MakerGear Forum

Hi all,

First time poster here, but long time 3D printer enthusiast. I currently work at a school that has 3 Makergear M2's. I noticed that on my printed models there would be little blips (See attached), from what I believe to be layer changes. I've used a wide array of other 3D printers and slicing software but have never run into this problem. I don't really know where to go from here, but here is what I have tried (not in any particular order).

1. Enabled retraction between layers in S3D. This didn't help
2. Inserting G-code as a script between layers for retraction. I did this with retraction enabled and disabled. When retraction was enabled on top of my script it caused my model to have gaps in it (Can provide picture). The script alone didn't help.
3. Disabled 'Only retract when crossing open spaces' option. Still no improvement.
4. Tried using a different slicer program with same settings. Switched over to Cura which I use for my printers (Prusa i3, Wilson, and Mendel 90) at home. No noticeable difference in the defect I'm trying to sort out.

Also, here is some info about my setup:
Slicer: Simplify3D or Cura
Printer: MakerGear M2
Hotend: V3B

Anyways, I appreciate any suggestions on how to fix this problem. I am very satisfied with the M2 besides this little annoyance. I am sure it's probably just some little setting that I'm missing.

Can you tell if the nubs are at the "start" of extrusion of the "next" layer or at the "end" of extrusion of the "previous" layer?

For the latter case, look at using the "Coast" setting in S3D. Adding 1.0 mm of coast will cause the extruder motor to stop pushing filament 1 mm before the end of the last line of filament, which provides an opportunity to relieve any built up pressure behind the nozzle. (Basically, when the extruder motor pushes filament, it puts some pressure behind the nozzle, and when the extruder motor stops pushing, filament keeps coming out for a bit based on that pressure...) This can help prevent leaving a nub at the end of a line of filament by not drooling out filament just as retraction starts at the "end" of the "previous" layer.

For the former case, look at putting in a small NEGATIVE value in the restart distance. Say this number is -0.1 mm and the retraction is 1.0 mm (to pick some numbers, not to recommend them!). Then before a rapid move, the filament will be retracted 1.0 mm, but will only be returned 0.9 mm after the rapid is complete. This may help prevent putting a nub at the beginning of a new line of filament by not burping out filament on the return from retraction, which occurs at the "beginning" of the "next" layer.

Hope this helps!
Dale

Here is a fairly long thread on zits: http://www.forum.simplify3d.com/viewtopic.php?t=779

You can try all those suggestions, which includes Dale's suggestion of coast and restart distance settings. Some other things mentioned in that thread:
Drying your filament.
Using KISSSlicer, which supposedly has better seam hiding.
Turning down perimeter speed.
Using Simplify3D's setting where you specify where to start each layer (no need to turn off random infill any more).
etc. etc.

The last one not a fix per se, but I do find it is more aesthetically pleasing to have a single seam on one side of the print than zits semi randomly scattered all over. As Rob points out, injected molded parts all have a seam and nobody seems to care much.