Why do my prints suck?

I'm using pla to print my objects. I've printed a few pieces that turned out decent at aruond 210c. Recently though when I print at 210 my extruder starts skipping a lot and lines look more like dots. I turned it all the way up to 235c and it seemed to print lines better but smaller pieces that stick up it just does a terrible job. I've tried lowering the heat as well and it starts skipping more.

The only way it prints perfectly is if I force the filliment into the extruder. I've even tried unrolling a piece of filliment and holding it to reduce the amount of work needed to feed the filliment and it was having the same issues. Can someone please point me in the right direction on this one as it's driving me crazy.

Ohh one more thing I printed a piece and it came out pretty well. I then printed the same piece using the same gcode and it came out poorly. Since then is when all the problems have been going on.

Have you checked your idler tension and hobbed bolt? When filament strips its likely that it will leave chips in hobbed bolt grooves that negatively impact grip. Also check if there isn't some debris inside hotend partially blocking nozzle.

It would be useful to report what hot end you use. Also do you cool its upper section with a fan? It seems many hot ends require it for PLA, otherwise you can get symptoms like you're having.

Also, what size of filament do you use, 1.75 or 3mm ?

Not long ago I had problems with the filament requiring more force to extrude than usual, and spotty results, with many filament jams, cleaning up the hobbed bolt and changing the idler pressure didn't help. I ended up removing the nozzle and letting it sit in acetone for a few hours. This solved my problem, but it might not be relevant to your situation: I print exclusively ABS 3mm.

I learned one thing that may have cause this: apparently hot ends don't like to sit idle at high temperature with filament in the chamber. Since I got my printer back in January I used to start heating up the hot end and the bed at the same time, only the bed takes a lot longer to reach its temperature, so the hot end was sitting there for at least 10 minutes. Now I start heating the hot end only when the bed has almost reached its temp, and as soon as the hot end reaches its temp, I start the print.

I have a j-head hotend. I print in 1.75 pla only.

I did turn on my hotend and left it sitting for a good 3 hours before I realized I had it on. It's right around the time when these issues started too. What would be the fix for this issue acetone as well?

i have used this method to clean a makergear hotend http://www.youtube.com/watch?v=6bTfl35zlHE

Acetone works really good to unclog nozzles. The only other way to unclog a nozzle is with a blow torch and a lot of patience. Of course, you'll need to disassemble your hot end, which may be a bit of a hassle, but, I've found it's ultimately easier and less time consuming to clean it out than to try and make it work. Jams are like abortions. You never want one, but it's better to deal with it early.

ohioplastics Wrote:
-------------------------------------------------------
> Acetone works really good to unclog nozzles. The
> only other way to unclog a nozzle is with a blow
> torch and a lot of patience. Of course, you'll
> need to disassemble your hot end, which may be a
> bit of a hassle, but, I've found it's ultimately
> easier and less time consuming to clean it out
> than to try and make it work. Jams are like
> abortions. You never want one, but it's better to
> deal with it early.


im a bad man that last part made me laugh.

I got it from Argo. Ben Affleck, awesome dark humor.

Edited 1 time(s). Last edit at 08/01/2013 08:15PM by ohioplastics.

I was able to fix the issue. I removed the filament and heated the hotend up to 240. I then took the filament and ran through 100mm in a very short time. I then removed the filament turned off the hotend and cooled it with a fan to drop the temp quickly.

It seems to have worked and is printing just fine again.