# Bulging filaments - How can catch them before they go in the printer

After multiple jams from bulging filaments on two spools I'm getting frustrated. One, right before a job was done.

Is there something I can do to prevent these bulges in filaments from ruining jobs?

What can I do to prevent this from happening in the future before it's a disaster?

He's a picture of one I found using google.

• What are you looking for in an answer? Do you reckon there is a better way than painstakinly physically inspecting the filament or just buying better quality filament to begin with? Jan 14 '16 at 6:54
• I'm not sure what you don't understand. I have two questions in the post. I can put them in here I guess. Is there something I can do to prevent these bulges in filaments from ruining jobs? What can I do to prevent this from happening in the future before it's a disaster? Jan 14 '16 at 7:03

That's my picture :-)

I use a filament monitor with an encoder wheel that pauses the print if the filament stops moving (because a bulge got stuck, or filament ran out, or the hot end jammed, or whatever). I have a bunch of these on multiple printers: http://www.toybuilderlabs.com/products/tunell-3d-printer-filament-monitor

The Tunell monitor works with Sailfish, Marlin, and Smoothie to my knowledge. This particular one doesn't work with Repetier, but you can wire up a simple encoder wheel to use Repetier's filament monitor functionality.

Like other people have mentioned, you should avoid cheap filament, and return spools with bulges. I personally only see bulges like that maybe every 20 spools or less.

• I couldn't get a good picture so pulled one off google. :-) hope your ok with that. Jan 20 '16 at 17:07
• No worries! Link to the original post if anyone wants it: plus.google.com/114722716901025057698/posts/aioDrYXYe3J Jan 20 '16 at 17:14
• That's why "The Google" has it. :-) I understand now. Jan 20 '16 at 18:33

How to catch and fix these on the fly? That would be difficult..

But this is an issue you really should not have.

Could it be an issue with filament storage?

Or is it coming from the manufacturer with these bulges? If so, I would try contacting ( you may have gotten a bad batch? ), or finding a new retailer if this happens often.

I have gone through a lot of pounds of both ABS and PLA and never come across this.

• I agree. I have never seen this myself. Jan 14 '16 at 7:42
• I can't determine where the incident occurs. In the supply chain? With my friends kid running around like a banshee? Who knows. I've just had it happen to me twice. A bit frustrating. Jan 14 '16 at 15:50
• Short of doing a bare eye inspection, or rolling out and rewrapping every single roll, I don't see how these could easily be detected when you first get them. My best suggestion would to get a plasticware tote and keep all of your filament in there. This will prevent them for getting moisture damage, and potential damage from being moved around often; if you keep seeing these, make note of on which filament, if they all came from the same place, or were all port of the same order, I would be contacting them for a refund / replacement. Jan 14 '16 at 15:54

Bottom line: The easiest way to prevent this is to avoid cheap filament.

You can get mid-grade filament for a few dollars more than the ultra cheap stuff.

In other words I tried out some 10$stuff from ebay, and while it might print for a little while it notoriously clogged in any prints greater than 1hr. 20-25$ is the going rate for mid-grade filament on amazon and check the reviews I've had good consistency there.

• There's a distinct possibility that something physical happened after I purchased it and it got into my hands. I don't have 24/7 surveillance on them. I know it's not my labrador because it didn't have teeth marks anywhere. Other than that, it's a mystery. :-) Jan 14 '16 at 15:51
• @Citizen could have been the humidity in the air too. I don't remember what all filaments are sensitive to that, but some are. Oct 8 '16 at 6:00
• @BrainSlugs83 maybe the Labrador was standing there breathing on it. My dog stands and sniffs this stuff for as long as we let her ... Oct 18 '16 at 18:54

There is a filament width sensor design at http://www.thingiverse.com/thing:454584 -- cleverly, the author tweaked Marlin so it adjusts extrusion in real time to correct for variations.

That said, I agree with several others that buying filament with better quality control, and keeping it dry and unchewed by Labradors, should be enough. :)