Certain Angled Shapes have Rough Edge

[Wisar]

I am having trouble with certain angled shapes having one or two rough edges. The layer height is 0.1mm and as you can see from the coin the objects are pretty small. It is just certain angled shapes that seem to cause the printer some issues. The columns are all nice as is the very base of the pyramid. Even the loop at the top is good. Just one corner of each of the columns going up at an angle has a rough edge (inside of the right column in the picture)!



I have been adjusting all the ooze parameters 1 or 2mm retraction, wipe or no wipe, coast or no coast. Have also swapped around the "inside out" or "outside in" option to no marked impact. I am just not completely sure what I should be trying to adjust! The printer is a Makerbot Clone, the Wanhao Duplicator 4S. Print speed is set to 2800mm/min but slower speeds also seem not to matter.

Thanks for any pointers,
Will

[DarthRevan]

Do you see these same results with larger prints? Say this same print at 200% scale?

[Wisar]

Not as pronounced but the backside of the leg is very much rougher than the front side.

[dsegel]

That looks to me like positional accuracy problems with the printer. Try slicing your model with Slic3r or Cura and see if you have the same problems.

[Wisar]

The slicing rendering in Simplify3D looks ok but I guess that would be expected if the problem is the translation between slicer and firmware. I use Slic3r on my Prusa I3 and never tuned it for the Wanhao nor have I used ReplicatorG but I guess that is now something that I should probably do!

Cheers,
Will

[JoeJ]

That looks like cooling issues to me. And that's to be expected since you printing such a tiny part! If the layers are too small and can't cool, then they won't be as accurate as usual.

Try printing a larger piece. Maybe the same pyramid at 3x scale. Or print 3 pyramids at once! If that works better, that would be good confirmation that this is your issue.

[Wisar]

I am printing ABS at fairly slow speed and at just a tad above the lowest at which I can extrude which is about 210c (225c for first layer and then dropping from there layer by layer) and the heated bed at 110c for the first several layers and then dropping to 90c for the duration. I also have an uber-cool [http://www.thingiverse.com/thing:537918] ducted fan mounted for active cooling:

All that said, and to leave no stone unturned, I did print the three objects in the below picture in the same session. The problem with the Pyramid is still evident. The Surface calibration object is pretty good and the Marvin would be great except for the issue with the ring at the top and the extra brow above the left eye.

I am going to try and get ReplicatorG or Slic3r to work but in the meantime any other advice would be appreciated. It still seems to me like an ooze problem but I have tweaked parameters left right and center without fixing the issue!

Regards,
Will

[JoeJ]

If you have really good cooling already, then this could also be related to the overhangs. If you have a 45 degree angle like that, the larger the layer height gets, the more that each successive layer will need to "step over" from the one below it. If you draw out the layers on paper, this might make more sense. So reducing the layer height will help lower this "step over" size, which will likely make the overhangs look much better. 0.1mm is already fairly low, but maybe try 0.05mm just to see if it comes out any better.

[braddo]

Is that particular overhang on the same side as the longer portion of your heat block? I saw a similar thing and pulled my hair out over it until I noticed I only had the issue on one side of the print bed. I added some insulation to the underside of the heat block and cured it! Could be a contributor in your case, although the ragged edges did seem somewhat in a repeating pattern.