Push-Pull Extruder Setup

gtj0

@NitroFreak said in Push-Pull Extruder Setup:

I think that´s pretty overkill, the easiest solution is to use 4mm ID PTFE tube for, like the 3mm filaments.
That will already reduce friction by alot.

That's what I do as well. With 4mm ID I don't have any issues.

dc42

@CTRDevelopments, I suggest you drive both extruders, but use a lower current for the earlier one in case the steps/mm don't quite match.

percar

I am using such a setup and have been using this for a number of year
At the current time I am using 2 bondtech QR extruders running them in series (not individual drivers)
This setup is working great I never have any issues with the filament skipping. One note I did experiment with using 2 drivers and using mixing ratio in the config.gcode in setup. This worked but the filament usage and time estimates were way off so I went back to just wiring the steppers in series

CTRDevelopments

Sorry for being slow in reply, I am printing up some parts to try to reduce the friction in the spool system and mount the second bowden extruder. Will report back once I have experimented

CTRDevelopments

Trying to setup the single tool. The extruder are connected to drives 3 & 4

M569 P3 S1 ; Drive 3 goes forwards, E0
M569 P4 S0 ; Drive 4 goes backwards, E1

M584 X0 Y5:6 Z7:8:9 E3:4 ; New drive mapping
M92 X320 Y320 Z1600 E880:417 ; Set steps per mm
M563 P0 D0 H1 ; Define tool 0
M567 P0 E1:1

But it doesnt seem to drive the second motor. Should the M563 have a definition M563 P0 D0:1 H1?

CTRDevelopments

Got it sorted, working really nicely now with the push-pull system, thanks for help Now all I need is a load filament macro to stop on motor skip

dc42

@CTRDevelopments said in Push-Pull Extruder Setup:

Now all I need is a load filament macro to stop on motor skip

You can do that, using stall detection. Just setup the stall parameters (M915), reduce extruder motor current (M913), and do a G1 H1 Exxx move.

CTRDevelopments

@dc42 said in Push-Pull Extruder Setup:

You can do that, using stall detection. Just setup the stall parameters (M915), reduce extruder motor current (M913), and do a G1 H1 Exxx move

DC, as I have two motors would it stop if either stalled?

M915 H200 E S10 R0 F0 ; set X and Y to sensitivity 4, do nothing when stall, unfiltered
M913 E30:30
G4 P100 ; wait 100ms
G91 ; use relative positioning
G1 H1 E3000 F3600

G90 ; back to absolute positioning
M400 ; make sure everything has stopped before we reset the motor currents
G4 P100 ; wait 400ms
M913 E100 ; motor currents back to 100%
G1 E50 F300 ; Purge

dc42

Yes it should stop when either stalls.

CTRDevelopments

Hi, having thought the push-pull was working nicely, and being out of filament for the past 6 weeks I have just got back to a mess on the bed. It looks like the initial extruder pushing up the bowden has exceeded the 'actual' extruder at the hotend. Its really strange though as I watched it on and off for 2 hours and it was perfect, they were matched exactly. Then this morning its not happy Are there moves in the slicer that could somehow negate the 'pushing' extruder?