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nathan-peterson

Feeder skipping regularly

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I have had my printer for about a month I think. My prints have been decent except for the feeder skipping which causes lack of extrusion during parts of the print. This happens fairly regularly. The nozzle seems to be extruding fine although I have tried manually shoving filament into the extruder at 260 degrees to see if there was anything that needed to be cleared out. I also tried taking apart the feeder and cleaning it. None of those things have helped. The problem seems to get worse if I go above 50 mm/s or increase the layer thickness (the problem is also more likely to occur on the first layer since that is thicker). Any ideas of what I should do?

 

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what is your extrusion rate? Take the layer height * nozzle width * layer speed. For a UM1, it seems the magic number is < 5mm3/sec Not sure about the UM2. So for my UM1, for a 0.2mm layer, I try to stay below 60mm/s (0.2mm * 0.4mm * 60mm/s = 4.8mm3/s) if I understand things correctly...

 

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if you have a lot of retraction points in each layer, the feeder might have flattened a portion of the filament and cant grip it well enough to keep up. If thats the case, decreasing the length of retractions should help. I've had this problem several times before.

 

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Do the atomic method several times it should clean it, using a small needle is always a good help.

For your main problem about the feeder skipping, it might come from the filament you use.. what is the brand? Are you sure it's 2.85mm ?

A partially clogged nozzle could also explain this or temperature too low.

 

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It is ultimaker brand filament. Right now it is really clogged. I have tried the atomic method many times yesterday and today. It won't budge. The filament seems to be melting fine though. I don't think it's a temperature problem. Not sure where I'm going to find a small enough needle. That hole is really small.

 

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Were you using PLA? If you are really hosed, take the nozzle apart and blow touch it. I just use a gas stove and put the nozzle directly in the flame. PLA burns out easily. Not sure about ABS.

Of course there is some risk so only use as a last resort.

Some people say they use a hypodermic need for cleaning the nozzle.

 

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I tried electric wire actually. I tried multiple sizes of wire. I even have some extremely small electric wire that is used for wire wrapping which is either not small enough, or just wouldn't go in because it's blocked. I guess I'll try taking it apart. I think I have a blow torch in the garage too.

 

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My printer is having this skipping problem again, although now it's really bad where I can't print anything because it's skipping so much. My nozzle doesn't seem to be clogged. I tried opening and cleaning the feeder, but no luck. Not sure what to do. I'm using ultimaker brand filament, so I don't think it's a filament problem either.

 

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Err.. well I guess it was partially clogged. It didn't seem like it when I was forcing filament through manually, but I eventually took apart the extruder assembly and used a small screwdriver to fish out pla from above. After doing that it stopped skipping completely. I've never had to do that before.

 

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OK possibly a long shot but I have been having serious underextrusion issues with my UM2. When stripping down the main head I have discovered how critical the tension is on the four main screws which clamp the main plastic body onto the aluminium section. I found that if these are tight then I get really bad under extrusion.

 

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I found a similar thing as Mark Hale to be true. The screws on the stepper/motor assembly on the back also need to just be snug (not overtightened). I was having lots of underextrusion and the motor was skipping all the time, even just manually feeding filament through from the maintenance menu. No clogs, teflon coupler was not deformed, bowden tube was fine, could not figure out why the motor could not push hard enough to extrude.

At the prompting of an Ultimaker support rep, I loosened all 4 screws on the head (the tall thumb screws) and the 4 hex wrench screws on the stepper/motor assembly on the back and retightened them only until they were just snug and no further. After adjusting the screws on the stepper motor/assembly, the clicking stopped and I have been printing fine ever since!

 

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Hi folks. Just like to add an observation I made recently regarding feeder performance. A lot of users have reported issues with blocked nozzles and/or feeder problems. I have also had these issues. However, I recently descovered these issues seem to occur as the filament reaches the end of a reel. As the material unwinds from it's reel at the back of the UM2, the radius of curvature of the filament gets greater. This can be observed by unwinding a bit of filament and watching it curl as you hold it up. As the filament gets closer to the centre of the reel, printing problems start to occur because the curvature is so great that the filament will no longer feed down the tube to the nozzle. Putting on a new reel solves the problem. However, you do waste about 10 to 20% of material.

I've noticed someone has placed their feeder on top of the nozzle. This sounds like a positive move as you are now pulling the filament instead of pushing it. This will tend to straighten the filament out and reduce friction in the feeder tube.

 

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I had that problem with the last quarter of a spool. It seems most people use one of the alternate feeders to resolve it, or you can do what I did and just wrap it around another spool that has at least half left on it, leave it for a few days to relax the tension then you should be able to print to the end.

 

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Loose filament tends to have a greater curvature which helps. I now use loose filament by choice with this holder:

https://www.youmagine.com/designs/loose-filament-holder-v3

 

That's a great design, I'm now going to use it for what I now dub "The Relaxer" for the last of my rolls that might give me issues. Printed nice and went together easily. Cheers!

 

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