# What causes these round corners

Nozzle diameter = .4
Extrusion multiplier = 1
Extrusion Width = .45    <-- I feel like this could be reduced to fix it?

Layer Height = .3


I'm using Simplify3D.

• What looks interesting is that the right hand side bevel seems to have excess material, but the left hand side does not. I assume this is the part which you're asking about? Extrusion width should match the nozzle size. – Sean Houlihane Jan 2 '17 at 1:09
• Left side does as well. Look at each corner, you see how it looks like there is a circle on each of them? Also, I'm using the extrusion width profile from the manufacturer...presumably it's supposed to be good? – easycheese Jan 2 '17 at 1:30
• Is that photo from the top or bottom of the print? – Gunslinger Jan 2 '17 at 7:41
• The effect can be seen on every layer. – easycheese Jan 2 '17 at 13:15
• To me, it appears that the short segment is offset about 1mm in the NE direction. Left side seems slightly open, right side seems compressed. So on the left side, the curve is due to the sides peeling back from open ends, at the right, there is over-extrusion. This would make it a mechanical problem of some sort - possibly due to drag from the filament feed making the travel asymetric. – Sean Houlihane Jan 2 '17 at 13:19

If it's on each corner, and not the layer change corner, it's a combination of overshoot and the short "pause" of the printer when it changes direction.

You can minimize it, but it won't go away 100% (due to overshoot from direction changes), usually models with a slight rounded corners work great. If you, say, increase the jerk as an experiment and they get sharper (but you obviously have to deal with potential ringing artifacts) then it's due to that pause and acceleration after a direction change.

I would try lowering the temperature a bit to slow the flow/oozing of the nozzle and calibrate extrusion - just to keep the settings tight as possible to keep dimensional accuracy, but not under extrude obviously.

If it's where a layer change occurs, tweak and play with retraction settings - such as coasting and extra distance on restart (you can put negative values here). Once those are set, as an advanced tweak, try to max the z speed... Obviously this involves motor current, testing for skipped steps etc... but this would make the layer change a bit quicker, to further reduce oozing, due to the delay in layer changes if retraction settings don't fix it.

Usually, you can fix the corners with retraction settings but then it can mess up other parts of a model, since those settings are global... I wish slicers were more intelligent.

• I don't think it's whiplash. It it was it would be less uniform and not on every axis. Also while there is no photo they did not complain about the walls having deformities caused by the random offset. – StarWind0 Jan 2 '17 at 22:45
• true, other case would be if the belts were loose on both. forgot about that. – Eric Kelly Jan 3 '17 at 17:17
• One of the belts was loose, I also played with the retraction settings and speeds. Problem has definitely minimized. – easycheese Apr 20 '17 at 1:31

Oh thats simple. First you will see the "elephants foot" on first layers if you have the extruder over-extruding or do not have enough distance between the bed and nozzle.

It's very common that the first couple of layers of a print is wider than you expected them to be. This is because you will generally want to make sure the first layer is nicely squished into the build platform so that it sticks properly. By doing this the plastic gets squished out into a thicker line than normal and thus the bottom of the print will bulge out a bit like an elephant's foot. You can decrease this effect by leveling your bed so that the nozzle is slightly further away from the bed and lowering the bed temperature a bit. It's hard to get rid of this effect entirely without sacrificing bottom layer quality and bed adhesion. It will be easier on small prints as they are less likely to warp and detach from the platform and you can therefore get away with not squishing the first layer as hard.

If you are seeing this on all layers. That means you have oozing. When your printer hits the end of the line. It has to slow down, stop and start the next vector. During this time if your printing very hot, you will ooze material at this intersection. Also the extra time over that spot mayhaps also warm the corner, causing more disruption. Best thing in this situation is to verify you cannot lower temps more. Add a fan. Also double check that you are extruding the exact amount you think you are. (distance of material and the material size average)

Here is another visual trouble shooting guide

I will note, I don't think thats too bad. If it needs to fit into something, just clip it.

• Hmmm, I guess it could be oozing due to the temp. I'll try some cooling settings. – easycheese Jan 2 '17 at 13:17
• If you want to post your firmware settings and temps as well. – StarWind0 Jan 2 '17 at 22:46

Three factors that will impact the 'sharpness' of corners, first is your extruder speed, second is retraction rate and third is nozzle diameter.

By slowing down your extruder will be able to track the features of your model better. I generally try to print with extruder speeds of ~10mm/s which gives fairly good results. The nozzle diameter will be the most extreme limiting condition on how sharp you can get your corners. This I think is likely your issue.

Retraction rate could have an effect on the corner sharpness. I don't think that's the problem you're experiencing but worth mentioning. Depending on the specific geometry if your nozzle stops at a corner while it raises in Z if your retraction is too low additional filament can ooze out making the corners appear more rounded.

Typically a nozzle diameters are about 0.4mm which is pretty sharp, however if you have something larger that could effect it as well. Again, not your specific issue but something to keep in mind for future builds.