Dual Head Future upgrade ?...

[tachyio 0]

But I do notice the Bowden Tube "lag" as well. When the extruder gear reverses, the hot plastic continues to drip out.

This is fixable. This is an Dual head Ultimaker print:

http://www.thingiverse.com/derivative:27402

But you do not want to know how long the slicing took, as it was manually edited GCode to get it to work. (Not my print)

In Cura there's the retraction distance, under advanced options, though I haven't yet messed with it.

Should I try it out by setting a retract distance? I imagine that if the gear reversed enough...it could lift the filament back into the nozzle, maybe the retraction distance at this point in time is too short.

I visited a reprap farm yesterday and the guy said that if you retract the filament early enough, it shouldn't drip out over empty space...but that the GCode would have to do this before it reaching the empty space, since there is a retraction lag.

[joergen 2]

In Cura there's the retraction distance, under advanced options, though I haven't yet messed with it. Should I try it out by setting a retract distance? I imagine that if the gear reversed enough...it could lift the filament back into the nozzle, maybe the retraction distance at this point in time is too short. I visited a reprap farm yesterday and the guy said that if you retract the filament early enough, it shouldn't drip out over empty space...but that the GCode would have to do this before it reaching the empty space, since there is a retraction lag.

until cura has a working dwindle option, the retraction speed should be as fast as anyhow possible (i have set it to 50mm/s, which is pretty unachievable, but works). retraction distance depends on a couple of factors: length of your bowden, type of filament, temp in the hotend etc). I found 3mm good enough for my setup (long bowden), but 2mm might be sufficient for shorter setups. the retraction needs to overcome the curve of the bowden, and the springiness of the tube, in order to have any effect. too little, and you still get strings, too much, and you waste time, and risk to get a blob from too much push-on on the landing spot (plus the dreaded plug from dragging PLA up the brass tube). I would suggest to find first the lowest print temp you can get away with at your settings, and if you still get strings, increase the retraction distance by 0.5mm until they are gone...

[Daid 306]

Quick note, before I go to bed, I tried 10mm retraction for dual extrusion, still caused oozing. So dwindle is the way to go.