TPU FILAMENT PROBLEM WITH EXTRUDER

[Billucas]

Hi everyone. I bought some TPU filament (flexible). I tried 10 times to load the filament with no success. The gear skip at the end of loading. Many times I had to unscrew the front lexan plate, the pulley, to take off the filament which has roll around the gear ( Left extruder). A bit of plastic comes out of the nozzle.

Brand new N2 Plus received last week.
TPU good quality
Filament roll around the gear after loading and unloading.
Tried nozzle temperature between 215-250.
No plastic comes out when printing process.
ABS and PLA print before with success.
I used nozzle cleaning rod.

Do you have a idea for me please? I still have 4 roll of TPU left!!
Thank you!
Luc

[dhylands]

My brother had a similar issue with his N1. I suggested that he do a cold pull (he was previously using ABS) to clear all of the old plastic out of the nozzle/extruder. That seemed to help.

To do a cold pull, unload your filament and then remove the acrylic cover. Manually push the filament into the hot-end, bypassing the gear. Push through old filament until you see it coming out of the nozzle. Now turn off the heater, and let things cool down to about 50-60C. Then turn the heater back on and gently tug on the filament until it releases (while its heating up). Ideally, you want to pull a plug which has the shape of the inside of the nozzle at the end. Your nozzle should now be clear of any previous plastic, and the TPU won't be trying to push out old filament.

Also see: http://bukobot.com/nozzle-cleaning

[Vicky@Raise3D]

Please use our stock premium PLA to do clean step. It is more stable at a large temperature range.

[Billucas]

Hi Dhylands,

I have tried all your settings suggested and it does not work for me.
I used the cleaning rod from Raise3d before.
I manually pushed directly the filament into the hot-end.
The TPU came out, ok. I have loaded the TPU.
But when I start a print, after a layer or 2, I am doing air printing. I also can see the gear having trouble.
The gear is just beside the little pulley, can't be more closer than that.

Thanks for your suggestion and your help!
Luc

[Vicky@Raise3D]

Can you manually push the filament out when you find air printing?

[Billucas]

I am not sure what you mean, sorry.
When I manually push the filament it is because I take off the extruder cover.
After I saw that is my new TPU filament. So I put the cover back and I start loading filament on the touchscreen.
Then, I start a print process. After 2 layers, nothing more is coming out. I can see the gear having problem.
Do you thing that my extruder is not well ajusted for flexible filament? I tried about 20 times with different suggestions.
Luc

[Vicky@Raise3D]

Currently I'm not sure the problem is from hot zone or extruder.
What I mentioned is during printing when you find air printing after 2 layers, give the filament an addition force by your hand, and check whether the filament can be pushed out.
What does the gear problem refer to? Cannot bite the filament? Filament slipping?

[Billucas]

The gear is skipping steps. So tries to turn but returns to its increment. The force is to much for the gear to push
the filament down. Thank you Vicky for your help, I appreciate.
Luc

[Vicky@Raise3D]

So manually push the filament, it can be loaded out when air printing?

Is your cooling fans working properly at the side of hotend? Would you like to share some pictures of hotend?

[Julia Truchsess]

There is a lot of variation between various brands of flexible filament, and I have tried many. The most reliable for me has been Sainsmart. PolyFlex is also pretty easy. 245º extrusion temp recommended.

[Billucas]

The filaments tried are TPU filament from FILAMENT.ca and Polyflex. Both are not working for me now.
I took all the suggestions from Vicky, dhylands and John, but it is still not working. My N2 plus is new from last week.
It works good with PLA and ABS I used.
John told me that they tried Filament.ca TPU with success.
From now, I don't really know what to do for printing flexible. ( About 20 try)
Thanks,
Luc

[Julia Truchsess]

I've printed TPU successfully with the normal PLA profiles, but generally it is better to use slower speeds. And your nozzle needs to be perfectly clean. If you've used ABS before, you need to make sure all the ABS is out by purging it at 250º or so. Also make sure there is no tension on the filament at all - when TPU stretches due to tension/drag, it gets thinner, and then it slips. A long PTFE guide tube can add drag; overhead feed is best. Sainsmart spools are good because they have a small axle hub, which reduces drag thanks to increased torque.

[Billucas]

Here what Filament.ca suggested me. Witch I tried but doesn't worked for me.

Please increase your temp to 260c
We successfully print our TPU with the above mentioned settings on our N2 printer.
- V2 Hotend
- Latest ideamaker software with "Elastic Filament" template
- 260c temperature
- 80c bed temperature, either with buildtak sheet or glass with some glue on it.

[Evan]

What's your print speed?

[Billucas]

Hi Julia,
I used the cleaning rod from Raise3d before.
I manually pushed directly the filament into the hot-end.
The TPU came out, ok. I have loaded the TPU.
But when I start a print, after a layer or 2, I am doing air printing.
I also can see the gear having trouble.
Luc

[Billucas]

I've printed TPU successfully with the normal PLA profiles, but generally it is better to use slower speeds. And your nozzle needs to be perfectly clean. If you've used ABS before, you need to make sure all the ABS is out by purging it at 250º or so. Also make sure there is no tension on the filament at all - when TPU stretches due to tension/drag, it gets thinner, and then it slips. A long PTFE guide tube can add drag; overhead feed is best. Sainsmart spools are good because they have a small axle hub, which reduces drag thanks to increased torque.

Julia, you were right!!! I let the filament free, without the PTFE guide tube and I am at 50% print now!
I saw that it is hard to pull the TPU filament through this tube, like you said it makes restriction.
So I am really happy now, after many hours of debugging... Thank you very much again, and also
the other guys who suggested me things. Great support and community.
Nozzle 260c
Bed 80c
Free filament TPU
Clean nozzle before
Slow print speed
Luc

[NewbPilot]

Just curious if lowering the temperature of the nozzle would stop the leakage I have on my Ninjaflex. more retraction material? more amount of retraction?

Most settings are:
Fill 50%
Nozzle 225
default and min fan at 70%
retraction speed 26mms
Retracting 1mm
0.5mm min travel
0.02 min amount of retraction

For speed I have default printing to 20mm/s
inner shell at 40mm/s
x/y acist speed at 50mm/s
outer shell speed at 15mm/s
zaxis movement at 3mm/s
layer height 0.20mm
first layer height 0.30mm
first layer speed 15mm/s
first layer flow rate is 100%

[Vicky@Raise3D]

Leakage or Ooze? Strings?

It is hard to totally avoid strings for flex filament.

Take a try of 40mm/s retraction speed and 1.5mm retraction amount.

[NewbPilot]

I tried printing Ninjaflex again. I printed this GoPro case, a very popular case for people flying drones

http://www.thingiverse.com/thing:1583044

It printed structurally ok - the supports came out easily, which was fantastic. However, the walls dont seem to be connected to the face of the camera, and the walls and other parts can be literally peeled back (1st and 2nd pic). while the walls that were on the bed do seem to adhere (3rd pic). my settings copied under the pics

Filament settings:

slicer settings(here and in next post) in next post

[NewbPilot]

more NinjaFlex Settings