PLA right now.
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This is a 12v milwaukee drill stand i printed yesterday with Hatchbox blue pla with the settings I mentioned above.
And this is my custom designed quick swap extruder setup I have on both of my BLV cubes. I know my wiring isn't neat by any means but it works perfectly
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Interesting. I use nearly the exact same settings as you do, but the main difference I think is the part cooling. You have a single fan blowing from one side, and I have two fans blowing from both sides at an angle. I think what may be happening is that there is turbulence where the two airstreams converge on my duct, and this causes the heat to build up. I might try redesigning my cooling duct so that the two airstreams are more aligned.
Also, I really like your quick change toolhead. Very compact.
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My fan blows on 3 sides actually. I designed the duct based on the original and it has an opening on the back and on both sides. I need to re-design it to flow more air though as the openings are very small. I'll see if I can get a picture.
EDIT: It was easier to just do a screenshot from fusion360.
