What caused this layer failure

Discussing what we do with our prints after we make them (clean up, integration, etc)

What caused this layer failure

Postby bbrown64 » 2015-Jul-Wed-08-Jul

Image It is weird because part of the print is OK and part is not.
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What caused this layer failure

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Re: What caused this layer failure

Postby Mooselake » 2015-Jul-Wed-11-Jul

It looks like overextrusion and possibly too high a print temperature.

Read up on extruder calibration. Yes, it's a slic3r doc but it also applies to Cura or whatever. It links to Triffid Hunter's guide, which is getting pretty dated, but there's some good tips in there. Just don't change your X, Y, or Z calibration from the calculated values (in the olden days pulleys were printed and inconsistent, today they're cnc'd aluminum), and ignore anything about recompiling marlin since it's all done with eeprom settings these days.

For a quick test reprint something that's prone to blobbing and use the Repetier-Host sliders (I assume Cura's pronterface emulation includes something similar) to reduce the extruder temp and flow rate while printing.

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Re: What caused this layer failure

Postby bbrown64 » 2015-Jul-Wed-15-Jul

It is weird that problem only occurs if a print something round, with a smallish diameter. If you look at the photo, part of the print is OK. That is why I would not think it is over extrusion or temp problem. I print with PLA it is set at 210/ 60 for my temps.
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Re: What caused this layer failure

Postby Mooselake » 2015-Jul-Wed-16-Jul

What happens if you print two of them at the same time? Are you using a fan, and at it's max speed?

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Re: What caused this layer failure

Postby frankv » 2015-Jul-Wed-16-Jul

It appears that the part that's OK is where it is vertical or inward sloping, whereas where it's outward sloping (i.e. you have a slight overhang at each layer) you have the problem. Why that would cause this problem is beyond me, but maybe this observation will trigger an idea for someone more knowledgeable than me.

FWIW, when I told Cura a minimum time per layer, it seemed to ignore that setting. So small objects would get overheated and soft and distort. As per Kirk's suggestion, try printing two of these objects some distance apart to see if that helps.

If I was you, I'd try reducing your nozzle temperature a bit... I print PLA at 190.
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Re: What caused this layer failure

Postby Mooselake » 2015-Jul-Wed-16-Jul

Higher temps will make the plastic more, well, plastic. Think drippy and runny.

Print temp is a trade off. Higher temperatures will produce better layer bonding (which will be more of an issue with ABS), but at the same time will cause the extrusion to sag before it cools.

Printing two copies will cause the head to move between objects, allowing them to cool before the next layer is printed, which is why it's a common suggestion. In this case i'd still lean towards too high a print temp since even the bigger areas look pretty rough. Being off on the extruder calibration will make it worse since the extra plastic will push off to the outside.

Frank, besides a minimum layer time there's probably a minimum print speed setting (there is in slic3r, at least), and the minimum speed wins in a conflict. Kisslicer will print a cooling tower beside the object to give more time, but Cura and Slic3r don't take that approach. I wonder if adding layer switch code to retract, move off to the side, then unretract (or whatever it's called), move back, and start printing the next layer would work. It might just end up with a drip that knocks the print over - maybe somebody should try it for grins. I would, but still need to fix my motor off Z drift.

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Re: What caused this layer failure

Postby Bob-StPaul » 2015-Jul-Thu-17-Jul

In Slic3r you can add your own simple shape as a cooling shape before you slice.
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Re: What caused this layer failure

Postby JonS » 2015-Jul-Fri-01-Jul

You might be experiencing a very small, and intermittent, size leak from that nearby TARDIS. Have you tried moving it further away?
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Re: What caused this layer failure

Postby Mooselake » 2015-Jul-Fri-09-Jul

It might be better to put the printer inside the Tardis and save all that desk space. Could be a nice place to fit that 4x8' CNC machine you always wanted but never had the room for.

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Re: What caused this layer failure

Postby bbrown64 » 2015-Jul-Sat-10-Jul

I did move the Tardis about 4' away from the printer. It did help. I also slowed down the print for infill, outer shell, and layers. Then everything worked out like it was suppose to. ;)
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Re: What caused this layer failure

Postby bbrown64 » 2015-Jul-Sat-10-Jul

I could never get a 4x8 cnc machine in my apartment. I would have to rent a climate control storage locker with power to do that. :)
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Re: What caused this layer failure

Postby Mooselake » 2015-Jul-Sat-13-Jul

bbrown64 wrote:I could never get a 4x8 cnc machine in my apartment. I would have to rent a climate control storage locker with power to do that. :)

No, no, no. You put the 4x8 router inside the tardis... bigger on the inside.

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Re: What caused this layer failure

Postby Jamie_K » 2015-Jul-Sat-20-Jul

Every slicer I've tried I've found to be very stupid sometimes. I hate them all. It would not surprise me if the slicer is trying to be clever in handling overhangs, which is generating this artifact.

In Slic3r, convex overhangs sometimes printed at a different (faster) speed, regardless of any setting I could find. Slicers are also generally ignorant of the fact that the E dimension is often a bit sluggish to respond compared to X/Y/Z.
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