Best method for replacing filament?

I'm about to test the first spool of PLA filament other then the green sample from the kit. I've had to remove the green filament a couple of times during the building process but I still feel a bit insecure of how to do this in the most gentle way for the machine. One time I turned on the heater from pronterface and it was set to PLA 220 C and then reverse extruded 100 mm. The filament seemed to come out fine with a thin thread at the end. Another time I tried to do it another way by setting the heater to 80 C and then reverse extrude because I read that this was a good method because the pla becomes rubbery but doesn't melt. But doing it this way I had to pull really hard when the deformed part of filament met the hobbed bolt. It even lifted the machine off the tabletop. I got it out in one piece but this method seemed very rough on the machine. How do you go about this?

Niels

I usually just snip off the current roll, then feed in the new one. You need to manually extrude a few tens of mm's before the new stuff starts coming through, but otherwise it is painless.

I did the 80 degrees, reverse 150mm at 100mm/second method straight from the Build Manual.

I found it needed continual, steady, leverage and the filament just seemed to keep coming. I was a little surprised to see the thin section and did wonder if it would break but continued pulling resulted in the final plug of filament popping out.

For a first time of doing this I was more than a little nervous but I will be a lot more at ease next time.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

I heat the filament to 85-90C, wait a short time if going from a cold start in order to let the heat do its softening job and then wind out the filament by hand by turning the large gear. That gives me more control compared to using Pronterface (...or Repetier ... or Octopi).

Alan

Edited 1 time(s). Last edit at 10/31/2013 02:49PM by Alzibiff.

Thanks guys!! Hey Neil, I got that thin section too, and thought I got very lucky it didn't break. Besides the use of force, this was another reason a got a bit scared using this method.

It is best if you pull it out in one continuous movement. Otherwise you can get a section solidify and be too big to get through part of the extruder. Because it stretches when above the glass transition it needs to rewind a lot further than the length of the extruder. That is why I use 150mm and it is important to pull it as soon as the bolt looses grip and not let it stop.

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It's funny that a bunch of us all seem to be at the same rate. I'm also just about to run out of the Vintage Green. Going to play around with ABS tomorrow

Aha ABS...I'm going to postpone the use of that filament until I'm really comfortable with PLA. I'm dreading the infamous warping and bed adhesion issue too much right now. But go boldly though!

Edited 1 time(s). Last edit at 10/31/2013 08:15PM by Nilez.