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Spiral print rough on one side

Posted: Fri Apr 13, 2018 5:05 pm
by jon_bondy
I've printed this object before, and it printed fine. And the section that is rough is vertical, so the shape should not be a problem. One side (the side away from the main door) is rough and has tear out, while the rest of the print is pristine. I am now using the BondTech extruder, but have no reason to suspect that to be an issue. This is Taulman T-Glase, while the original was PolyCarbonate, but I can't see how that would make this kind of a defect.

Any thoughts?

Re: Spiral print rough on one side

Posted: Fri Apr 13, 2018 5:43 pm
by Vice Chief
I had a symptom like this in some large prints. The problem turned out to be that the "rough" side was not getting enough air from the cooling fan(s). Try to visualize that side of the print. Does the fan dwell on that area as much as it does the other areas?

Re: Spiral print rough on one side

Posted: Fri Apr 13, 2018 6:52 pm
by detroitus
I sometimes get exactly the same issue when I'm trying to print overhangs on the side of the nozzle opposite where the cooling fan is. Seems to be an issue with the way the dual extruder part cooling is set up. You might try looking into some of the redesigned cooling ducts that people have put up on Thingverse or even try applying some external cooling during the print.

Re: Spiral print rough on one side

Posted: Sat Apr 14, 2018 12:36 am
by Julia Truchsess
T-Glase and PC are going to have very different melting, extrusion, and solidifying characteristics, that could absolutely account for this kind of different outcome.

Re: Spiral print rough on one side

Posted: Sat Apr 14, 2018 10:58 am
by jon_bondy
@detroitus, @vice chief:

The hot end cooling fans are in operation, but I blocked the cooling vents at the bottom of the hot ends, because neither T-Glase nor PC like being cooled. In addition, since the defects are on the back side of the print, they are neither closer to nor farther away from one of the fans: they would be equidistant at the moment when they were printed.

I have repeated the print with PC, and it went fine. And despite the fact that they are different materials, the resulting prints look identical (and this is a visual sculpture, so that is the only thing I care about). So, I can avoid the problem by sticking to PC. Still, I wonder why it happened.

Re: Spiral print rough on one side

Posted: Sat Apr 14, 2018 11:06 am
by jon_bondy
@Julia Truchsess: I agree. The two prints were sliced with different templates, of course. The high quality of the front of the print and the tear outs on the back of the print remain mysterious. If the temperature and feed rate settings were wrong, I would have expected the front of the print to also be problematic.