If you do a little searching around on the Web, and if you look at the product reviews on sites that sell 3Doodlers, a pattern emerges. There seem to be three major groups of 3Doodler users:
1. Squee! So excited, having so much fun!
2. Wow, this is interesting. Harder than I thought, but if I spend some time with it, I bet I can do some fun stuff.
3. Horrible! It jams all the time and is unusable.
(There is a fourth group: "I bought this for my eight-year-old and he can't instantly create perfect works of art. Must be the pen's fault." This group Does Not Count.)
So, it appears that there may be a consistency issue in the manufacture. Some pens feed and work fine most of the time, and some jam very frequently.
I got one of those.
However, rather than complaining or trying to return the pen, I decided to try to understand the feed, and why it might be jamming so much. This instructable is about what I found, and how I improved my filament feed reliability.
Step 1: Lots of Jams
Step 2: Open the Maintenance Cover
The maintenance cover forces the filament to within reach of the screw threads, and the turning screw drags the filament down to the heating element.
What I kept seeing in jams was the filament off track to the "down-wind" side of the screw ... the right side in this picture.
I neglected to take a photo of it before, but the metal slide on my pen was pretty wide. It was clearly not constraining the filament enough.
I grabbed my Leatherman and squeezed the wings of the slide together a little. A little too much, actually. The filament was catching on the leading edges of the slide after my vigorous adjustment. Sorry, again no pictures. I was working this out, not thinking about documenting the process, yet.
Step 3: Getting Just the Right Spread on the Wings ...
So, looking around, I saw the plier jaws on my Leatherman. I grabbed another pair of needle-nose, balanced the metal slide on the tips of the Leatherman, and applied very gentle pressure. The shape of the pliers gave just the right pressure to separate the wings of the slide, and I ended up with a perfect fit.
I put it all back together, and since then have had almost no problems with jamming.
I would love to hear from you in the comments if this helps you at all, or you had different issues with your 3Doodler 2.