Filament curling at nozzle?

You can't post links until you have certain amount of posts I think.
Do you mean this? http://www.instructables.com/id/Build-y … ry-Filame/

Nozzle doesn't seem much different from Filastruder.
I'm no expert but this is what I think is happening. What you describe seems like a problem which would happen if the cooling fan wasn't on or wasn't positioned properly. You want to cool the plastic which is coming out to prevent it from deforming (curling), if you don't then it will deform (curl) more than is needed because it will stay hotter longer.

Also, make sure there isn't any leftover plastic on the nozzle surface, it can act as a glue sometimes for the new plastic coming out.

This is just assumptions from my own experience, maybe it's something else.

EDIT: BTW is that a car window wiper motor? The extrusion is pretty fast.

Thanks for the reply guys!

Every couple of inches or so the filament will just curl back into the nozzle. Even after I have extruded a decent amount and it is laying on the ground.

I was actually one step ahead of you redbarret, I used a stainless brush trip on a dremel to clean the outside of the nozzle because I thought it was that too. And I tried to all different settings with the fan... I had the fan on the left, right, top bottom... didn't make a difference. I am wondering if maybe my thrust bearing isn't catching the auger and all the force is being put onto the motor. Maybe the fluctuation and load on the motor variances are causing a fluctuation in force inside the pipe and causing a curl. I don't know for sure... something to look into tonight.

And yes, it is a windshield wiper motor! The thing works great. Slow or fast, doesn't matter, and the thing has a ton of torque for this application. Scored it on eBay for 15 shipped. It is off a 99 Mercury Cougar.

That nozzle is different from the Filastruder's. It has an L/D ratio of about 1, whereas the Filastruder has an L/D ratio of about 15. In designing the Filastruder nozzle, I sacrificed speed in order to significantly improve filament quality.

This is likely leading to unstable viscoelastic flow, causing the curling that was mentioned.

Depends on the material being used. He talked mostly about using PC-ABS, which is very different from PLA.

I haven't designed a hotend, I'm not sure what you mean by that. I designed a nozzle for a filament extruder.

It is curling back onto the nozzle even after extruding several feet into the ground? I'd like to see photos/video because that's something I've never seen on a Filastruder.

I've tried high L/D nozzles and low L/D nozzles. The latter had measurably worse filament quality - like double the diameter variation.

But hey - if you think my thousands of hours of experimenting and testing produced incorrect results, try it for yourself! Be sure to share your findings...

Citation needed.

I am VERY conservative with my claims.

1.) Some folks report extrusion speeds 4-5x faster than I list on my website- users have reported things like 1kg in 3 hours, for example. Different polymers extrude at different speeds too - I've seen PLA extrude up to 10 times faster than ABS, for instance, but I am not going to list the best possible output speed as a specification.

2.) I list +/-0.05mm diameter variance on the website. Most users report +/-0.02mm, and some have reported +/-0.00mm filament variance. Again, very conservative claims, and dozens examples of independent verification.

I've yet to find a third party verification of any of the other extruders speed or filament variance... so please don't say things are "fact" that simply are not.