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Switching Extruders with TWO steppers

Posted by chromvis 
Switching Extruders with TWO steppers
April 23, 2017 08:59PM
Hi everyone,
I made dual extruder printer with swinging extruders each with its own stepper. Servo rotates 180 with its arm sliding through the hole of swing-lever. This allow alleviation for servo positional error.

My main problem is Marlin configuration. If you set #define SWITHCING_EXTRUDERS - system automatically assume that there is only one extruder stepper.
I found in Marlin_main.cpp assignment for 2 steppers (line 10044) but it did not help.
Switching extruders is very convenient since it automatically swing extruders and correct for calibrated offsets in all axis, but currently it block the second extruder stepper.

Any suggestions for workaround or software (firmware) correction?
Re: Switching Extruders with TWO steppers
April 23, 2017 10:55PM
In two files (Marlin_main.cpp line 10044 and stepper_indirection.h line 389) there is an analysis for SWITCHING_EXTRUDER definition. In both lines replace SWITCHING_EXTRUDER with any other nondefined identifier and everything works.
This is just workaround and not a proper solution.
Re: Switching Extruders with TWO steppers
April 24, 2017 03:25AM
Although Marlin believes there is only one stepper, you are able to send T0 / T1 toolchanges and the right stepper extrudes? At the right offset ?

If I got you right, you have a dual extruder setup, not switching extruder. You can make the slicer do the toolchange things, like servo angle and offset control.

Edited 1 time(s). Last edit at 04/24/2017 03:32AM by o_lampe.
Re: Switching Extruders with TWO steppers
April 24, 2017 01:41PM
Yes, it is dual extruder setup. But physical extruders are set at an angle and can swing for 12 degrees around horizontal axis (I attach picture). configuration.h file in marlin offer very convenient setup with SWITCHING EXTRUDER option where all offsets (X, Y, an Z) and activation of swinging servo is included. It dopes not exist for dual extruders. With simple dual extruders you have to manually align hotends at exact same height and when you print with one extruder, the second mess the print with its oosing. If there is separate standing towers not used extruder can kick them off. Swing has been done before, but people complain about servo accuracy. Setup, which I implement, is not affected by 5 - 10 degrees of servo inconsistency.
I actually found the way to activate second stepper when swing to second extruder, but I face motion problem. It seems that second extruder offset is not accounted. Will work on it today.
open | download - 2E-3DPrinter-s.jpg (397.3 KB)
Re: Switching Extruders with TWO steppers
July 15, 2018 02:18PM
Hi everybody, I'm new in this forum, but it's almost two years that I started building a 3d printer called "Stratos" by its designer. I called mine "Cosac Stratos" and applied little
modifications to the original project. A few months ago I upgraded adding a second extruder; both were fixed, moving only along the Z axis. It worked, but I was not satisfied
with that situation because of the interference between the work of the two extruders, so I made them swinging with a servo. I tried different configurations with Marlin, SWITCHING
EXTRUDER, SWITCHING NOZZLE, combinations of the two, but it seems that the servo prepare one extruder in the right position to print and in fact is the other stepper that
start pushing the filament. I read what has been written in this topic and found it very interesting, but I didn't understand what was ment by "nondefined identifier". Is there anybody
that has gone further and could help me? Thanks a lot.
Re: Switching Extruders with TWO steppers
September 08, 2018 02:30PM
Will this change work for me too. I am running 3 extruders 3 nozzles from a rumba board I need a way to tell servo 3 angles for so it switches with T0 T1 T3. It will switch 2 right now but limits me to only 2. I will be adding 2 more for 5 if I get this to work Thank you for any help have a great day
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