Transparent Tube/Filament/Extruder

[mrcdesign 0]

Hello,

I had a problem that the filament in the transparent tube is pushing the transparant tube out of its place, first next to the material feeder, i was adviced to make a clip which is doing its job, but now the transparant tube is loose on the other side.

Its going out so far, that the power cable of the small circuit board is popping out all the time, disabling the thermocouple giving me 300+ degrees temperatures, instead of 215 which i wanna print with.

How do i solve this?, If UM is designed to work without the supporting clips, how can there be so much force on the filament that it pushes out the transparant tube.

 

[illuminarti 18]

There may be something about your particular Bowden tube, or how it is installed that's making it pop loose. Some people have had problems - some lots. Personally, I've never seen this happen on mine.

If the cabling to the thermocouple pops off, don't keep printing. Not only will you get bad results, but you'll quite possibly damage your print head.

Something is causing you to generate high pressures within the Bowden tube - which basically means you're pushing the filament harder and faster than it can escape out of your nozzle.

A few things to consider:

1) You might want to check how your feeder drive is assembled, and in particular what the tension is on the spring on the back of the filament clamp. It should be roughly 11mm long - the spring shouldn't be totally compressed. Part of the problem might be that you're grabbing the filament so hard that even when pressure gets quite high, it doesn't slip at the extruder end, but instead has to break something else.

2) Check your filament diameter. Is it comfortably less than 3mm throughout? When the extruder drive is open, can you slide fresh filament into the Bowden tube easily by hand, with virtually no resistance? If the filament is too thick, it will get stuck in the tube, and the extruder may keep pushing until it pulls the tube out.

3) What temperature, layer height, skin thickness, and print speed are you printing at? If you try to print too fast, the nozzle won't be able to keep up, and pressure will build up on the filament.

4) If you heat the print head, lower the bed a bit, and turn the extruder drive gear wheel by hand, what does it feel like? You should feel a little bit of push-back if you turn the edge of wheel more than one or two mm per second. But you should see continuous extrusion from the nozzle, and shouldn't feel a solid barrier. And you shouldn't be able to pop the Bowden tube off by hand.

Now that the tube has started to come loose, the ends are probably damaged, so you may want to trim the last few mm, and resecure them - perhaps with some additional sort of clamp. But it would be good to know what is causing the frequent pop-offs. I have no extra clamps on mine, and have never had it happen.

 

[mrcdesign 0]

Hello,

1- It should be fine, it worked before

2- The filament is the original shipped by Ultimaker, you helped me in another post and said it should be 2.89 Correct?

3- Temperature is 215, layer height 0,1 , skin thickness is ???, print speed is 50

I dont think im trying to print to fast, because it also happens that it just stops printing and the filament is stuck in the part above the nozzle. I have cleaned this after dissassembly, but it didnt help.

I cleaned it by heating it and also used (THF) for solving the stuck PLA. all seemed fine after.

4- Printhead should be fine. And extruder feels fine to me.

Everything has worked fine a few days ago, i printed the OWL statue on the thingiverse website, and it came out like it should, except for some under extrusion on like 2% of the whole model, so no big issues there.

I think the ussie lies with Filament getting stuck, but i dont see why, because it worked before, and its cleaned as good as i could. At the moment the filament is so stuck i cant get it out even with pliers.

 

 

[gr5 2,192]

The transparent tube is called the "bowden tube". It's a mechanical term and used to refer to those tubes on bicycles for the brakes and gear changers.

2) Just because it came from UM doesn't mean it's defective - do you have a micrometer to measure to make sure? Even better just slide some through the bowden tube.

3) .1mm layer height at 50mm is definitely nice and slow volume of PLA. The pressure build up is tiny.

Most likely it's none of these and somehow the device that holds the tube isn't working. Normally the feeder can pull 22 pounds and the bowden should stay in with that much force pushing on the filament (11 pounds each attachment point). So if you can pull with 10 pounds of force on the tube directly and it slides out then something is wrong.

See if they look damaged at all - maybe a tiny piece broke off? Some people have done different modifications. You can check thingiverse. Illuminatri's suggestion of cutting the end off sounds good.

Those clips can be found at air conditioning supply places and large plumbing supply stores (the stores for plumbers, not like home depot) - they are used commonly with water purification I believe. They cost very little.

 

[mrcdesign 0]

Hello,

When i push the filament through the bowden tube it slides smooth. Last time when it was heated near the nozzle, want i wanted to pull it out, it was very thick and i had to use all my strenght to pull it through the bowden tube. So i think its stuck in the first part, and thats a reason why it builds up all the force to push it out.

How can i be sure everything is fitting properly, it used to work well earlier, last 2 days it wont work. Normally the first 5-10 layers are good, then it starts to struggle, and no filament is coming out of the nozzle.

 

[mrcdesign 0]

The image below is the filament which was at the nozzle. It has a bend, so im wondering whats going on.

 

[illuminarti 18]

At what point in the process the bend happening? (And presumably you took this out when the Bowden tube was off the hot end - i can't imagine it would slide through the tube like this). It looks like the filament is softening well above the hot heater, and then when the tube comes off it is able to flop over to one side, putting the bend in?

Are you keeping the hot end heated, with filament in for extended periods, e.g., between prints? That can cause problems like this, by allowing heat to spread up the filament as it sits.

 

[gr5 2,192]

That bend is not normal.

Could you photograph your hot end please? From a few angles. Thanks.

 

[mrcdesign 0]

Hello,

Well i was trying to print a part of the Eifeltower from Thingiverse, and about the 30th layer or something, it got stuck.

The filament was like this when i pulled it through the bowden tube.

It could be that the filament is heating to early. I have to give it a try today, and see what happens. But im still curious on why the bowden tube is getting loose.

If i get another bend, ill photograph my machine.

Thanks in advance.

 

[mrcdesign 0]

I cut off a part of the bowden tube like you suggested earlier, and it seems fine now, ill keep an eye on it though. Thanks for the help.

 

[mrcdesign 0]

Everything looked fine for a while, but the bowden tube on the nozzle part has gone loose again, im just tempted to glue it there, but thats not wise.

The filament is not bend this time.

What do you want me to do?

 

[gr5 2,192]

What do you want me to do?

Did you read my post above?

The bowden tube should be able to handle 11 pounds of pulling force on each end. Test it. Remove the filment first or make sure the filament is loose.

Please please please please please photograph your hot end and post the picture here. to post pictures you have to start by clicking "gallery" up at the top left of this page.

 

[scottvader 0]

Hi All

My first post. Please excuse any missteps.

I have a similar problem to MrcDesign. The bowden tube seems to back-out from the hot end easily. I took it apart and noticed it was chewed up a bit where the metal teeth in the white retaining collet are supposed to grip the 1/4" tube. I cut off half an inch to put fresh material in front of the teeth. Still didn't seem to grip. I did a temporary fix so I could keep printing by cutting a couple of flaps into the bowden tube kind of like gills on a fish that would hook the collet so it couldn't back out. That worked but it won't likely last.

IMHO opinion there's something wrong with the detailing of the wood hole that the white collet fits into on the extruder end. I did a little experiment. I can't pull the bowden tube out of the stepper end where it plugs into a standard 1/4" legris style push-in fitting that includes collet and mating body. I took the grey collet out of the stepper end and placed it into the wood bore in the extruder. The bowden tube pulls out easily. I put the white collet into the push-in body on the stepper end and again I can't pull out the bowden tube.

I think my permanent fix is going to be to put in a standard 1/4" legris push-in fitting on the extruder end as well.

best regards

Scott Vader

 

[mrcdesign 0]

Down below the requested pictures of my extruder.

The nozzle and aluminum block are a bit dirty, thats because i tried using the "newer" soft PLA, and i think it has some sort of oil liquid in it to keep it soft, which was getting on the head after the print was messed up. Dont know how to get it off.

I also know the head is not mounted like the tutorial, but this way it has more space between the nozzle/aluminum block and the custom fan mount.

 

 

[illuminarti 18]

The main thing I see is that the brass tube should be screwed all the way into the brown PEEK part, so that the circular flange is in contact with the PEEK. Having it sticking out like this means that the top of the brass tube isn't mating up to the teflon part, leaving a wider part between teflon and brass tube, where soft/molten plastic can get ooze out, and then solidify, causing plugs. The plugs stop the filament moving, and then the feeder keeps trying to jam more and more filament into the bowden, until something gives. In this case your Bowden tube pops off.

The instructions are written to reflect the design, and the design reflects the need to make the hot end work. Follow the instructions!! :-)

 

[mrcdesign 0]

Hello.

Well now you mention it, how did you screw the brass tube in the brown PEEK part?

I have turned the aluminum block 180 degrees so there is more space between the block and the Fan mount, is that also a problem?, Else there is only 1 mm of space, and then it starts to melt. Now there is about 3-5 mm.

 

[illuminarti 18]

I don't think that the orientation of the heating block matters particularly, although usually the thermocouple and heater are threaded through the block from the same side (which usually ends up being the back of the printer), and the block is in the front right opening, aligned front to back, and the fan is mounted on the left. Most thingiverse fan designs for instance assume that orientation to get the shroud away from the block, and the output as close to the nozzle as possible, without blowing directly onto the nozzle tip. You also need to make sure that any fan mount that you use is designed for the V2 hot end (which you have).

But the main thing that you need to fix is to screw the brass tube in properly. You're probably going to have to do it while it's hot, as there's probably PLA stuck in the threading above the end of the brass now. You probably need to disassemble it, and inspect it to see what you need to do. You could soften the PLA enough to work with by heating the tube and PEEK in boiling water, or in an oven set to a low temp. You might possibly need to use a tap to cut a clean thread in the top part of the peek now... at the very least you need to be careful you don't apply too much force to the brass tube - they can break fairly easily. I've never had to deal with any of this myself, so I don't have any particular insights to share, or experience, but I think it should work.

Depending on how long you've had the printer, you might want to open a ticket with UM support as well. There were several cases in the last few months of PEEK parts having missing or imperfect threading - maybe that was why you weren't able to screw the brass tube in all the way?

 

[mrcdesign 0]

Depending on how long you've had the printer, you might want to open a ticket with UM support as well. There were several cases in the last few months of PEEK parts having missing or imperfect threading - maybe that was why you weren't able to screw the brass tube in all the way?

I think this is the case, i had to use oil and 2 pliers, and scared of breaking the brown PEEK parts, well you know the feeling when something is not fitting properly. I will disassemble it and try to get it all the way in, and if i break it, i have to order a new one/or, send a ticket to UM.

Thanks for the help. I hope this can fix the issue.

Edit: I have the printer approximately 2 months now

 

[mrcdesign 0]

I have disassembled the extruder, and indeed there was a little blob in the brown PEEK part, with more oil and 2 pliers its fitting properly now, so i hope this helps, ill assemble my printer again, ill let you know if it helped. Thanks again.

 

[scottvader 0]

I hope you'll tell me if this is bad form to extend this thread, I don't know the etiquette.

My V2 hot end doesn't have the issue with the PEEK bushing that MrcDesign experienced. The flange on the brass pipe is tight to the PEEK bushing and the top of the brass pipe is tight to the teflon insulator.

I did review the v4 extruder assembly instructions and now realize that I have a v3 extruder. I received my Ultimaker in March and it looks like v4 with the black injection molded strain relief came out in April. I'm a bit skeptical of whether that will ultimately solve the issue. The legris style push-in fitting is designed to take positive outward pull from internal air pressure in a pneumatic system. The new versions of Cura use retraction which will cause a push-in force on the bowden tube. That's what you do to release the tube from a push-in fitting.

Still I'd like to try to upgrade my machine to a v4 extruder.

Is it possible to get that black injection molded wing shaped strain relief part?

regards

Scott Vader

 

[gr5 2,192]

with more oil and 2 pliers its fitting properly now,

 

Yikes. I would have bought a tap. I hope you didn't break the brass as it is delicate. I guess you would have mentioned it.

Do you also have a problem where much less than 10 pounds force can pull out the bowden tube?

 

[illuminarti 18]

Hey, Scott. No problem, feel free to contribute here. :-)

Fwiw, the coupling on the extruder gear end of the Bowden always seems to work really well for me. (But then so does the other end, so maybe this doesn't really help you).

As far as I can tell, the back and forth motion of retraction doesn't cause the tube to uncouple, since that requires the fitting to be pushed in at the same time that the tube is moving out. When the Bowden moves in the course of printing, its always moving the fitting in the same direction that it is moving.

That said, the slack in the Bowden's coupling does cause some problems in terms of the efficiency of retraction, so lots of people tend to put various clips to take out the slack.

 

[mrcdesign 0]

Hello,

The brown peek part is still intact, and i did use a tap to make it just that little bit bigger, else it was just impossible to get it all the way in. Now i could see the brass part from the other side, before i could not. (for as far as i remember)

I made a small print and it looked fine, because i didnt have time. I could do a bigger print today.

I dont know about the pulling force Gr5, didnt test that. How do i do that? Just to make sure thats fine.

And Illuminart i have such a clip on the material feeder, but not on the extruder, maybe i have to put one there aswell, if it fits.