1 Topic by jamesh (edited by jamesh 2012-12-16 17:25:37)

  • jamesh
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Topic: Extruder grinding filament and then skipping

So I just got my Solidoodle 2 this weekend and I've been having problems out of the box sad

I started using black ABS (from Solidoodle) and noticed that the extruder gear head would grind the plastic off - it still extrudes, but every rotation or so it skips because of plastic build up in the teeth. I've tried cleaning out the junk multiple times but it always seems to happen no matter how loose or tight I adjust the bearing wheel. I've been running it at 200C, also tried a bit hotter and a bit colder to see if that would make a difference.

It seems to me that the extruder gear's teeth are way too sharp because I haven't been able to successfully print anything yet sad

I have tried flossing the tip with some 32ga wire (all I had), might see if I can find a guitar string because that would work better...

Any ideas?

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2 Reply by Tomek

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Re: Extruder grinding filament and then skipping

you probably have a clogged printer head. When you say you've tried cleaning with wire, what do you mean?

The way to clean the head with wire is to stick up from the nozzle-exit a piece of thin wire and move it around. Usually you have to feed the first few mm of wire in a very small piece at a time, or else the wire will bend if you don't grip it near the tip.  The nozzle has to be at temperature, of course (cold nozzle would have hard plastic so wire couldn't slip in.)


Also, how "squished" is your first layer? I've started developing a clogged nozzle recently because I keep oversquishing my first layer. I dialed that back a bit, and have better results now. I also developed a clogged nozzle because my filament spool was getting stuck while I was gone, resulting in the filament breaking, and ultimately I would have my nozzle running without filament flowing at full temperature for the next several hours before my printer thought the print was done. In other words, leaving the nozzle at full temperature without filament flowing is  bad.


You should also look at the solidoodle wiki about cleaning a clogged nozzle.

3 Reply by jamesh

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Re: Extruder grinding filament and then skipping

Thanks Tomek,

I switched over to white ABS and have successfully printed a few parts (mini batarang, some thumbscrews for the Z adjustment etc) -- doesn't seem to be grinding anymore. Lots to learn, but I'm happy it's printing stuff smile

4 Reply by IanJohnson

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Re: Extruder grinding filament and then skipping

This might relevant, from the Google group-

Hello Solidoodlers!

This is TJ from Solidoodle. After hearing and reading about clogging issues from our black filament, I thoroughly tested a few known "problem" rolls of filament that were sent back and initially had similar results. At first, I too believed it was clogging, which in turn was causing the drive gear to to shred the filament. After some experimentation, I noticed the drive gear was shredding the filament, but I could still easily push the filament through, which ruled out a clog. This lead me to believe that rather than the filament being 'bad,' It just needs different calibrations.

1) The black filament is generally softer than other colors making it more prone to shredding. When this happens the filament no longer pushes through via the drive gear, which may look likeWhen I tightened the idler swing arm on the extruder, the filament stopped shredding, but the motor would periodically skip steps. Which leads to:
2) The melt temperature for good extrusion is almost 10 degrees hotter with black filament than other colors. My hot end is set at195C for our blue/green/red/natural, but for the black I use 205C. To solve this issue, I tested the black with PID off which causes a sinusoidal temperature swing of about 10 degrees. I set extrude amount to 100mm and observed that at the lower end (190C-195C) the extruder motor would skip steps, yet at the higher end (195-200) the motor would skip little or none.

Essentially, If you think you have problem filament, give the following a try before tossing it.
-First, tighten the swing arm, but make sure you leave the spring enough room to compress. Otherwise the extruder will not be able to compensate for variations in filament diameter.
-Increase your temperature by 5-10 degrees. Don't push it to high (210C MAX) otherwise the barrel might become hot enough to soften PEEK retainer.
-Lower your print bed and extrude 100mm of filament. If the filament comes out smooth without any skipping or shredding you should be good to go. Try printing a couple small parts as a test.

I will not say this will fix issues for everyone, because I simply don't have a sample of everybody's filament. But it has worked with all the problem filament I have tried so far.
If you want to give your problem filament another go, follow these steps and respond with your results

Cheers.
TJ

5 Reply by jamesh

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Re: Extruder grinding filament and then skipping

Switched back to the black ABS... worked fine for one print, now its grinding again...

6 Reply by jamesh

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Re: Extruder grinding filament and then skipping

IanJohnson, thanks! I shall try that right away smile

7 Reply by jamesh

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Re: Extruder grinding filament and then skipping

Worked like a charm, thanks so much! I spent a few hours searching the forums but never found that post. Incredibly helpful - should be in the troubleshooting FAQ on solidoodle smile

8 Reply by jamesh

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Re: Extruder grinding filament and then skipping

So it worked for one small print, but then when I tried a larger print I found the extruder temp would drop to 190 or less while printing the raft... the raft tends to use more plastic right? Is there a reason the extruder isn't keeping up with the set temperature?

Not too sure what to do now other then switch back to white plastic again!

9 Reply by HelmutK

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Re: Extruder grinding filament and then skipping

Check the "Temperature" settings in Skeinforge. Even if you manually set a temp it can change based on these settings. The black abs may need more than 190c to print properly. Also note that when it is printing slowly it may reduce the extruder temp a few degrees.