Extruder issues

[baphi 0]

Last week I printed one big item without any problems at all. It was really just about hitting the build button in RepG and let the Ulti do the work. Workflow:

- STL-file created in SolidWorks

- STL loaded in NetFabb (christmas edition)

- created gcode within NetFabb (using 210C temp and "standard" profile)

- loaded gcode in RepG (026)

- preheated the Ulti to 210C and once the temp was reached I hit the build button

- after 4 hours of printing a good solid print was made

So far the good news... I tried to replicate the exact workflow again with a slightly changed file. The print started just fine but somewhere halfway the printhead stopped extruding. This happened twice.

After these two failures I felt it took quitte some force to push the filament (silver PLA in all three cases) through the heated printhead. I decided to disassemble the printhead once again (while still being heated).

Strangely I found no excessive PLA material above the PEEK nor in the bowden tube. But it took some really serious force to push the PLA through the end of the bowden tube, so probably there's the problem. Next step was to cut a small piece of the end of the bowden tube and after having done that, the filament could be pushed trough without any excessive force.

I reassembled the printhead and started another print job. Result:

A flawless good solid print like the first one! I hope this has solved my print issues... Maybe I'll need to install a complete new bowden tube in the future...?

So far so good. I'll keep you guys updated if this has really fixed my printing issues!

[baphi 0]

I've reached the moment to stop putting effort in trying to make the UM work... It takes me too much time (professionally) that's not worth spending.

The printer keeps giving the same issues with extruding during a large print.

So I'm throwing in the white flag...

[destroyer2012 0]

Measure your feedstock diameters! It is quite likely that the feedstock diameter increased during the print (reached a spot on the spool with thicker filament) and that's why it got stuck. In light of these issues (which I've had too!) we should start buying filament from elsewhere, with tighter tolerances. OR get a bowden tube that has slightly bigger ID OR post-process our filament to make the diameter more constant.

[baphi 0]

@destroyer2012: this issue appeared with red, white and silver PLA... I can't imagine that thickness tolerances are not right as the filament is supplied by UltiMaker themselves... But who knows... Bottomline: my company purchased the UM to be able to do checks in an earlier stage of the design process, but having this much issues isn't usable.

[ddurant 0]

After writing the above, I decided to take the printhead apart and there I found a big melted PLA in the end of the bowden tube. Not good.

What can I do to prevent this? As this doesn't seem to be an extruder problem but more a printhead problem...

I've got one of the first Ultimakers to ship and have printed for many, many hours. I've seen this problem, the PLA plug at the end of the bowden tube, only once.

My best advice, if you haven't already given up, is to never, EVER leave the machine hot. Don't even preheat until you've got the gcode loaded and the build platform ready and all that. It only takes a minute to heat up so get everything else done and ready before heating.. Once it's done printing, make sure the temperature gets set back to 0 so it cools off.

As filament moves through the system, it pulls heat out of the hot end.. If this cooling rate is less than the heating rate, the hot end ends up with an excess of heat, which moves up the system and can cause the dreaded PLA plug to form at the end of the bowden tube. The way around this is to find the (somewhat fine) line where you're just adding enough heat to the system to allow melt the filament the right amount but not so much that the excess can move up the hot end to the bowden tube.

You haven't (AFAIK) posted about the settings you're using.. If you need help getting the machine to behave properly, you should start up a new thread and post those and the probelms you're seeing.

[destroyer2012 0]

I can't imagine that thickness tolerances are not right as the filament is supplied by UltiMaker themselves...

I have two rolls of filament from ultimaker, one is white PLA which is unusable due to this problem, and another is silver PLA which varies by 0.2 mm (2.6 to 2.8 mm) in diameter. So that's a 50% success rate on their part. I guess that variation is fairly standard but if the filament happens to go above 3.0 mm (which the white does) then it gets stuck in the bowden tube and you are out of luck. Do any of your filaments go above 3.0 mm diameter and if so by how much?

[thomix 0]

I have the same problem as Baphi I think; sometimes during printing the friction of the filament in the bowden tube massively increases. I have to use pliers to push it through and afterwards printing continues, but jamming seems to occur more frequently over the course of a print, eventually stalling completely. The hot end of the bowden cable looks perfectly normal, no pluggin at all.

However, sometimes even with the hot end detached it takes a serious effort to push filament through the bowden tube itself. Did anyone else experience that?

I'm looking into getting a new extruder that can deliver more force, but I still feel like it should be possible to print with an unmodified ultimaker...

[destroyer2012 0]

However, sometimes even with the hot end detached it takes a serious effort to push filament through the bowden tube itself. Did anyone else experience that?

This is what I experienced. The problem is your plastic filament is too thick and it jams in the bowden tube. Even if you get a stronger extruder it might still strip. I had to take out my bowden tube and pull with a pipe wrench while having the bowden tube in a vise for 5-10 minutes to get the filament out. Get better (slightly smaller) filament, or measure and shave off the parts that are thicker. THat should solve your problem nicely.

[owen 19]

Just check your thumb screw isn't tightened up too much. This makes the filament oval shape and harder to get through. You can tell if a fresh piece of filament slides through easier.

[thomix 0]

However, sometimes even with the hot end detached it takes a serious effort to push filament through the bowden tube itself. Did anyone else experience that?

This is what I experienced. The problem is your plastic filament is too thick and it jams in the bowden tube. Even if you get a stronger extruder it might still strip. I had to take out my bowden tube and pull with a pipe wrench while having the bowden tube in a vise for 5-10 minutes to get the filament out. Get better (slightly smaller) filament, or measure and shave off the parts that are thicker. THat should solve your problem nicely.

I've had it with the shipped ultimaker PLA (2.89 ish) and newly bought PLA (3.00). Also, isn't the inner diameter of the bowden tube 4mm? or only 3? I do seem to have some play left.

Owen: I am often stuck in the loop of slipping - tightening - slipping - tightening - too tight. Filament deformation is definitely a problem; I hope my new extruder will be able to feed the filament with less pressure on it.

Also, is it possible that the hot end of the tube is ever so slightly deformed that this causes a problem? I am weary to cut it as it already seems shortish as is.

[owen 19]

However, sometimes even with the hot end detached it takes a serious effort to push filament through the bowden tube itself. Did anyone else experience that?

This is what I experienced. The problem is your plastic filament is too thick and it jams in the bowden tube. Even if you get a stronger extruder it might still strip. I had to take out my bowden tube and pull with a pipe wrench while having the bowden tube in a vise for 5-10 minutes to get the filament out. Get better (slightly smaller) filament, or measure and shave off the parts that are thicker. THat should solve your problem nicely.

I've had it with the shipped ultimaker PLA (2.89 ish) and newly bought PLA (3.00). Also, isn't the inner diameter of the bowden tube 4mm? or only 3? I do seem to have some play left.

Owen: I am often stuck in the loop of slipping - tightening - slipping - tightening - too tight. Filament deformation is definitely a problem; I hope my new extruder will be able to feed the filament with less pressure on it.

Also, is it possible that the hot end of the tube is ever so slightly deformed that this causes a problem? I am weary to cut it as it already seems shortish as is.

Yep, ID of the Bowden tube is well over 3mm and so is the inside of the brass tube. You should be able to push filament through easy when the nozzle is off. It sounds like your temperature could be dropping during the print, are you using Marlin firmware?

[destroyer2012 0]

Don't forget that under pressure by the extruder gear the filament will compress like a spring, meaning that it will become wider and shorter. If you filament starts out more than 3 mm and then it gets compressed it may yet get wedged in the bowden tube and then by a ratcheting action get stuck in the compressed state. When my filament got stuck I cut off like 2 inches from the hot end side and it was still stuck. And even when I (with great effort) managed to pull it an inch or so from the filament feeder side, it was still stuck. So the only conclusion is that it was stuck in the length of the tube itself, and not because the tips are compressed from the pressure fittings.

All I'm saying is, this could be happening to you.

[fightling 0]

I have the same issues. It's a real show stopper. I'm currently try to print a ballon car:

http://www.thingiverse.com/thing:16987

And It seems, it is to large to print without extrusion problems. It's such a pain!

[sammy_33 0]

I weigh the problems that we are only an erroneous design

extruder.

- The wire passes through an area too hot and has time to become soft, so 'do not push.

- The heater is too far from the point of exit of the extruded material

- Do not know about you, but the straps are too loose and you can pull more '

- I think that if they do not design changes, we are all on boat sinking

- Beginning to think seriously of throwing away so many big money

[Daid 306]

Actually, I think, if your bowden tube stays in place, and you don't get a gap between the tube and the brass. Then you won't have issues.

Now that I have two extruders, I can see the difference clear as day. One of them has insane grip on the tube, and has been printing without issues all the time.

The other has way less grip with the white clip, so the bowden tube slowly creeps up during printing. Starting with a small gap where molten PLA can creep into. Causing more friction to the filament you're pushing into the hotend. So it will still extrude, but there is more friction, giving more chance on grinding at the filament.

Now, this gap will grow and grow, until it's so large that you can have plug that's large enough so it no longer is soft because of the resident heat from the heater.

My primary (good) extruder also "plugs" in the bowden tube, but these plugs are inside the tube, and the inside of the tube is small enough so it still can be pushed into the brass to be melted then.

At my secondary (bad) extruder, everything I tried to get more force out of the extruder drive only made it worse, because you can sort of push trough the plug if it's small enough, but the bowden tube will only creep up further and further. During these problems I noticed my instinct was to get the tension screw tighter and tighter, because the filament was slipping. But that was not the source of the problems. (And if it's way to tight, then you'll get the deformation issue that destroyer2012 had)