There are so many variables to juggle when using a 3D printer – temperature, design, workplace cleanliness – but few are as frustrating as filament problems.
Although I use ABS filament in my CubeX printer, lately I have been using PLA almost exclusively in my Cerberus 3D 250 and Gigante. The 250 uses 1.75 millimeter filament, while the Gigante uses 3 millimeter.
Yes, that means I have spools of both inhouse – open any closet right now, and you see spools stacked high. That’s especially true of the 3 millimeter because the Gigante sucks down filament like a hungry pasta lover inhales spaghetti. I now have a policy that, if I’m doing a large print, I must have a minimum of three five-pound spools to make sure I have enough filament from the same batch.
But that’s not the biggest problem with filament …. 
Just recently I was printing a pedestal for a project only to have the print stop part way. This time the problem was that the 3 millimeter filament, well, wasn’t 3 millimeters in diameter.
I got out my calipers and discovered that the print head had jammed because the filament was actually 3.2 millimeters. No wonder it wouldn’t feed!
If you’re using a 3D printer and don’t have a caliper (the instrument shown in the first photo in this post, you’ll want to get a set. You can get them from Home Depot, among other places.
Apparently, this isn’t an unusual problem. Sometimes the filament is out of round, too, and the nozzle just doesn’t like that.
Sometimes the filament is corrupted – we think that’s the source of the famous blue stripe in my sculpture Simple Planes With Aquamarine Stripe. In that case, fortunately, it created a happy accident, but that’s not always the case. This is apparently especially true with translucent filament, which I’ve found to be a little techy anyway.
A helpful article I read says it sometimes happens because manufacturers run other materials through the same equipment.
Of course, the overall problem is the youth of this industry. As things progress and mature, problems like crappy and inconsistent filament should work themselves out – those manufacturers who can’t deliver quality filament should improve their product or fall by the wayside. (At least we can hope so!)
Right now, though, I have to send some filament back ….