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Author Topic: Slow extruder issues....  (Read 441 times)

sjensen

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Slow extruder issues....
« on: February 06, 2014, 01:17:01 PM »
So the quality of my prints started to drop a few weeks ago, after having not used my bukobot for a while.
I think I've tracked the problem down to something to do with the extruder?

After printing the first few layers successfully, the prints become a weird, spongy spider web of plastic instead of the solid shapes they should be.
Some prints will get quite a way in before the issue creeps in but with others its apparent sooner, although it seems like its getting worse.
For some reason solid, simple shapes haven't been exhibiting this problem to the same degree as more complex organic shapes.
The issue seemed more apparent on support material as opposed to the main body of the print when i first started to notice it.

I used to do a manual extrude and get fast thick streams of plastic that zipped out, often forming a plastic cylinder.
Now when I do a manual extrude from repetier host it is an incredibly slow, thin stream of plastic that takes a long time to finish extruding, even for a small amount. The stream of plastic hardens in a straight line from the tip of the nozzle it moves so slow. I can imagine if it was extruding like this when it should be extruding like it used to, that would explain my current prints.

This originally lead me to believe that it was a clogged nozzle, a problem with the stepper motor on the extruder or something in that vein, something physically wrong with the hardware of the printer.

BUT.....

My machine has always done intermittent extrusions once the extruder is heated past a certain point. It still does these random extrusions and they are fast streams of plastic, just like they should be!

At first I thought it was slic3r giving me issues but I've run gcode from Kisslicer and had the same problem.
I've had the problem with repetier host 0.95f and also 0.85b.
I've tried re-uploading the marlin firmware, as well as a few other things but the issue persists.

I'm pretty stumped, any ideas would be much appreciated!
Thanks,
Sam

sjensen

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Re: Slow extruder issues....
« Reply #1 on: February 07, 2014, 10:42:29 AM »
So I hadn't noticed that I had the manual extrude speed down really low  :-[
This explains the difference between the automatic extrusion and the manual extrusion.

I've taken apart part of the extruder and there are marks on the plastic from the teeth that I can see now, so it is getting held up sometimes.
The stepper motor works with out any issues.
I did try a brand new nozzle so not sure if it could be a blockage causing the issue?

I suspect that it might be a temperature thing?
I think the hotend is cooling down to the point that it can no longer extrude filament properly.
That might explain the intermittent nature of the problem, why it works sometimes and not others?
It could also be that I'm running the temperature at the lower end of things (187 degrees). If the reading its picking up was out by 10 degrees that could screw things up.




sjensen

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Re: Slow extruder issues....
« Reply #2 on: February 09, 2014, 11:15:08 AM »
It looks like I've managed to fix the issue somewhat. I figured I'd share the solution here just in case others find it helpful.
I think my actual problem was what a lot of this thread was about:

http://forum.bukobot.com/index.php?topic=2966.30

These are the changes I made that seemed to have solved the issue, not sure which one it was, could have been a combination of things so I might do some more testing to find out.

- increased the temperature to 205
- loosened the screw suggested by whosawhatsis
- lowered the retraction setting from 1.9mm to 1mm
- Changed from red diamond age PLA that had been sitting around uncovered for months to some yellow diamond age PLA that had been kept in a plastic bag, in a drawer since it was bought. I noticed a few people who were having issues were using the diamond age pla. The red and yellow PLA apparently use the same pigment carrier but I'm not sure what other similarities or differences they have.

 

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