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3D printer rounded corners


extrusion - What causes these round corners

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Modified 1 year, 2 months ago

Viewed 48k times

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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.

  • extrusion

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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.

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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.

See this visual guide on more information

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.

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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.

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Enable "classic jerk" in the firmware and put it to 12 on both X and Y.

That helped me get perfect prints.

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Your printer is over extruding.

It looks like PLA on the photo, the preset multiplier in S3D is 0.90 (not 1.0!)

The nozzle diameter should be the same as the extrusion width (both 0.40).

When you set the width to auto you get a bigger width. I don't really know why, but it was told me so.

If you print 1.75 mm you have to measure it and (the actual diameter is often around 1. 78 mm, maybe less too). The multiplier of 0.9 is because PLA is softer then ABS for example. Maybe you should try other multipliers as well, maybe down to 0.85 in 0.01 steps.

I hope you can figure this problem out. I am experimenting by myself for days now to get it as sharp as possible. The goal is to get an edge with the diameter of the nozzle - not a bit more.

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marlin - What can I do to remove the rounded corners using Junction Deviation?

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Asked

Modified 1 year, 10 months ago

Viewed 16k times

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I recently upgraded my Creality Ender 5 with an SKR Mini E3 V2. 0 running Marlin 2.0.7.2. The printer has also been modified with an all-metal hotend and a direct drive conversion kit that uses the extruder stepper motor. In test prints of the XYZ calibration cube, I have found that the edges of the cube are rounded over. After some research, it appears this is due to either the acceleration/jerk settings or the junction deviation settings.

The issue now comes in that no matter what setting I change, the prints do not change. Currently in the Marlin firmware, I found that the Classic Jerk is disabled in Configuration.h line ~786. The default JUNCTION_DEVIATION_MM is 0.013. Since Classic Jerk is disabled, Junction Deviation shows up in the menu under Menu --> Configuration --> Advanced Settings. I printed 4 cubes for 4 different Junction Deviation settings: 0.013, 0.075, 0.130, 0.300. All cubes have the same characteristic over-corrected corner with no visible changes (Picture below)

My questions are:

  • Why aren't the prints being affected by changing the Junction Deviation setting via the menu? The Junction Deviation setting is stored in memory using Menu --> Configuration --> Store Settings and I have confirmed the values remain in memory after cycling the printer.
  • If Classic Jerk is disabled in Marlin firmware, would an M205 X[Jerk] Y[Jerk] Z[Jerk] command before a print enable Classic Jerk for that print?
  • What happens if an M205 command is sent that sets XYZ as well as J? (e.g. M205 X[Jerk] Y[Jerk] Z[Jerk] J[Dev]). Would it ignore Classic Jerk values if Classic Jerk is disabled in firmware?

I have read through the following posts already

  • Setting Junction Deviation in firmware has no effect
  • https://reprap.org/forum/read.php?1,739819
  • https://blog.kyneticcnc.com/2018/10/computing-junction-deviation-for-marlin.html
  • https://www.reddit.com/r/3Dprinting/comments/dx8bd/here_is_why_you_should_disable_junction_deviation/

My next steps:

  • Re-enable Classic Jerk in Marlin and see if the print behavior changes
  • Other?
  • marlin
  • creality-ender-5
  • skr-mini-e3

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Contrary to what's implied by its name, junction deviation does not produce rounded corners. It merely allows violations of the acceleration profile at corners that would be allowed if the corner were rounded by the deviation. So you should not expect changes to it to create or eliminate unwanted "rounded corners".

However I don't think what you're seeing are rounded corners. They're bulging corners, likely produced as a consequence of the toolhead moving slower just before and after the corner in order to honor the acceleration profile. My guess is that your acceleration limits in Marlin 2.0 (500 mm/s² if I recall correctly) are a lot lower than on the original Creality firmware.

You can and probably should increase the acceleration limits. The machine should handle 1000 mm/s² easily and up to 3000 mm/s² or even higher with some ringing; I use lower acceleration for the outer walls and let it run wild for inner walls and infill. But the real solution to your bulging corners problem is to enable and calibrate Linear Advance to get a consistent extrusion rate with varing speed. For my Ender 3, the right constant is around 0.5-0.6 s (yes the units are seconds - it's mm/(mm/s)) for PLA. You can use the calibration pattern generator to run the calibration yourself, but I would expect the same results.

This will significantly impact your print speed, since Marlin applies E-axis speed, acceleration, and jerk limits to the advance offsets. You can get a lot of it back though by increasing those limits though; the defaults are a whole lot lower than what the machine can handle. 200 mm/s speed limit and 10000-15000 mm/s² acceleration limit (vs 25 and 5000 defaults in Marlin, respectively) are within reason.

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When a junction deviation is set too low it will mess up every other thing you have been trying to do to perfect your extrusion.

It messes up

  • retraction,
  • linear advance,
  • s-curve,
  • the entire print.

I had been messing around with my jerk and acceleration values, my retraction values, and my linear advance values, and no matter what I did, nothing fixed the actual issues. I even gave up on Bowden and tomorrow a Hemera direct drive will be delivered.

Now I found this setting in my printer menu, changed the value from 0.017 to 0.2 and those bulging corners are now gone (in fact I had to up my linear advance a bit because it was actually rounding off the corners making them too thin).

The stringing is gone now as well (low jerk on retraction and you might as well not retract at all).

Seriously, unless you are using a CNC or CoreXY, I don't see why you would even use junction deviation.

As to why nothing is changing for you, this is because other settings are bad as well. So it's still slowing down too much in the corners while material is still oozing out.

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What can I do to remove rounded corners using connection deviation?

marlin reality-ender-5 skr-mini-e3

I recently updated my Creality Ender 5 with SKR Mini E3 V2.0 running Marlin 2.0.7.2. The printer has also been modified with an all-metal hotend and a direct drive conversion kit using an extruder stepper motor. In the test prints of the XYZ calibration cube, I found that the edges of the cube were rounded. After some research, it turned out that this is due to either the acceleration / jerk settings, or the transition deviation settings.

Now the problem is that no matter what setting I change, the prints don't change. Currently in Marlin firmware I found that the classic dash is disabled in config.line h ~786. The default value of JUNCTION_DEVIATION_MM is 0. 013. Because Classic Dash is disabled, Connection Rejection is displayed in the menu under Menu -> Configuration -> Advanced Settings. I printed 4 cubes for 4 different connection rejection settings: 0.013, 0.075, 0.130, 0.300. All cubes have the same characteristic overcorrected angle with no visible changes (picture below)

My questions are:

  • Why does changing the connection reject setting through the menu not affect the output? The connection rejection setting is stored in memory via Menu -> Configuration -> > Save Settings, and I have verified that the values ​​remain in memory after the printer is cycled on.
  • If Classic Dash is disabled in Marlin firmware, will the M205 X[Dash] Y[Dash] Z[Dash] command before printing enable Classic Dash for this print?
  • What happens if an M205 command is sent that sets XYZ the same as J? (e.g. M205 X[Jerk] Y[Jerk] Z[Jerk] J[Dev]). Will it ignore classic dash values ​​if Classic dash is disabled in the firmware?

I have already read the following posts

  • Setting connection rejection in firmware has no effect
  • https://reprap. org/forum/read.php?1,739819
  • https://blog.kyneticcnc.com/2018/10/computing-junction-deviation-for-marlin.html
  • https://www.reddit.com/r/3Dprinting/comments/dx8bd/here_is_why_you_should_disable_junction_deviation/

My next steps are:

  • Re-enable Classic Dash in Marlin and see if the typing behavior changes
  • Other?

@user3883001, 👍5