Dual Extrusion Adventures Continue
Well, this isn’t Part IV, but I could have called it “A New Hope”. Unfortunately, this entry ends with “The Extruder Stikes Back.”
My primary goal for dual extrusion is to use HIPS as dissolvable support structures with ABS. Cleaning off support material and finishing prints is time consuming, so it’s a great option.
From my last post, I had a few things I wanted to try:
Change to dual ABS extrusion for the offset calibration. I think the HIPS shrinks at a different rate and oozes a bit more than the ABS. Once dialed in, I’ll switch back.
I haven’t done that yet, but think it’s pretty darn close. Though I do see a slight offset in the wipe/prime tower, so I’ll do another tweak.
Try using Ooze Shield and/or a wipe and prime tower (thanks to Ben & Ray at LulzBot for the suggestion.
The wipe/prime tower is a must-do (it really helps with even flow). Ooze shield is still on the to-try list.
Change the z-hop value in Cura. I’m getting extruder strikes during travel, and suspect that’s why my offset keeps changing.
I discovered that the nozzle on the secondary extruder wasn’t fully screwed in – that was causing the head strikes.
Level – and I mean really level the bed. I have the impression that there’s enough sag with the dual extruder on the x-axis that I need to level in the center, but it’s just as possible that the bed isn’t really perfectly level – need to nail this one down.
There’s definitely sag with the dual extruder in the center of the x-axis, but by leveling well I can dial it in so everything still works. I’ll write up a post on my leveling method – it seems to work pretty well for a dual-extruder setup.
Add white marks to the dial on the front of the dual-extruder. This is used to set the vertical offset between the two extruders – the marks will help me see if it’s actually moving during printing.
Haven’t done this, but it doesn’t seem to be as big an issue as I thought.
At some point I need to add cooling fans to the extruders so I can work with PLA – I hear that there’s other folks working on that, so I’m waiting to see what they come up with.
I’m trying out a prototype – more info here.
Now back to the update. My first attempt to print something that requires extensive support was using a model of a starship from thingiverse. It’s been a bit of a challenge. Initially I had adhesion problems between the HIPS support base structure and the ABS object. A chat with Brent at Lulzbot, and a couple of suggested tweaks, gave me what appeared to be a great print.
So off to the limonene bath with it. First thing I learned, is that even with dissolvable support, it’s worth using a Dremel tool to cut away the bulk of the support material – this one took two days to dissolve. When it was done, the nacelles and weapons pod broke away as I lifted it out of the bucket – clearly some layer adhesion issues. Then when I turned it over, I discovered that it too had the dual-material adhesion problem. Still working on this one – any ideas or suggestions would be welcome.
While it was dissolving, I started to print a minion chess set from thingiverse as a gift for my wife. I didn’t check the support Cura was generating closely enough, and ended up with a failed first print.
For some reason it’s not automatically generating support for the arms. Fiddling with the settings got it working, if I set it to an overhang of 0.
So the next print worked better, but I forgot to do a wipe tower – not sure if that’s why the arms are still wiggly at the bottom, or if it’s more of the same problem as with the starship. I’m trying another print now, and including an ooze shield with it to see if that helps at all.
So, that’s the update. I think I may try using Simplify3D or Slic3r to see if it’s a slicing/gcode problem, otherwise it’s more fiddling with settings in my Cura profile.
Comments/suggestions/shared misery all welcome as usual!