I have a Rostock Max V2, and I've added a second extruder going into a y-splitter into a single nozzle on my printer. I have both extruders working correctly, but I'm having trouble tuning the retraction settings to prevent stringing when I switch between extruders during a print. My system is essentially identical to the setup seen here. However, I can't get my printer to retract as cleanly as the one in the video
What I'm trying to avoid is the long, thin "tail" that forms when retracting the filament from the hot end. That "tail" binds the other filament during the switch and makes the extruder grind a hollow spot on the filament.
I've had limited success tuning my retraction settings, but I find that I need different settings for different extrusion speeds. For example, after an extrusion like
G1 E20 F240 a 3mm retraction, 3mm extrusion, then a fast retraction creates a nice, clean break (this routine is recommended here by kraeger on the SeeMeCNC forums). However, after an extrusion like
G1 E20 F900 I have to use longer retractions to get a clean break. I think this might have to do with the filament acting like a spring inside the bowden tube. It would make sense to me that the harder you push the filament, the more you need to pull back to compensate for the pent-up spring force.
Here's my question: Is there a way to read the value of the extrusion speed, essentially the "F" term from the gcode commands, and change my retraction routine accordingly.
If F value < 500 Then do short retraction If F value > 500 AND F value < 1000 Then do medium retraction If F value > 1000 Then do long retraction
I'm using the tool change script feature in Simplify3D to store the tool change code.