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Topic: Extruder not clogged, still jams.

Hey everyone, I have come here to ask for help. I have been troubleshooting the issues my Solidoodle 4 has been having and am a little stuck at the moment. It started when my prints started to fail and I thought the extruder may be plugged. This was not the case as I inserted a scope camera after cleaning it and found it to be clean. The prints started having gaps where no ABS was extruded. I observed closely and can visible see a part on the extruder skipping. I have included a stock photo of the model extruder I have.

  The gear on the left has teeth and the bearing on the right is smooth. It is the bearing on the right that I can observe sticking. As the side with the teeth continues to move, the opposite side stops moving and the filament stops feeding. This causes the side with the teeth to grind into the filament and even nearly cut it in half.

  I am curious if there is any common reason why this happens and if there is a solution I can do without ordering a new part. I am using Blue Solidoodle Abs. I am curious if I may need to adjust the bearing and spring but am not sure how to properly do so. I have attempted adjusting the screw directly under the spring and on and above the bearing though I don't know for sure if these do anything for adjustments.  I have spent hours pouring over the internet looking for answers with no success. All I have been able to do is narrow down he problem. Any help is appreciated, thank you.

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Re: Extruder not clogged, still jams.

Check your temp chart and ensure it is stable.  You may want to come up with a way to increase the spring tension also.

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Re: Extruder not clogged, still jams.

My temps are stable, the temp doesn't appear to be the problem as if I manually extrude it works flawlessly at fairly high rates. The spring tension has been what I have been thinking as well but have no idea how to add to the spring tension on the solidoodle 4 printer nor can I find any tutorials.

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Re: Extruder not clogged, still jams.

Fold up a piece of paper and use it to shim the spring. You won't need much. 1-2mm thick should do the job.

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Re: Extruder not clogged, still jams.

Also. make sure the pivot screw is not overtightened as this would limit the ability to pivot freely and apply the appropriate pressure.

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Re: Extruder not clogged, still jams.

I have tried all of this with no real success. I have tried each screw in every varied position of tension, the bearing still skips. I have taken the entire assembly apart, inspected, and reassembled it. I just cant seem to locate the issue and I have had to stop printing for the time being. On the bright side I am beginning to know the machine really well but I still cant seem to solve the issue. I have cleaned the hot end several times and know definitively that it is not clogged but I have noticed that is does take a fair bit of force to push the filament through by hand. I have also tried adding to the spring tension which didn't work, the only thing I see that is messing things up is the skipping bearing.

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Re: Extruder not clogged, still jams.

Check your hobbed pulley and ensure the teeth are clean.  If you stripped some filament the teeth could be gummed up.

8 (edited by TjayAj. 2015-01-21 17:25:24)

Re: Extruder not clogged, still jams.

I have tried this as well, Actually I have been having to do that every time I use the system lol. Its been quite messy trying to print lately so the entire unit gets cleaned regularly.

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Re: Extruder not clogged, still jams.

Thought I had it fixed by adding even more shims to the printer but this failed after twenty minutes and the grinding issue returned. To isolate the problem I will be switching out parts one by one with parts off of my second printer to ensure I am working on the right areas. First test will be the extruder head because it is one of the easiest to fix and replace. Maybe I missed a clog that the camera didn't notice.

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Re: Extruder not clogged, still jams.

After replacing the extruder and the entire arm I still faced the same issues. Upon letting a friend of mine who is a professional in the plastic industry take a look at the unit, his belief is that though they don't appear to be with the naked eye the teeth that feed the filament may be stripped. How could I get a  few replacements of this part and how much would it cost me?

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Re: Extruder not clogged, still jams.

It's pretty unlikely that is the case, and if you can't see it with the naked eye I would say even less so. How well are the hobbed gear and bearing aligned? How well is the gear aligned with the hole of the PEEK barrel? Do you have the pivot screw of the extruder so tight that it cannot fluctuate with variations in filament diameter? This issue can be extemely frustrating but I can assure you that whatever the cause is, it will be easy to fix.

If you want to solve this for good put a different extruder like the mk5 on there. I've posted about how to do this on an sd4 numerous times so have a look at my post history. Unfortunately the SD4 aluminum extruder is not very good and it won't serve you well forever.

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Re: Extruder not clogged, still jams.

IMHO, if the filament is unusually difficult to push out, I'd investigate the nozzle and filament path, as stripping at the gear would be just a symptom of that, not a cause.

Maybe your thermistor is a bit off.  Have you tried bumping up the temperature a bit?  Also, if the clogs only start occurring after you've printed a bit, check to make sure your extruder is not getting too hot.  The fan on the back of my SD2 extruder used to stop every once in awhile (until I replaced it with a better one) and that would eventually cause filament to start sticking in the PEEK mid-print.

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Re: Extruder not clogged, still jams.

I have this exact problem.  It is as if you were channeling my thoughts.

Have you found a fix?  I am still struggling and very frustrated....I had been running nearly flawlessly for several months and then changed filament for the first time and whammo...nothing but extrusion problems.  It usually starts printing the base layer OK, but as soon as the print speed picks up, it starts missing and skipping.  It is as if it cant keep up with the higher flow requirement without skipping and grinding the filament.  I have tried 3 different roles of new filament with no change in behavior.

Anyone have any ideas?

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Re: Extruder not clogged, still jams.

Are you trying to print ABS or PLA?
What temps are you running?
Also, this has already been discussed, but have you adjusted the tension?

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Re: Extruder not clogged, still jams.

Change the wiring that comes from the board to the extruder. I guess it is a bad wire problem. It might be broken from inside.
Depending of the position of your extruder, your cables change position and at a specific position, if one of the wires is broken from inside, it just makes a noise and tries to go back and forth and does not extrude. If it extruder at the home position and not on the bed, this might be the problem.
i am having the same issue and whenever it stalls if i reposition the cables coming out from the extruder, it starts to works again.
it is just my humble opinion, i am not an expert but you should give it a try.

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Re: Extruder not clogged, still jams.

This is the exact symptom I had when my hotend got clogged and the extruder couldn't push the filament through it.

/*
As the side with the teeth continues to move, the opposite side stops moving and the filament stops feeding.
*/

You've go this backwards.  8*)  It's not the right-hand (free-wheeling) bearing sticking, it's just that the filament isn't feeding, so the bearing doesn't turn.  I put a mark on my drive gear so I can see when it's moving, and I can watch the bearing to ensure both of them are moving when they should.

I cleaned my hotend several times to no avail, finally had to completely disassemble it and burn it out with a torch.

You say you've already replaced the hotend?  Has the cooling fan on the left of the assembly stopped spinning?  They use fans with a lifetime measured in months, so pull it apart, remove the sticker, and put a small drop of light machine oil on the bearing.

What are you using for a spool holder?  Could that be jamming up and preventing the extruder from being able to pull the filament?

The SD4 sure is an educational experience, isn't it?  8*|