Bowden Tube Popping Out

[analog_banana]

I nearly managed a useable print today!
but my machine is now down due to the Bowden tube constantly popping off at the extruder end.

I don't think the nozzle is jammed - I can push filament through manually.
I have been trying the systerm at higher temperatures to see if it's jamming,
but i'm well within the "non skipping" zone of extrusion.

Normally if I'm under temperature my extruder skips, but not now.
All that happens is the Bowden tube pops out.

I have trimmed 10mm off the bowden tube where it may have become worn in the compression fitting,
but the results are just the same.

Perhaps the compression fitting itself is worn out?

[geneb]

It's likely the fitting has failed. Each time the extruder skips, it is going to flex those tiny little metal teeth inside the push fit connector. Do that enough and they'll fail due to fatigue. I destroyed a couple of those in my pitot & carabiner-equipped climb up the learning curve, so it's really not surprising that it happened. The interesting thing is that not everyone hits this particular bump. I think I've seen about 10-15 mentions of the push fit connector failing. The number of connect/disconnect cycles may be relevant as well.

g.

[analog_banana]

Seems like that's the problem - There's a temptation to use some duct tape to hold things together while I wait for a replacement.

Speaking to John at seemecnc, I think he told me there's a difference between "old" rostock max compression fittings and "new" rostock max compression fittings from when they updated the hotend design.

They all look the same to me, but If anyone know more about this I'm all ears.
I'm trying to find out a part number now as I think it's something I could buy locally.

[analog_banana]

Btw - when you say Pitot and carabiner, is that a metaphor for your ascent of the reprap tree of knowledge?
Or do you actually use some kind of carabiner contraption as strain releif on the bowden tube?

[Batteau62]

I don't use a piton and carabiner...I use a retractable badge clip, large fishing swivel and carabiner

The bowden isn't actually in the carabiner, just the wiring harness.

[geneb]

Piton! *facepalms*

The learning curve for 3D printing is more of an "L" shape than a curve. You slam face-first into the base of the wall, look up and flip a coin to see if you're going to pick something simpler. Say particle physics, quantum mechanics, or women.

g.

[analog_banana]

Hope this is compatible with my 2013 rostock max.
http://seemecnc.com/products/4mm-quick- ... tc-fitting" onclick="window.open(this.href);return false;

For now the bowden tube is attached with epoxy. Hope it's srtong enough for more testing.
If anyone knows of a european seller for these things let me know

[dpmacri]

Hope this is compatible with my 2013 rostock max.
http://seemecnc.com/products/4mm-quick- ... tc-fitting" onclick="window.open(this.href);return false;

For now the bowden tube is attached with epoxy. Hope it's srtong enough for more testing.
If anyone knows of a european seller for these things let me know

I can't guarantee they'll work, but these: http://www.amazon.co.uk/Tube-Pneumatic- ... nnector+M5 look very similar to what I bought from the U.S. Amazon at this link: http://www.amazon.com/gp/product/B0065R ... UTF8&psc=1.

[analog_banana]

Thanks! Bought..
It's all about knowing the right search term - I could not find them myself.
7 to 23 days shipping so it's probably coming from China.

[neurascenic]

the epoxy probably won't work for long. the PTFE is really tough to get anything to stick to. I think it is what they commonly call Teflon®
(too lazy to google it right now)

There might be a special epoxy that works with it. I have used special epoxies before that bond to HDPE, another plastic that is hard to bond to.

The part you ordered, is probably the better route, as you would have to buy a much larger quantity of the epoxy than you would need to repair that.

Good luck!

[dpmacri]

FYI, I was also able to temporarily repair mine by shaving a little off the end of the tube and force threading a nut (I think it was a 6-32, but I'm not sure) onto it (I didn't have a tap-die set, if you do, do that ). Then I kapton taped that into the broken fitting.

[Eaglezsoar]

FYI, I was also able to temporarily repair mine by shaving a little off the end of the tube and force threading a nut (I think it was a 6-32, but I'm not sure) onto it (I didn't have a tap-die set, if you do, do that ). Then I kapton taped that into the broken fitting.

That is a great idea! I'll have to remember that.

[analog_banana]

the epoxy... does not work.
This machine is busted once again.

I'll be back in a week to a month month depending on how long it takes to get compression fittings.

[Batteau62]

I posted the following in this thread: http://forum.seemecnc.com/viewtopic.php ... tie#p27045" onclick="window.open(this.href);return false;

"I haven't experienced this yet(knock on wood) but I have a theory for a quick fix. Let me see if I can explain...basically put your bowden tube inside another tube and hose clamp/zip tie at both ends just below or on the compression fitting. The fix tube would have to be just large enough ID to allow the fittings in, a stretch fit would be optimal. The length of the fix tube should not allow the original tube enough "wiggle" to come out of the fitting. Might work? If you can source the fix tube? At least long enough to get a printing fix and or replacement part "

I still think it will work. All you need is a length of tube aprox. 1/2" ID and 2 hose clamps. As long as you get the length right, it shouldn't allow your bowden to come out of the compression fittings.

[Eaglezsoar]

dpmacri and Batteau62 have given you a couple of great ideas, one of them should work for you, at least temporarily, until you get your order from the States.
Please give one of them a try until the parts arrive.

[JolietDelta]

I'm using Festo QSM-M5-4 fittings (P/N: 153304). These are probably not the cheapest, but the quality is outstanding. You can get them in the UK and U.S.

~Jens

[analog_banana]

I tried various hacks to stay printing, but I was getting all kinds of random filament outages.
The machine would just stop extruding.
I suspect this was a result of intermittent constriction of the tube, caused by whatever mechanical pressure was exerted by the quick fixes I tried.

So I decided that as I am still troubleshooting, there's no way I can troubleshoot with multiple weak points in the system - it's a waste of time.

I may have found some uk suppliers for the part that failed, but a lot of places wanted me to have a business account to buy, and I was orders of magnitude below the minimum spend!
I should have the part today or tomorrow from a place I found that sells to the public, but only if you telephone them : http://www.indanc.com" onclick="window.open(this.href);return false;

Thanks for the part no. Joliet. I'll try the festo part if the next one is a dud.

[analog_banana]

Got my new ptc connecters - all good - end of thread!

[cope413]

If you'd like to extend the life of those new fixtures, I would suggest printing these out and using them...

http://forum.seemecnc.com/viewtopic.php?f=54&t=4315