Bulges where perimeters start/stop

Hello all,

I've got a really odd artifact on my prints at the moment.

I'm printing a 20x20mm cube and the edges seem to bulge where the perimeter starts and stops on the corner.

images: [imgur.com]

I'm using Simplify3D and altered pretty much every setting under the sun!

I'm all out of ideas, so maybe someone has some advice on this troublesome topic?

Look forward to hearing any suggestions.

Regards,

Alex

Is this happening on all 4 corners or just 1..?

Try printing two of them at a time. The nozzle keeps coming back to the same, still hot plastic and dumping on more hot plastic. It needs a few seconds to cool. Maybe some over extrusion, too.

PLA? cooling fan? Have you completely calibrated the extruder?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks for the replies.

I've calibrated my extruder and flow rate with a single-walled calibration cube.

I don't think the hot plastic thing would cause this as I've got a minimum layer time on a 20x20mm of 15seconds with a blower fan on 100%.

It's happening on all 4 corners as I slicer alternates the starting corner every 4 layers.

I've spent a day of testing and got no further towards solving this.

EDIT:

When the perimeter starts, it seems to blob at the end, which causes further perimeter lines to bulge out.

I've tried coasting and less restart length to reduce this to no luck.

What I can tell is that the hot-end is stationary which causes the blobs at the start.

My acceleration is at 3000mm/s^2 and 20mm/s jerk.

Not sure if Simplify can get rid of this stationary moment in time?

Did you measure the wall thickness of that single-walled calibration cube...? If it is thicker than the diameter of your nozzle you should tweek the extrusion multiplier.

The thickness was within 0.01mm of the slicer settings, so I'm happy with that.

If it occurs only during 'Spiral vase modus' than it is a slicer problem.(one perimeter print)
I had just the same problem during printing with my bigger nozzles, 1.2 and 1.5mm. Only the effect was way bigger with mine part.
During regular printing this 'problem' does not occur at all.
See the last movie about that bulging in my 'Volcano' thread, you'll recognise it.

I'm having similar problems.
I'm experimenting with a series of 10mm cubes (https://www.thingiverse.com/thing:1240361)
I've tried various temperature and retraction settings with little success. I've been printing with seams aligned, so I'm seeing the problem mainly on one corner, where the print starts on a new layer after a travel move. I've been trying the "Extra length on restart" set to a negative number but anything more than -.5mm doesn't seem to make any difference. (This actually results in the sequence:

G1 E-2.00000 F2400.00000 ; retract
G92 E0 ; reset extrusion distance
G1 X40.843 Y68.776 F9000.000 ; move
G1 E1.50000 F2400.00000 ; unretract

so the filament doesn't actually feed and then retract, but only feeds the difference between the two parameters.)

Currently my settings are
.4mm nozzle
195 degrees
2mm retract
-.5mm extra length on restart
extrusion multiplier .98 (accurate when measuring 100mm of filament, but having gaps between fill and perimeter)
Using MakerBot colored PLA

Does anyone have suggestions for other things I might try?

Walt

Edited 1 time(s). Last edit at 03/11/2018 07:06PM by walts.

Do not test with 10mm cubes, It's very bad test, it's way to small, it's no reference to what your printer can do.
Test with larger parts say 50x50mm cubes first or even larger.
Smaller parts like these 10x0mm cubes need somewhat other settings.