one cube corner always messup

I just bought the lulzbot 4 recently. I am having trouble printing a small cube (20 x 20 x 10 mm) using HIPS. the problem is at the top right corner of the cube (when looking from top-view on to the print bed) is always a mess. The printing pattern is that it always lift the z at the lower left corner then move to the top right corner to start extrude new layer. And small mess looked like a sticky ball will start build up at the top right corner but the other corners are fine.

I thought the problem is that it extrude too much after it retract, so I increase the retract value from default of 2 to 3.5mm but it is still a mess. please help
20mm-box.gcode (75.1 KB)
my fast_HIPS_no-support_pt35nzl_pt22layer.ini (3.28 KB)

Would you mind taking a picture of that corner? That will help to show the severity of the Z lift seam.

Alternatively, you can also randomize that, by selecting in Slic3r: Print Settings > Layers and perimeters > Advanced > Randomize starting points (You may have to switch Slic3r into Expert mode, by going to File > Preferences > Mode).

I would set the retraction setting back to it’s previous value as well.

I have tried to random the corner but that mess up all of the corners instead of just one. I also tried to reduce retract to 1mm but it didn’t help. I am using the filament from Lulzbot so that should not be the cause.

The picture quality is not that good since I only got a phone’s camera at the moment. Please let me know if you want to see better pictures, so I will borrow a DLSR from my brother tomorrow.

edit: forget to tell that all those pics are taking from the same cube but different view. There is only 1 mess up corner there.

got to sleep first, it is 1:20 AM. here

Would you mind reprinting the object with this profile, and positng an image of the resulting print showing the corner in question? Try the print without making any modifications to the Slic3r configuration, so we can minimize the amount of variables.

I just use the profile provided with much better result. But that corner still has trace of problem as it is more coarse than other corners. By coarse I mean the layers are bigger and more noticeable than the rest. And also the sharpness of that corner is more round.

It is quite difficult to capture even using a DSLR due to its size and color but it is visible by eyes. The other corners look very fine and sharp.

In Slic3r, try changing the following setting:
Filament Settings > Filament > Filament > Extrusion Multiplier and change the value from 1 to 0.98

Reslice the model and see how that changes the way the Z lift looks on that corner.

If you’d like to try a new experimental version of Slic3r, version 1.1.3 found here: has a new feature, Seam Position which configures the logic for choosing the start point of perimeters. This may help the quality of that corner.

I have tried to reduced the extrusion multiplier to 0.98 but it seems worse. The other corners become more coarse so I tried increase it to 1.02 but that 1 corner still shows problem. By the way, I have been using Slic3r 1.1.3 all along.

In order for the printer/slicer to have crisp clean corners and unnoticable layer height changes, you need several things balanced and spot on. The extruder will have a slightly different extruder steps per unit between different filament types, as the hobbed bolt will grab onto the material a little bit differently. Usually the difference is negligible and not something to consider. The perimeter speeds and retraction settings need to be balanced as well. You may want to start by slowing your perimeter speeds a bit. You may also want to turn on this setting: Slic3r > Printer Settings > Extruder 1 > Retraction > Retract on layer change

How should I balance the perimeter speed and retraction setting? Faster perimeter speed need faster and longer retraction? The retraction speed I am using is 25mm (default 30mm) I want to increase it but not sure what is the maximum the motor can handle, do you think the motor can handle 30mm or more? Also the Retract on layer change is already enabled by default.

would you mind sharing your Slic3r setting for fast printing 0.27 layer height? It would be nice if I can compare the setting to get general idea of what I should expect. I am not sure if I am running too fast or not.

my goal is to print something as big as human head so I need to have fast printing speed with accuracy. I have bought ABS, PLA, and HIPS from lulzbot and I think HIPS should be easy for starter. I am not sure what material is suite for the requirement. Do you think I am using the right material?

For now, leave the retraction settings alone. For what you’re wanting to do with larger models, the Z axis lift you see on the perimeter won’t be as noticiable. We currently only have the Medium HIPS config as a recommended starting point. If you’d like, adjust the layer height by changing the value in Slic3r, at Print Settings > Layers and perimeters > Layer height. After a test print or two, adjust the speed how you’d like, you’ll notice when you are trying to print to fast for your current settings.

For printing large objects, HIPS will work well, as will PLA. ABS will have a greater tendency to warp/split at that scale (you can still use it, but you’d need to use an enclosure to minimize such things). ABS works well, some of the large parts on the TAZ were printed with ABS, such as the Z axis motor mount, but for ease of use, at that scale, use HIPS or PLA.