Ok, how the f#!k is my bowden still popping after this mod?

[IRobertI 521]

Short and sweet. I finally decided to fix my bowden once and for all after it popped again after a few weeks of happy printing. So I put an M6 thread on it and secured it (HAH!) in place using two nuts tightened against each other with the wooden plate between. Tried a quick print, everything seemed fine. Started printing my real thing and BAM, the bloody thing pops again!? I.just.don't.understand.it.

I haven't performed an autopsy on it yet, I yanked the cable and walked out... I'll get to that tomorrow when I'm not pissed.

[Daid 306]

Well, for one, I can see that the end is not straight, allowing melted PLA to get between the PEEK and the tube, which causes a plug. Once it's plugged, at some point, it will pop. As the extruder is very strong.

(Assuming V1 hotend, with the V2 this shouldn't be a possible configuration)

[joergen 2]

Short and sweet. I finally decided to fix my bowden once and for all after it popped again after a few weeks of happy printing. So I put an M6 thread on it and secured it (HAH!) in place using two nuts tightened against each other with the wooden plate between. Tried a quick print, everything seemed fine. Started printing my real thing and BAM, the bloody thing pops again!? I.just.don't.understand.it.

Just to clarify: the threaded bowden pushed itself through the threads of the nuts upwards?

2 thoughts: M6 leaves very little material on the tube, making the remains very flimsy... i can even imagine that the bowden would simply rip off. M7 (as recommended months ago here) leaves plenty of bowden material, and would by far exceed the forces the stepper can produce.

Also, as David said, it is important to maintain a perfect seal, PLA and PEEK do not go well together, or they go too well together.

[IRobertI 521]

Right, I've calmed back down to my regular mellow self now Looking at it with calm eyes I think daid is right that the cut wasn't straight enough. I was very careful while doing it but I guess I still messed it up. I re-cut it today and fitted only a single bolt between the PEEK and wood as the top one vibrated loose as there's no tension holding it in place on the slippery tube. I did a quick ten minute print first to get the juices flowing so to speak, then I let it cool down to solidify any leaked PLA and started up a two hour print. So far so good.

I'll attempt a longer 7 hour print tomorrow (I'm not comfortable letting it run overnight, I'm paranoid about the very remote risk of catastrophic failure -> fire ).

Joergen: I was going for an M7 nut but for the life of me I couldn't find one in the fairly well stocked local hardware store so I took a shot with the M6. They might've had some "behind the counter" as I think about it now, oh well. Time will tell if it'll rip itself apart. It goes against my principles to give up but if it fails again I'll admit defeat I think so I've ordered a new hotend+bowden.

[joergen 2]

Joergen: I was going for an M7 nut but for the life of me I couldn't find one in the fairly well stocked local hardware store so I took a shot with the M6. They might've had some "behind the counter" as I think about it now, oh well. Time will tell if it'll rip itself apart. It goes against my principles to give up but if it fails again I'll admit defeat I think so I've ordered a new hotend+bowden.

I believe a 1/4in hex nut would do the trick as well, with a little bit less loss of material around the bowden. just be careful not to trim too much of the bowden, since at one point it will become too short to reach home. mcmaster will sell you replacements if you need to (if you are located in the US).

[IRobertI 521]

It seems the store I usually get random hardware from is pretty metric centric, which makes sense since I'm in Sweden. Getting "american" sizes would probably mean ordering some.

Yup, I've been very careful to keep as much as humanly possible of the bowden when I trim it. I've only had to do it a few times and I don't think I've taken away more than 2cm, if that. I also regained some length since I got rid of Owen's bowden clamp. But like I said if it fails again I'll go with the new hotend+a new bowden which should be on its way to me shortly unless the oompa loompas over at Ultimaker are slowing down for the holidays