Nylon grinding issues Ultimaker3+

[ecu3dprinting 0]

We have been attempting to print a flu virus using 3D Universe's nylon filament and using PVA as support material. After about 8-12 hours of printing (of a 36 hour print) we have issues with the nylon filament grinding causing a failed print. We were able to print the same model successfully in 3D Universe's PETG with the PVA support. We have attempted multiple times and tried adjusting the tension on the back of the Ultimaker3+ but keep resulting in the same issue. We also have to clear the print core with hot/cold pulls after each attempt with nylon. It is unclear if the grinding is causing the clogged nozzle, or a clogged nozzle is causing the grinding.

 

We sliced the model in Cura 3.4.1, and did not make any modification to the recommended settings for nylon. The .gcode and pictures are attached for your viewing pleasure. We haven't been able to locate any discussion of this issue with nylon on the forums yet. Any ideas on how to tweak the settings would be greatly appreciated!

 

Thank you for your help!

 

ECU 3D Print Studio

UM3E_Laupus_Flu.gcode

[geert_2 556]

I have never printed with nylon, so I am guessing here. Nylon is *very* susceptible to moisture absorption. In injection moulding it is known that in only a few hours, it can absorb so much moisture from the air that production is impossible. So the material has to be dried well, and kept dry during the whole process.

 

Could this also be the problem in your setup?

 

For printing nylon, you would first need to dry the spool in a temperature controlled oven. And then store it in a fully closed box with rotating spool holder, also *while printing*. With only a little opening for the filament to exit. Also, put a big bag of desiccant in that box.

 

There have been talks about several proposed models in this forum, some time ago. Maybe you could find them back? Big food boxes could be a good starting point. Or dedicated machines (I don't remember their names).

 

But as said, this is guessing.

 

[ultiarjan 1,220]

In my experience different types of nylon vary a lot in the amount of moisture they absorb. The ultimaker brand nylon prints pretty easy imho. I never dried it but I keep it in a box with descendants. Even during printing. I've also used samples of other brands and found some to be very difficult. It also matters where in the world you live... I'm not in a very humid place so that also helps ofc..

 

When you material gets to wet you can usually hear it when printing. 

[ecu3dprinting 0]

I knew there was something I forgot to mention...I don't believe moisture is the issue. We keep the nylon stored in vapor barrier bags with desiccant. When extruded, the nylon doesn't show any of the tell tale signs of moisture, e.g., bubbles, popping noise, wisps of smoke/water vapor, etc. While we are located in the muggy North Carolina, we are in an academic library whose HVAC/climate control is outstanding due to the nature of our collections.

 

In this case, I'm more inclined to think that the filament itself sucks, or we need to do a better job of adjusting the filament profile.

[gr5 2,002]

Don't mess with the feeder.  It's almost always a problem at the other end (the print head) that causes the grinding.

 

Two possibilities:

1) Maybe you have too many retractions.  I'm thinking this virus might have many "islands" on a given layer?  If true there may be so many retractions that it's grinding up the filament for that reason.  I like to keep this down to 10 retractions for any spot of filament. To do that set maximum retraction count to 10 and set minimum extrusion distance to your retraction distance (probably 4.5mm - just use 4.5mm if you don't know what it is).

 

2) Maybe you just have too much pressure in the head.  Try printing at half speed.  Yes it will take almost twice as long but better than a failed print and you will learn something (whether it's grinding because there's too much pressure in the print head).  You can just do this change in the TUNE menu on the printer.  Or in cura.