One nozzle works fine, other one oozes a bit, screwing up dual extrusion prints

[soofle616]

FF Creator pro running sailfish 7.7 with programs generated by makerware 2.4.1.24 and run off the SD card. I've only done 2 dual extrusion prints so far and unless I can figure this out probably won't do any more. My right extruder (currently loaded with white abs) works fine when it prints on its own. My left extruder (red abs) also works fine on its own. When hot, both leak a little material though the left does so much more than the right. This has never been a problem until I try to print with both heads in the same job. Even with the makerware barrier walls in place, and capturing strands of plastic, the left head oozes enough that I end up with little blobs of red plastic all over my print. This creates two problems, one, my prints suck because the white plastic is "stained" with red and two, the little blobs occaisionally stick to the nozzle and drag through the print making an absolute mess of things. I don't believe it to be a nozzle height issue because I can print with either side alone with no issues of dragging, it's only when I try to print with both sides on one job. Is there something I should be looking at in terms of the extruder itself? A profile change to increase retract of material on that side? Like most of the other issues I've had with this machine so far (thankfully not very many) the problem seems to be more prevalent during the early layers of each build. As I get into higher and higher layers the barrier wall does it's job and I don't have any more blobs in the print.

temps, 230/230/110 (left/right/bed)
speeds, 70/90
infill 20%
layer height doesn't seem to matter but I mostly print at .2mm
2 shells
no raft or supports when possible.

[curious aardvark]

drop the left temp down to 220 or 225.

The wird thing is that white abs prints lower than other abs and white pla (the stuff I've got anyway) prints alot higher than other pla.

Just finished a test print and my pla only starts to print well at 220plus. Hel it won't even extrude at 195 - my standard pla print temp. (it sticks to a cold bed and doesn't warp or shrink so I'm assuming the pla sticker on it is correct)

But I do remember my white abs printing lower than the other colours.

[Geoff]

drop the left temp down to 220 or 225.

The wird thing is that white abs prints lower than other abs and white pla (the stuff I've got anyway) prints alot higher than other pla.

Just finished a test print and my pla only starts to print well at 220plus. Hel it won't even extrude at 195 - my standard pla print temp. (it sticks to a cold bed and doesn't warp or shrink so I'm assuming the pla sticker on it is correct)

But I do remember my white abs printing lower than the other colours.

I think you need to start checking the types of plastic you have, sounds like it might be the root of your ABS issues and why you could never print with it properly, you have been printing in ABS and PLA and don't know which is which lol. Just smell it, thats the dead giveaway - PLA has such a distinctive smell you can't miss it.

@Soofle6161
This is a pretty common problem, and even on sailfish v1.0 and an old flashforge, the same thing happens.
The problem is, unless the plastic is identical, it will have a slightly different melting point, so you basically need to find the baseline for how low you can actually extrude it. Dropping it a few degrees as he said above won't really help unless you know what you are aiming for.

Start low, and see the lowest heat you can extrude at, do that for both nozzles and it will be slightly different for all your plastics. It did take me some time before I got clean dual colour but I got there eventually.

Printed in ABS and ABS.. on a caveman wooden FF creator...
ddcc.JPG

Now, if it were another machine, I would say go and increase the retract settings, I think the stock retract on a FF is about 4mm@30ms..

Now, not sure in the current sailfish, but I would be changing that to about 6mm@50ms retract, suck it back up faster and enough that when its ready to print there isn't too much required to feed back through.

[curious aardvark]

I think you need to start checking the types of plastic you have, sounds like it might be the root of your ABS issues and why you could never print with it properly, you have been printing in ABS and PLA and don't know which is which lol. Just smell it, thats the dead giveaway - PLA has such a distinctive smell you can't miss it.

lmao - nah I know what the plastic is. Only real issues I had with abs is the warpage and the fact that it prints 1% smaller than the model and doesn't like sticking to things much - got plenty nice prints - just on a raft. Pla doesn't do any of that stuff - so is just more 'set it and bugger off ' friendly.
But this white pla is tricky stuff. Prints fairly nicely at 220 - not a patch on the other three rolls of pla which print at 195-200 and nowhere near as clean as the white abs. Still getting stringiness at 220 - probably going to work down 1 degree at a time to find the optimal temp. It's fine for big prints - and I've got a bunch of biggish stuff to print for christmas presents, so it'll get used.

I'm leaning towards the additive that gives plastic it's white colour being a hi-temp material in it's own right. As both my white abs and pla filament print at more or less the same temp.

As far as dual extrusion goes - yeah that's currently fighting back lol

I do now have two nozzles the same size - so can calibrate with both nozzles installed - although one is now 0.5m nozzle size.
And that seems to be causing problems with s3d - ah well, such is life :-)

I should be getting some 0.4mm nozzles soon.