candolini
Posts: 4
Joined: Wed Mar 02, 2016 12:03 pm

Apply retraction to 2nd nozzle at startup on dual prints.

Thu Mar 03, 2016 10:40 am

Using a FF Creator Pro.

The standard startup script for a dual print wipes the nozzles, then moves right into printing, without applying a filament retraction to the inactive tool head - this leads to oozing of the inactive extruder. This (as far as I know) can't be cured with a skirt/brim as whichever tool head runs first, the other will ooze.

You can combat this by modifying the startup script and manually add a retraction - in my case, E-12.0 (S3D applies an E- 12.0 during normal tool changes which works perfectly once the cycle gets going). The problem is that this is unmanaged by S3D, so it doesn't know that once this extruder comes online in the process, it needs to apply the extra restart distance (in my case, E11.5).

I would suggest having the startup script apply the correct retract after the wipe using a tied variable - something like:

G1 E[filament_retract] F600

In a manner where S3D recognizes it needs to apply the restart distance after the tool change. I believe this would eliminate all oozing (at least in my experience).

Zorgonaute84
Posts: 58
Joined: Sun Feb 07, 2016 7:30 am

Re: Apply retraction to 2nd nozzle at startup on dual prints

Wed Mar 09, 2016 8:14 am

How man ! I've got the exact same issue !!!

If you find a solution please, share it here...

KC_703
Posts: 238
Joined: Tue Aug 26, 2014 5:23 pm

Re: Apply retraction to 2nd nozzle at startup on dual prints

Wed Mar 09, 2016 8:45 pm

You can try the "Extra Restart Distance". Not sure if it will work at the beginning of the print, but should work if you're using a skirt and ooze shield.

Note, a negative value will prime the hotend.

Could also increasing wipe or coast settings... again use with ooze shield to ensure proper priming on tool change.

candolini
Posts: 4
Joined: Wed Mar 02, 2016 12:03 pm

Re: Apply retraction to 2nd nozzle at startup on dual prints

Wed Mar 09, 2016 10:56 pm

With a lot of messing around I've got around the worst of it by modifying my startup script, as well as using a 2 pass brim and 1 pass ooze shield - for the most part i'm ooze free.
Here's how i'm configured:

In my startup script:
1. T0 nozzle purge and wipe.
2. T0 nozzle E-12 retract.
3. T1 nozzle purge and wipe.
4. T1 nozzle E-12 retract.
5. T1 nozzle E8 partial restart. (This means net E-4, but I found pulling the filament back farther and then restarting it a bit worked better than just doing a straight E-4).
6. T0 nozzle E10 partial restart (net E-2 on this nozzle).

In S3D:
1. 2 pass brim, both nozzles. If possible offset the brim the width of your nozzles (34mm for me), otherwise, just as wide as you can.
2. 1 pass ooze shield, both nozzles.

In cycle:
1. 2 pass brim starts with T0. It takes about 1/2 of the first pass on a medium size model to begin extruding - but not ooze in between. S3D now applies the E-12 and knows about it and will apply correct restart.
2. 2 pass brim starts with T1. Takes about the first entire pass before material flows, but no ooze. S3D now applies the E-12 and knows about it and will apply correct restart.
3. The rest of it is handled well by the ooze shield.

Since doing this, no issues. No need for prime pillar or anything like that - just the 2 pass brim and 1 layer ooze shield.

I've attached my startup script if it helps anyone - this is for a FlashForge Creator Pro, so others may need to adapt. The purge and wipe will occur at table front left.

Code: Select all

; **** Replicator 1 dual start.gcode ****
;preperations----------------------------------------
M73 P0 ; enable build progress
G162 X Y F3000 ; home XY maximum
G161 Z F1200 ; home Z minimum
G92 Z-5 ; set Z to -5
G1 Z0 ; move Z to 0
G161 Z F100 ; home Z slowly
M132 X Y Z A B ; recall home offsets
M135 T0 ; select right extruder
G1 Z5 F1200 ; retract Z
G1 X-128 Y-78 F6000 ; move to T0 prep position
G130 X20 Y20 Z20 A20 B20 ; lower stepper Vrefs while heating
M126 S[fan_speed_pwm]
M140 S[bed0_temperature] T0
M134 T0 ; stabilize bed temperature
M104 S[extruder0_temperature] T0
M104 S[extruder1_temperature] T1
M133 T0 ; stabilize right extruder temperature
M133 T1 ; stabilize left extruder temperature
G130 X127 Y127 Z40 A127 B127 ; default stepper Vrefs
G92 A0 B0 ; zero extruders
;reposition for T0-------------------------------------
G1 Z0.4 ; position nozzle
G1 X-128 Y-78 F6000 ; move to T0 prep position
;T0 prep and wipe------------------------------------
G1 X-110 E20 F300 ; purge T0 nozzle
G1 X-105 Z.15 E-12 F300 ; T0 retract and wipe
G1 X-100 Z.4 F600 ; T0 lift off
;reposition for T1-------------------------------------
M135 T1; select left extruder
G1 X-128 Y-72 F6000 ; move to T1 prep position
;T1 preperations--------------------------------------
G1 X-110 E20 F300 ; purge T1 nozzle
G1 X-105 Z.15 E-12 F300 ; T1 retract and wipe
G1 X-100 Z.4 F600 ; T1 lift off
;Prep extruders for print start----------------------
G1 X-128 Y-69 F6000 ; move to clear position
G1 E8 F300 ;partial restart T1
M135 T0; right tool
G1 E10 F300 ;partial restart T0
G92 A0 B0 ; zero extruders
M73 P1 ;@body (notify GPX body has started)
; **** end of start.gcode ****

Zorgonaute84
Posts: 58
Joined: Sun Feb 07, 2016 7:30 am

Re: Apply retraction to 2nd nozzle at startup on dual prints

Fri Mar 11, 2016 7:32 am

I found an acceptable solution (maybe the one that Simplify have to implement in their next release).

This is the interesting part of my startup script for dual extrusion process :

STARTUP SCRIPT :
G28 ; home all axes
T1 ;switch to the 2nd Extruder
G92 E0 ;zero the extruded length
G1 F200 E13 ;extrude 10mm of feed stock
G92 E0 ;zero the extruded length again
G1 E-15 F3000 ;retraction before toochange

T0
G92 E0 ;zero the extruded length
G1 F200 E13 ;extrude 10mm of feed stock
G92 E0 ;zero the extruded length again


Noticed that I performed a 9mm retraction on the T1 tool after reset to zero the extruder.

Then I genererated my Gcode as normal, but before to print it, I edited it.

I openend it with a TextEditor, and then find the first toolchanged (Ctrl + F : T1)
then I added this command just between the positionning and the reset to zero.

BEFORE:
G92 E0
G1 E-15.0000 F3000
; layer 2, Z = 0.2
T1
; prime pillar
G1 X81.968 Y160.384 F12000
G92 E0
G1 X90.568 Y160.384 E0.1078 F1442
G1 X90.568 Y168.984 E0.2157


AFTER:
G92 E0
G1 E-15.0000 F3000
; layer 2, Z = 0.2
T1
; prime pillar
G1 X81.968 Y160.384 F12000
G1 E0 F3000
G92 E0
G1 X90.568 Y160.384 E0.1078 F1442
G1 X90.568 Y168.984 E0.2157

The command I added is the same used for each toolchanging process for the rest of the print. I think Simplify 3D forget to add it at the first layer.

sreisig1
Posts: 30
Joined: Fri Sep 02, 2016 4:57 pm

Re: Apply retraction to 2nd nozzle at startup on dual prints

Sun Oct 02, 2016 6:51 pm

Any update on these? Thinking about giving one of them a go. Using a FFCP and trying to get better dual color prints. Issue I'm having now is when using both a prime pillar and ooze shield, it doesnt do the brim, so it gets right to printing and the idle nozzle oozes so when it starts printing it looks like its doing a ditto print. With the prime pillar off and brim on, I don;t have that problem because the ooze adds to the brim. Thinking about trying one of these scripts.

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