Ultimaker 3 Infill Causing Print Failures

[JMESZAROS 0]

We have been having trouble with our UM3 and printing TPU. We print a ton of large TPU parts (right up to the top of the build area in some cases) on our UM2+, and almost never have a failure. On the flip side, almost every TPU part we print on the UM3 fails.

What happens is the material gets curled up in the feeder as it is so flexible and causes under extrusion. I have adjusted the material drive tension and nozzle temperatures up and down to no effect thinking that this was the issue. I have used default Cura and printer settings, tweaked Cura and printer settings, used comparable settings to the UM2+ (that is working just fine), and yet the UM3 fails every time.

I have noticed that there is a major difference in how the UM3 prints the infill that I believe is gooping up the nozzle as it is putting down too much material.

You can see this by changing to layer view and changing the settings:

The UM2+ looks like this:

This looks quite good to me - no issues.

And this is what the UM3 looks like:

This looks like a problem waiting to happen:

1. It is printing an internal shell rather than just connecting to the existing shell

2. The next portion weaves back and forth and overlaps itself far too much. It also overlaps the 'infill shell'.

3. There is a third portion that is a 'bridge' to the infill.

4. Finally get to the infill, the part that I am expecting.

Here are our last 5 prints all lined up:

I believe this is why too much material is being put down. With no where to go, the part gets lumpy above the surface of the current layer, the extruder drags the nozzle back and forth through this, and eventually clogs the nozzle, causing the under extrusion that we get every time we print.

I have tried various different infill patterns, but they all have the above features to varying extents.

Any thoughts on what we need to change? We are printing 24/7 with our UM2+, and barely touch our brand new UM3.

Edited June 1, 2017 by Guest

[JMESZAROS 0]

I went through and reset all my Cura settings to defaults, and now it seems to look the way I would expect:

I'm really not sure what setting was driving this issue, but after resetting to defaults, and using the recommended settings, then switching over to custom and setting my infill line distance to get the correct density, it looks like it should work.

I would have kept the recommended settings, but the infill settings don't seem to be working properly - 20%, 50% and 100% all look the same. All good - I am trying a test print now, and will see how it goes.

Edited June 2, 2017 by Guest

[JMESZAROS 0]

Started getting under extrusion about 5 layers in and had to stop the print.

Any one else had any luck printing TPU on a UM3?

[kmanstudios 1,120]

I have had luck with Ninja Semi-Flex. Would that count?

[tomnagel 126]

This is definiteky not a known problem. Are you using a recent version of Cura? Your print profilies could be faulty, consider a reinstall action of Cura. And then manually remove the folder with the profiles (which one, @ahouben?)

And after so many failed prints, could your nozzle be clogged? Try cleaning it using the cold pull method (aka atomic method) https://ultimaker.com/en/resources/23132-clogged-print-core

[JMESZAROS 0]

I'll have to check my notification settings as I did not see your replies

I am running Cura 2.6 (beta). I uninstalled, and removed all of the 'Cura 2.x' folders leftover in C:/Programs. I then reinstalled, opened my part, set the infill to 20% using the recommended settings without changing anything else, and it does not look anywhere close to 20%:

I am thinking there is definitely an issue here - even the gradual settings has some very obvious overlapping:

Switching over to custom, the infill is 96% by default, while being very dense at the bottom, is very sparse at the top:

Which leads me to try and tweak these settings to avoid this:

Any thoughts as to why this infill is being so difficult?

[JMESZAROS 0]

Just to follow up - this is easily fixable, if you know what to change.

It seems the newest version of Cura has a new setting called 'Gradual Infill Steps' that reduces the infill density the farther away from the top or bottom of the part you get. It must also increase it closer to the top and bottom from what I have been experiencing. The UM2+ defaults to a value of 0, and UM3 defaults to a value of 4.

Set gradual infill steps to 0 if you are experiencing similar issues. It seems to render any other infill settings almost useless.

Hopefully this can help someone out!

Jeff

[tomnagel 126]

Or press "20% infill" in recommended mode (in Cura 2.6, the gradual infill mode has been promoted to the infill settings in recommended mode)

[JMESZAROS 0]

Hmm, yes it looks like that works - must've been after my reinstall. Before I reinstalled, I do not believe the recommended settings were turning off the gradual infill steps setting for the different infill percentages (it was not working properly).