New i3V owner: A few beginner questions

But what you see from the bottom of the knob isn't directly supporting the top layers. The knob design fills in the layers at about 10mm high, and then adds low density infill for a ways before adding on the top layers. It still could be that the upper structure doesn't recover from the bridging issue - I'm just pointing out that there's more to the knob structure than you're thinking.

Was the extruder height recalibrated when you went from printing on glass to printing on tape? How do your two knob heights compare? I noticed that with the three knobs I printed previously, the one sliced in 0.9.9 came out about 0.3mm shorter.

I'm not sure what magic pixie dust did the trick, but the knob I just printed in new MakerFarm black PLA, with print cooling fan, cold bed with painters tape, 10mm/Sec retraction and sliced in Cura is at an entirely different level of quality than any of the three test prints I did before.

If you're interested (and who wouldn't be?) here are videos of the above prints.

First on glass, with a 70C bed, no fan:
https://www.youtube.com/watch?v=EiBWKgIjo1s

And on cold painter's tape, with a print cooling fan:
https://www.youtube.com/watch?v=lULGRCpxjqs

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Originally Posted by printbus

But what you see from the bottom of the knob isn't directly supporting the top layers. The knob design fills in the layers at about 10mm high, and then adds low density infill for a ways before adding on the top layers. It still could be that the upper structure doesn't recover from the bridging issue - I'm just pointing out that there's more to the knob structure than you're thinking.

Was the extruder height recalibrated when you went from printing on glass to printing on tape? How do your two knob heights compare? I'm curious whether the cooling fan makes a difference on the height result. FWIW, I noticed on my earlier diagnostic prints of the knob that the Slic3r 0.9.9 knob came out about 0.3mm short. The two I did with v1.1.6 were OK.

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Yes, you're right. There is additional structure, but even if the honeycomb ends up at the correct height, I've seen the mesh sink into the holes in the honeycomb with uncooled PLA. ABS seems to be a little more forgiving, but still benefits from a cooling fan.

Both knobs measure 15.01mm with calipers. I'm slicing with Slic3r 1.1.1. I'm using auto bed leveling, so it calibrates the Z axis for every print.

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Originally Posted by clough42

Then I re-ran the print on cold painter's tape, with a cooling fan, and the holes in the mesh are gone

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This is really interesting. I will try to play with heat bed temperature to see, if my results change. I do feel that the problem with blobbing I have is related to retraction, but need to play with parameters more, to understand, what helps in my case.

Quote:

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Originally Posted by printbus

I'm not sure what magic pixie dust did the trick, but the knob I just printed in new MakerFarm black PLA, with print cooling fan, cold bed with painters tape, 10mm/Sec retraction and sliced in Cura is at an entirely different level of quality than any of the three test prints I did before.

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I've printed small robot (http://www.thingiverse.com/thing:40212) with 0.1 layer height using Cura and Slic3r to compare. I haven't made photos yet, but results are really interesting. Will post later, but definitely shows that there are some things to improve in Slic3r settings, most probably related to retraction.