What causes these kind of print errors?
This one is for all you forensic 3d print investigators out there. This photo shows an example of artifacts I often get on the back of my models on otherwise good prints. These horizontal gaps seem to correspond to where each perimeter begins since I have my start point fixed on the back of the model to hide the seam. This doesn't always occur, only about 25% of the time...and usually starts later on during the print. I'm printing at 0.1mm layer height and 30mm/s using PLA on a Dremel Idea Builder.
Re: What causes these kind of print errors?
It looks like an extruder problem to me, specifically like the extruder mechanism is not able to feed filament at the rate requested by the GCode. I had this problem once with a spool of filament that was wound improperly - it was wound on the reel too tightly, and it also had many overlaps that would cause the extruder to get stuck and not be able to feed properly.
I fixed the problem by rewinding all the filament onto an empty spool.
I fixed the problem by rewinding all the filament onto an empty spool.
Re: What causes these kind of print errors?
Could feed resistance from the spool account for the pattern here? It always starts later on in a multi-hour print and is focused where each perimeter begins.
Re: What causes these kind of print errors?
Another thing to check: if your printer has a Bowden tube extruder see if there is a slight kink or bend in the filament that you feed into the tube. I had that happen to me just today - a brand new spool of filament had a slight bend about 18" back from the end. I was able to get it through the tube and into the hot-end OK, but the kink provided enough extra friction inside the tube to prevent the extruder gear from feeding filament properly.
The fix was easy - I just pulled out the filament and cut off the the first 2 feet or so. After that - no problems at all.
In your case it looks like there might have been a small kink much farther in. The only way to check for this would be to re-spool all the filament onto an empty spool, checking for kinks as you go.
The fix was easy - I just pulled out the filament and cut off the the first 2 feet or so. After that - no problems at all.
In your case it looks like there might have been a small kink much farther in. The only way to check for this would be to re-spool all the filament onto an empty spool, checking for kinks as you go.
Re: What causes these kind of print errors?
Its resistance in the feed...somewhere. That could be in the feed tube, extruder or hot end. Since it happens later in the build i would take a guess and say you have aome heat creep issue there. When the heat gets too high in the hot end then you jave too much melted plastic to push which causes resistance.
Re: What causes these kind of print errors?
Another possibility could be the filament jamming in the extruder threaded tube..possibly during a retraction cycle. I had this happen recently...and the only lasting solution was to fit a new tube. And it was a complete strip down to change it!! 
The early symptoms I had was the filament failing to extrude at the start of a print job...occasionally at first, the frequently...then the lace netting effect you have at random places in prints.
The early symptoms I had was the filament failing to extrude at the start of a print job...occasionally at first, the frequently...then the lace netting effect you have at random places in prints.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
Re: What causes these kind of print errors?
Any drag on your filament will do this. It may be tightly wound (pinched between layers) on the spool. It may have kinks so it's not going smoothly through tubing. The tubing it goes through may have stress on it at particular heights (stretched over a cover). Dirt in the tube causing drag on the feed. If it has any dirt/oil on it, the feeder may be slipping. Or spool is not rotating freely/smoothly.mitchfx wrote:This one is for all you forensic 3d print investigators out there. This photo shows an example of artifacts I often get on the back of my models on otherwise good prints. These horizontal gaps seem to correspond to where each perimeter begins since I have my start point fixed on the back of the model to hide the seam. This doesn't always occur, only about 25% of the time...and usually starts later on during the print. I'm printing at 0.1mm layer height and 30mm/s using PLA on a Dremel Idea Builder.
Re: What causes these kind of print errors?
if i remember right doesnt the dremel have extruder issues concerning heat creep among other issues?
