PLA stuck in Bowden Tube

[Tom Gidden @gid My Robox is a Green Kickstarter Beta Portishead, UK]

A couple of times now, when ejecting filament it’s got thoroughly stuck in the Bowden Tube, with the particularly scary extruder jam noise. If I remember correctly, each time it’s been PLA, specifically the Polar White PLA that came with Robox.

In particular, it’s the section of filament that was near the head getting wedged inside the tube itself just before it enters the extruder-end fitting. It appears to be jammed in the plastic tube, rather than being restricted by the inner diameter of the fitting.

Each time it’s happened, I’ve had to strip down the entire extruder to be able to isolate the problem and then use a metal collar tube and washer to be able to get enough grip to be able to pull the filament out with enough force without risking yanking the tube forcibly out of the printer.

On measuring, the filament seems to have swollen to 2.00mm diameter for about an inch (see attached)

Any idea what causes this, and how to avoid it? @pete, ever seen this before? I’d like to document it and any proposed fix / avoidance.

My current plan is to never print with PLA again, as I hate the stuff for so many reasons. Yet occasionally, I end up giving it a go on a junk print just to use up the ~150m I have remaining. Each time, I regret it.

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[click @click My Robox is a Green Kickstarter Limited Edition]

@gid “My current plan is to never print with PLA again, as I hate the stuff for so many reasons. “

Is it only White Polar PLA you printed with or you have others, too? (CEL or third party)

[Jack @jack-strong My Robox is a Green Kickstarter Limited Edition]

i hate polar whtie pla!

[Tom Gidden @gid My Robox is a Green Kickstarter Beta Portishead, UK]

@click : only CEL Polar White PLA. I usually print in ABS, and I have some Taulman Bridge in case I’ve got a good reason for it. I’m tempted to get some of that ColorFabb XT stuff everyone’s going on about, but I bought a couple of reels of ABS from CEL not that long ago, so am holding off for now.

PLA sucks. The only real virtues for it I can tell is the fact that it doesn’t shrink (much), and the simplicity of printing, which is often a result of the shrinkage thing. Possibly the lower toxicity of fumes, too, but I’m not convinced yet.

[BHudson @bhudson I have both RoboxDual and other Robox versions Arizona, USA]

@gid I have the same problem, except mine jams in the head. I am also using Arctic white, but I have similar issues with dynamite red. I have the same solution; don’t use the stuff. I also don’t let PLA sit in the printer, it gets ejected and stored every night.

 

• This reply was modified 3 years, 1 month ago by  BHudson.

I operate two Betas and four Production Robox.
I am the US/Canada Technical Support engineer for the Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben

[Pete @pete I have both RoboxDual and other Robox versions CEL HQ Bristol UK]

I expect it is because you did not heed the advice as follows, I apologise if I am incorrect.
DO NOT TURN THE POWER OFF WHILE THE FANS ARE STILL RUNNING! (I held down shift for that sentence to add weight to it, no caps lock was used.)

The issue with powering off prematurely is that the filament path in the rear of the head becomes hot from the residual heat in the head, the heatsink will normally keep this cool but with no power to the fan the hot heatbridge will cause PLA in particular to deform.

Another possibility is that your bowden tube is too close to the bed surface. Can you tie it to the flat cable retainer using an elastic band or similar? or if you dont have that then to the fan grill?

We use polar white PLA to send out with our review units because it is so easy to print with.

For official support please visit www.cel-robox.com/support/ and create a ticket

[Tom Gidden @gid My Robox is a Green Kickstarter Beta Portishead, UK]

@pete: I definitely did not turn the power off this time: I’ve been following that advice religiously since it was given. This was also immediately after a successful print: it was printing; it completed; I hit eject; it waited to cool down to ejection temp (140?); it started ejecting; then the big scary noise happened and it was stuck.

I’ll have a go with the rubber band thing, but it doesn’t look like the tube would have been close to the bed in this case.

[Tom Gidden @gid My Robox is a Green Kickstarter Beta Portishead, UK]

@pete: I tied the tube loosely to the fan grating with an elastic band and tried PLA again… I had a model for which ABS’s lifting off the bed was problematic, so I thought I’d give PLA another go.

Once again, the damn stuff won’t eject. Tried Eject Stuck Material a few times now, and no dice. I’m going to strip it back down again, and then throw this bloody PLA away once and for all and try out this sample XT instead.

I was printing all morning in ABS, and then tied the tube up and did a textbook-perfect switch to PLA with two purges and no power-offs; one print that failed, with multiple Extruder Slip errors; and then hit Eject. So, it was definitely not a case of not following the instructions!

[David @dmullerdesign My Robox is a Blue Commercial Version]

I’ve never used PLA, only ABS. My word of warning with ABS is, don’t let the filament run out during a print as the bent bit at the very end of the reel will jam in exactly the same way.

I ordered some ColorFabb Xt too. Is there a cheat sheet for settings someplace? Hopefully, when I get my replacement replacement head I can give it a go.

Glad I sent my Polar White PLA back before opening the pack!

• This reply was modified 3 years ago by  David.

[Steve N @discosteve My Robox is a Blue Commercial Version]

I do find it bizarre that I’m near to throwing my two ABS reels in the bin as compared to my PLA reels and on here people are experiencing the direct opposite…

Steve N | Creator of things both virtual and physical

[click @click My Robox is a Green Kickstarter Limited Edition]

@discosteve Don’t throw them away! 🙂 There are people here who are more than happy to find a good home for them! 🙂

So far I printed only with polar white PLA from CEL and it, kind of, put me off PLA. It seemed too runny, warps same as ABS, extruder skips with it (unlike any other ABS I had) head seal got blown when using it (a bit tenuous connection as AM version got bumped at the same time), etc…

Definitively will give ColorFabb a go (after let @gid test it first! :))…

Until then, ABS for me.

PS Did a few prints today with yet another, new, ABS for me (printed same thing several times that failed but not because of material - some bad model geometry, some mistake in measurement, some wrong orientation, but:) and all prints were spotless printer wise…

[Tom Gidden @gid My Robox is a Green Kickstarter Beta Portishead, UK]

Looks like the PLA actually snapped off during ejection at the head, so it’s now stuck in there. I’ve filed a ticket, as I’m not happy doing a total disassembly of the head (ie. incl. the circlip) without say-so from CEL. Really annoying, as I’ve got something I want to print this weekend using the new ColorFabb XT. Seriously not using this PLA again… it’s screwed me too many times.

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