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celso-santos

Feeder skipping

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My U2 printer now is regularly skipping. It makes that "squeak" sound and prints nothing. Then I check the nozzle that seems OK, move some material, what works right and then, when I try to print something, the printer head starts moving around but no material comes out of the nozzle.

Sometimes I change material and after 7 trials I can print something, but then the problem happens again and I have to go through the same litany one more time.

The "squeak" sound keeps on happening and I don't know what to do.

Should I tighten the feeder? How do I do that?

Celso

 

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I don't know what's going on. Could it be that the knurled sleeve is slipping on the feeder shaft? Would that make the squeak? Look at the feeder carefully - is the shaft turning? Is the sleeve turning? Is the filament getting ground up? Maybe the squeak is filament being ground to dust?

I don't use the "change filament" feature anymore. It's much more informative to change the filament by hand.

1) Turn your printer off and then on to make sure there is no power on the feeder server.

2) Warm the nozzle - if removing filament set the temp to 100C. If inserting filament set it to 200C.

3) When the nozzle is over 95C you can just grab the filament and pull hard. It should get everything out of the nozzle including dirt and dust. Possibly the tip breaks off in the feeder - this is bad news as you have to now fish it out. This hasn't happened to me yet.

4) Before inserting new filament cut the tip so that it is strong and pointed. Pointed so it feeds well. Then just shove it in the bottom of the feeder pretty hard - once you get past the feeder it gets a litttle easier until it hits the head. Now you have to push very hard (10 pounds force minimum) to get it to extrude by hand but make sure at least a little plastic leaks out.

 

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Installing the filament yourself will help you notice problems like a jam in the bowden or a loose sleeve or a clogged nozzle.

 

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The squeak is from the filament being pulled against the body of the extruder as it's moving through. I think your issues are down to filament not having a smooth enough route. I had these issue, I switched to filament off of the role and it feeds perfectly now. Completed a 22 hour print unattended with zero issues.

 

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I watched the video and there is no squeaking as I would describe it. The squeaking that fingerpuk thought it was (as did I from the description) is much louder than what you're hearing. The sound you hear at 8-10 seconds in the video is retraction, this is normal and prevents stringing. It pulls the filament back a short distance to relieve the pressure in the nozzle before moving the head, then it moves the filament back to continue printing.

At 14 seconds into the video you have a skip back. This means that the motor is trying to push filament through the nozzle but the resistance is too strong so it skips back a few steps, this is intentional. The cause for it can be different things but I would start with what gr5 describes to get rid of any dirt in the nozzle as a partial clog could be the problem.

What are your print settings? I'm not sure but it looked like you were trying to extrude fairly fast in the video.

 

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I am printing at 60mm/s with .06 mm in layer height. Temperature is 220ºC and plate is set to 60ºC. The skip back at 14 sec. is what I was talking about.

Maybe there is a partial clog in the nozzle, but if that was the case I would not Move Material from it so easily, don't you think? Any options to rule this out without disassembling the nozzle?

 

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Ok, then that's not the issue. I would suspect a partial plug then. Do what gr5 described and try again. If it's still not working you could try sticking a thin piece of wire into the hotend (while hot) and try to dislodge whatever is in there. Make sure it's thinner than the nozzle (0.4mm) so that you don't widen the hole.

 

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Oh - the skip back! Yes! This is a very common problem. Is it printing right up to the moment before it skips back? Or is it not printing for many minutes?

1) Stops briefly. If it stops printing only briefly (right after skip back) then this is a very common problem but has many possible causes. You might need to replace or remove and drill out your white isolate located just above the nozzle. Putting your filament on the floor would help quite a bit.

2) Never prints. If nothing is coming out of the nozzle just before the skip back then you probably have a clogged nozzle. The "atomic" method is the easiest method to clean:

First heat nozzle to 150C (hotter is okay) then set temp to 90C. Once the temperature reaches 90-95C pull hard on the filament near the feeder and pull it all the way out. Cut off the end and throw away. Cut the end to a point and insert the filament back in, reheat to 180C and push on the filament. If it is still clogged repeat the process and also maybe also insert a needle into the nozzle tip (hypodermic or acupuncture). If it doesn't remove gunk from the tip, try slightly cooler or warmer temperatures when you pull (like 88C or 92C).

If you explain your problem is #1 then we have more advice as #1 is common and has several solutions.

 

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Well, the problem is that sometimes I can print just OK like now, after I changed again the filament. This time I am being able to print perfectly. This filament I am using is from Ultimaker. Some of other filaments are probably chinese, sold here by brazilian companies. These filaments have a ø 3mm rather then the recommended 2,85mm from Ultimaker. Could this be the problem?

The point is that many times I can print perfectly with them. Then, when I try to print something else, even using U filament but nothing happens.

Can you print anything you want reliably each time you want?

If the point lies in using the right filament, I've just ordered a bunch of new ones and will forget any other options.

Thanks for the help.

Celso

 

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Making sure you have 2.85mm filament and not 3mm will probably help a lot. I'm not an expert but i guess this can lead to partial clogs and cause your problems.

There's also probably more friction in the bowden tube with the 3mm filament that can cause the skipping i guess?

 

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Finally I am getting closer to the truth! Check the image of a natural PLA filament as it went out of the nozzle in one of my Move Material trials. I think that the small black dirty spots are still traces of the black ABS filament that I experimented some time ago. It didn't clog my nozzle but remains of it may be the cause for an unstable behavior of my printings.

Dirty Filament

 

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I think you may have a similar issue to what is happening to my prints. Check out the link, but basically after switching from ABS back to PLA or vice-versa, if all of the plastic isn't purged well enough it either doesn't get hot enough to melt and extrude (ABS) or it carbonizes on the walls (PLA) because of the temperature difference when printing the two.

Overall however what this really is doing is introducing more friction (in the way of pressure) into the system, which includes friction from the bowden tube, the filament/spool, teflon spacer, etc. all working against the force the feeder stepper can provide. Reducing friction anywhere and/or everywhere else should help in preventing the dreaded 'feeder skip'. Also reducing the print speed and raising temperature a few degrees seems to help as well.

I'm actually printing IRobertI's low-friction spool holder now. (reallly really slowly)

http://umforum.ultimaker.com/index.php?/topic/9295-switching-between-pla-and-abs-thoughts-on-under-extrusion-clogging-burnt-pla/&do=findComment&comment=90051

 

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