by TLHarrell » Tue Nov 26, 2013 6:51 pm
Oozing is like what happens with a regular hot glue gun. The material in the nozzle leaks out when not being extruded. It should be solved by retract, but not always the case.
Two things affect the amount of "compression" in a Bowden tube. One you have discovered is the overall length of the tube. The other is the difference in ID of the tube to OD of the filament. A larger difference crates a bigger gap, and there's more space for it to pile up before it can be forced forward. This causes a delay when you command the extruder to push filament. This is like "backlash" in a CNC machine. There are settings to take care of that.
If you've mounted the extruder directly to the top of the bot, do you have it on a swivel mount? If not, your tube will bend more as you move up in Z height and cause a lot more force to be required to push the filament.
Displacement of a print at higher speeds may be a sign of dropped steps. If you command a move that it cannot do, due to acceleration, weight, etc, the motors will skip steps. This also happens if you hit a mechanical limit. Solutions are to reduce speed until you don't drop steps anymore, raise current on the drivers, and/or verify no binding on the axis.
I haven't seen a dual Bowden extruder setup before.
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