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Bowden tube pushing itself out

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I recently built an Ultimaker and was able to get prints of decent quality out of PLA. However, the bowden tube backed out of the extruder during a print. Since then, I cannot make the tube stay in the clamp. I've tried all the suggestions I could find including cutting off the end of the tube to get a clean surface and nothing seems to work. As soon as I start to extrude, the tube pushes itself out rather than feeding the filament. I have seen the bowden clamp on thingverse which I hope would solve my problem, but unfortunately I cannot print at all so I cannot make it. Is there a temporary solution which would allow me to print the bowden clamp?

Thanks

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I recently built an Ultimaker and was able to get prints of decent quality out of PLA. However, the bowden tube backed out of the extruder during a print. Since then, I cannot make the tube stay in the clamp. I've tried all the suggestions I could find including cutting off the end of the tube to get a clean surface and nothing seems to work. As soon as I start to extrude, the tube pushes itself out rather than feeding the filament. I have seen the bowden clamp on thingverse which I hope would solve my problem, but unfortunately I cannot print at all so I cannot make it. Is there a temporary solution which would allow me to print the bowden clamp?

Thanks

Try to clamp something around the Bowden Tube above the wood block and then hold this clamped item down with cable ties while the Bowden tube is pushed into it's place.

Good luck.

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How far does the small white clamp stick out above the wooden plate? The chamfered hole might be too deep, that way the small white clamp doesn't work well. Could you maybe take a picture of the chamfered bit of your wooden plate?

Example:

http://i.imgur.com/jGYAB.png

The left hole is how it should look, the right one is drilled too deep.

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The picture quality isn't the greatest but it's the best I could get right now. The chamfer looks fairly deep to me but the white clamp only sticks up enough to get the horseshoe clip on. I couldn't think of a quick fix if the chamfer is in fact too deep - any suggestions? The grey in the picture is some JB Weld that I tried but it didn't stick to the PFA. I think that the teeth in the white clamp are starting to get stripped. Is this a standard part I can buy here in the states to swap it out? What would I call that piece?

 

Try to clamp something around the Bowden Tube above the wood block and then hold this clamped item down with cable ties while the Bowden tube is pushed into it's place.

Good luck.

I apologize I don't quite understand your suggestion. Do you mean to clamp the bowden tube in temporarily or permanently? I was thinking of trying to clamp the tube with a hose clamp but couldn't find a great spot to get it in there. Plus I was worried about squeezing the tube too much and not allowing the filament to pass through easily.

Thank you for the responses and the help. I've been working on this for several days now and haven't been able to get it working. I'm starting to run out of ideas.

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Hi, I had this exact problem. What I did was take 2 wooden bbq skewers and cut the tips off them and wedge them into the wooden hole where the bowden tube connects to the top of the print head, (by the 4 metal thumb screws). This prevents the tube from pulling outwards. I then put a cable tie around them and some tape just in case. This looks awful but held out well enough for me to build this:

http://www.thingiverse.com/thing:11864

which as far as i can tell should be everyone's first print. I havent had bowden tube popping off problems since printing this.

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The picture quality isn't the greatest but it's the best I could get right now. The chamfer looks fairly deep to me but the white clamp only sticks up enough to get the horseshoe clip on. I couldn't think of a quick fix if the chamfer is in fact too deep - any suggestions? The grey in the picture is some JB Weld that I tried but it didn't stick to the PFA. I think that the teeth in the white clamp are starting to get stripped. Is this a standard part I can buy here in the states to swap it out? What would I call that piece?

I can't see the image you are linking; because it is on your computer we cannot see it. You could upload it to http://imgur.com/ and then link it here. But if as you say the horseshoe clip fits snugly then this probably will not be your problem. Do you own any calipers to measure the outer diameter of the PFA tube? It might be too small...

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Hi,

I have just finished building my ultimaker, and after printing OK for 2 days it had the same problem. I tried lots of things including printing the clamp you linked but I couldn't get past the first layer before it popped so this didn't help.

Eventually I looked in detail at the tiny pipe clip that was supplied, the cream coloured thing with 4 metal teeth that bite into the pipe. It was awful. The moulding quality was so poor that the flash of plastic around the teeth was preventing the teeth embedding into the tube atall. I found a similar one from another 6mm pipe fitting, and on comparison the teeth were much sharper and deeper and no flash. I have printed about 25m since then and not had a whisper of a problem.

I think UM if they read this need to look at the quality of these clips urgently. I suspect a lot of people are struggling with this, and it is such a simple thing!

Hope this helps

Andrew

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Hi, I had this exact problem. What I did was take 2 wooden bbq skewers and cut the tips off them and wedge them into the wooden hole where the bowden tube connects to the top of the print head, (by the 4 metal thumb screws). This prevents the tube from pulling outwards. I then put a cable tie around them and some tape just in case. This looks awful but held out well enough for me to build this:

http://www.thingiverse.com/thing:11864

which as far as i can tell should be everyone's first print. I havent had bowden tube popping off problems since printing this.

Same here ;-) I used wooden toothpicks instead. As the voltmaster said, make sure you tape them on the tube, just in case the tube pops anyways (because you don't want to go fishing for them if it happens)

JP

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The picture quality isn't the greatest but it's the best I could get right now. The chamfer looks fairly deep to me but the white clamp only sticks up enough to get the horseshoe clip on. I couldn't think of a quick fix if the chamfer is in fact too deep - any suggestions? The grey in the picture is some JB Weld that I tried but it didn't stick to the PFA. I think that the teeth in the white clamp are starting to get stripped. Is this a standard part I can buy here in the states to swap it out? What would I call that piece?

 

Try to clamp something around the Bowden Tube above the wood block and then hold this clamped item down with cable ties while the Bowden tube is pushed into it's place.

Good luck.

I apologize I don't quite understand your suggestion. Do you mean to clamp the bowden tube in temporarily or permanently?

Temporarily, so you can print the Bowden Clamp.

 

I was thinking of trying to clamp the tube with a hose clamp but couldn't find a great spot to get it in there. Plus I was worried about squeezing the tube too much and not allowing the filament to pass through easily.

Thank you for the responses and the help. I've been working on this for several days now and haven't been able to get it working. I'm starting to run out of ideas.

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WHen you are saying that the bowden tube pushes itself out what exactly do you mean? Are you saying that it is forming a plug at the top of the hot end? Or is it pushing out somewhere else?

If you are having the plug being formed at the top of the hot end between PEEK and bowden then what I would say is cutting off the end of the tube is not the answer!

The white plastic clip does not grip the tube well when you just put it on initially. It requires some force to actually bite into the tube and form indentations that result in a good hold. That force can be applied during extrusion, in which case the plug forms and the bowden tube moves up. Normally what people do at this point is take the tube out, cut it off, and restart the cycle. What you should do instead is initially make the bowden tube stick out too far, so there's a gap between aluminum plate and wooden plate. THen, when the plug forms, just take the plug out without removing the bowden tube and just adjust the aluminum plate up until its snug again. The plug should not form a second time, because the white clip has made its bite marks in the bowden tube and is now holding it securely.

If you keep cutting the bowden tube and putting un-indented tube into the clip you are not changing any condition and the plug will keep happening.

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WHen you are saying that the bowden tube pushes itself out what exactly do you mean? Are you saying that it is forming a plug at the top of the hot end? Or is it pushing out somewhere else?

 

It is pulling out of the top end of the PEEK.

Destroyer, thank you for the explanation, it makes sense now. If I understand correctly, you are saying assemble it so when it slides out, I can remove the plug, re-assemble it and the white collar should be locked much tighter. After reading your reply, I took a much closer look at the end of the Bowden tube where it has been pulling out. I slid the tube through the collar and you are in fact correct; where it ended it was grabbed much tighter. However, I am struggling to come up with a way to implement your suggestion. The bowden tube does not slowly slide out, but rather pops out very quickly. When it moves, it moves almost 3/4 of an inch or so. This is too much for me to simply allow it to slide slightly, remove the plug, re-tighten the thumb screws, and have it clear the wood and seat nicely in the PEEK.

I tried the toothpick trick and it does help quite a bit but I am still experiencing the same problem to the degree that I cannot print a part. I have ordered calipers and will measure the end of the bowden tube as soon as I receive them as it was suggested it may be too small. Would it be possible to jam the bowden tube onto the brass barb?

Thanks to everyone who has replied. I have been struggling with this every night for over a week (and am starting to get frustrated), so I truly appreciate the constant flow of suggestions to give me new things to try. From what I understand though, the magic fix for this problem is to print the bowden clamp on thingverse. While I am not ready to give up yet, if anyone is willing to print one of these for me I would gladly pay for your time, material, shipping, and a six pack (or even case) of your choice.

Thank you!

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When it moves, it moves almost 3/4 of an inch or so.

That's quite a lot! So the tube comes all the way out of the white fitting? When it happened to me the bowden moved up by approximately half a centimeter and I stopped the print immediately, took the head apart, removed the plug and readjusted the aluminum plate. After I did that I didn't have any more issues with the bowden tube popping out. Then I printed a plastic bowden clamp and am now using that.

Double check that the blue horseshoe clip is sitting all the way around the white fitting and is not off to the side or something. You do have the compression fitting installed in one of the drilled out holes in part 8B, right? I think the drilled out part helps the fitting to actually grab the bowden tube when the tube is pushed up, since the conical indentation makes the fitting compress. Maybe you could take some pictures to help with the troubleshooting a bit?

Perhaps what we (people with working printers) should do is just print out a ton of those plastic bowden clamps and send them to people who have problems. I could probably send you one.

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Hello,

I have (had?) the same problem. I can't say my bowden tube is faulty, as a brand new portion of filament goes through without special effort. Anyways i tried everything, following advices on the forum(thanks guys) and wiki.

I'm not an expert (quite the opposite), but anyways here is the result of my trials (and errors...), as well as some questions.

1) I drilled the bowden tube to 4mm inner diameter on about 3 cm hot end side

2) I drilled the bowden tube to 4.5mm inner diameter on about 0,5mm hot end side

3) I slightly drilled the brass tube to 4mm diameter (bowden tube side), in order to ease the guiding of the filament, because with the increased inner diameter, one cannot insure it will be centered in the bowden tube

4) I secured the bowden tube with toothpicks inserted in the hole on the top part of the printing carriage

5) I tied the white part with metal wire (other people used zip-ties), before putting the blue horseshoe on

6) I fixed firmly the extruder feeder to the machine by inserting small wooden pieces in the holes where it is inserted (spare plywood bits you get everywhere when you build yourr ultimaker) and printed this quick connect shim

http://www.thingiverse.com/thing:24363'>http://www.thingiverse.com/thing:24363

, because if the extruder was really moving a lot on retracts.

7) i ordered 4mm inner diameter/6mm outer diameter TEFLON (not PFA) tube on ebay (and wait for it).

8) i will print owen's clamp (

http://www.thingiverse.com/thing:11864

) and is extruder brother (

http://www.thingiverse.com/thing:17027

) as well as this adaptation for the 4mm/6mm teflon tube i ordered. (

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OK. guys. Same problem. here.....

A very important question for us was: Does the white clip go into the "8B" part with the tabs on top, or on the bottom?

What we finally did was we used a dremel with a triangular grinding-tooltip to mimick the expansion of the lasered holes in 8B, but not as deep. Not quite as deep. Only 1 or 2mm of 45 degree slope. Now the white clip simply fits in. No need for the C-clip.

The white clip has some small "knives" that cut into the bowden tube. Those might be damaged by the bowden tube pulling out. See if you can bend them back a bit before reassembly. We now have the clips with the knives at the bottom, the C-clip would go on the "inside" of the extrusion head assembly, but we don't have it.

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Hello,

I have not yet received my teflon tube with 4mm internal diameter, and not yet installed the Owen clamp, but i calibrated my step per E settings. I did this calibration using Cura, and saw that i had to set it about 10% under the theoretical value of 866 (i don't have the measured value in mind). Basically, with the theoretical value, i was extruding 110mm when i requested a 100mm extrusion.

When printing large surfaces or when using a high filling rate, this 10% adds up and i think this eventually cause the blocking, and as a further conséquence the bowden tube pops out (to much filament is fed in, and can go out fast enough, causing accumulation and pressure).

So i can't emphasize more about the necessity of calibrating correctly the step per E value. And use Cura ;-)

Since then, everything is going fine for me (but i will still switch to a 4mm ID teflon tube, is i saw somewhere that it will improve retraction efficacity, thanks to less filament friction inside the tube).

Regards,

JP

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