Need help with ninja flex

Hi, I am using a makerfarm prusa i3 8" with a magma hot end .40 nozzle. I have the 3mm ninjaflex in black and I am having a tough time getting it to print. I've been at this for weeks now trying to figure it out. At first I had it printing, but the prints had lots of skips in them. In other words the extrusion was not consistent, but it would make the piece. Then it started not making the piece and completely getting clogged. I would have to remove the filament, and maybe extrude some ABS through it, then start the flex again.

So then I decided to take my hotend apart again (PIA because everytime you do, you break the thermistor) and cleaned it out. I found some hardened material on the walls of the head, so I carefully picked it out, then I used cotton swabs on a dremel with polishing compound to polish the inside clean.

Oh, I had also modified my Greg's extruder by adding material near the hobbed bolt so that the ninjaflex would not get pushed out, instead of going through the extruder. Now I have a brass tube insert going up through my extruder, and the clearance to the idler bearing, and hobbed bolt is very tight. So after doing all that, the ninjaflex was coming out beautiful, better than ever. I thought I was good to go. The print started and everything was looking great. Then twice, and random layers, it would just clog again. I am printing at 225, on a 35 bed, and 20mm sec. Retraction is off, and all layers print the same speed. In the pictures below You can see a previously completed part, with the skips in it, and my last 2 attempts, which I cut with a scissors to see how well the layers were bonding. Got to say if I get this stuff to print right, it is an amazing material with TONS of usefulness. I actually made a functioning slot car tire with it.

After failing twice last night, I decided to put some ABS back in my machine, and right now it is printing better than ever. I started printing out some i3 rework pieces, and they look great. Possibly going to setup a 2nd printer because of the different materials I like to print in.

I really don't know what else to do. I just ordered a E3D HE, because I read that other people had success using it. I Was told by Fenner that my hot end should work.
Any help would be awesome.

You really need 235C for ABS and a bed temp of 100-110C

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Waitaki 3D Printer

I have the same printer and hot end and I run 110c Bed and 225c for the tip and it works ok, im thinking of trying 230-235 for the tip.
What layer height are you trying with those? Try getting good prints at .4mm and then dial it back from there. Im trying to get .2mm on my setup

Edited 1 time(s). Last edit at 01/02/2014 04:29PM by Floyd.

I guess I wasn't clear? I am having trouble with ninjaflex filament not abs. My abs prints are awesome. I print at 235-240 with abs. 225 with ninjaflex.
Before I cleaned my HE out I couldn't get the ninjaflex to extrude unless I was 260 or higher.

@Antslake,

Polyurethane, (Ether grade):

Drying Temperature:
Range: 80°C to 110°C, (176ºF to 230ºF)

Dry time:
Range: 2 to 4 hours.
Avg: 2.96 hours.

Glass-transition temp:
Range: -69°C to -17°C, (-92.2ºF to -1.40ºF).
Average: -40.2°C, (-104ºF).

Melting point:
Range: 110°C to 200°C, (230ºF to 392ºF).
Average: 151°C, (304ºF).

Processing temperature:
Range: 130°C to 227°C
Average: 199°C

Mold temperature:
Range: 15°C to 95.6°C, (59ºF to 204ºF).
Average 101°C, (214ºF).

Begin testing around this temp:
Substrate/bed/Platform temperature: 15°C to 40°C, (59ºF to 104ºF).
Enclosure temperature: 15°C to 40°C, (59ºF to 104ºF).

Machine parameters:
Extrude temp (RepRap): 215°C, (419ºF).
Platform temp (RepRap): 110°C, (230ºF), not verified.
Extrude temp (Fenner drives): 210°C to 225°C, (410ºF to 437ºF).
Platform temp (Fenner drives): 30°C to 40°C, (86ºF to 104ºF).

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I'm compiling a list of processing parameters for various polymers,
I don't know what type of polymer to look up for the Fenner drives NinjaFlex.
I'm assuming it's an ether grade?

Patent NinjaFlex:
Fenner drives said that they are going to patent their filament.
I didn't find a patent with a quick search.
[www.fennerdrives.com]

If you decide to contact the manufacturer for assistance, ask for the:
glass transition temperature,
type of polyurethane (e.g. ether grade),
is it hydrophilic,
drying temperature,
how long should it be dried for,
bonus if you can identify what fillers they are using,
and what they are using to make it low tack/low CoF (coefficient of friction).

It's interesting to note that Fennerdrives recommendations are low on the platform temperature,
and high for the processing temperature.

Edited 1 time(s). Last edit at 01/03/2014 02:03AM by A2.

I think what was happening is the filament is bunching up in the extruder. I did modify my extruder to not have a gap under the idler, but it is bunching up else where. I want to design an extruder specifically for this filament. Going to have to reduce the amount of distance between the hobbed bolt and the HE. Then find the optimal diameter for the 3mm filament.

The problem with shortening the distance is the gear. Using a gregs extruder. Gonna have to go direct drive or planetary gear. I have a few ideas. Gonna take some time to do though.

You may be interested in the modified Greg's Wade Reloaded extruder the Lulzbot guys are working on specifically for flexible filament. They're calling it the Flexistruder. They did print Ninjaflex successfully.

Development files are available here: [devel.lulzbot.com]

Forum discussion: [forum.lulzbot.com]

I had this same problem a while ago, I drilled out my extruder to fit a bowden tube all the way up to the drive gear so the filament is always constrained. it made it impossible to jam and wiggle out of line which also made it less likely to jam on all plastics.