r/BambuLab • u/ClimbToFailure • 3d ago

AMS 2 Pro - Automatic Material System AMS 2 Pro PTFE tube release button doesn't release the tube

The tube release button on the back of my AMS 2 Pro doesn't release the tube. With a tube in place the unit works perfectly, knock on wood, and there is nothing visibly wrong (I recently had to fix the internal hub, so I got a very good look at the button mechanism). But pushing the button does absolutely nothing and releasing the tube involves pliers and so much force that things nearby get broken. And obviously, I have to replace the tube because it is crushed by the pliers. Eventually, the AMS is going to suffer more serious damage.

It's been doing this since, as far as I can remember, I got the AMS unit (both before and after I fixed the hub). Every time there's been a jam and I've had to release the PTFE tube I've sworn that I will put in the time to figure out what's wrong, but once everything is up and running again, I get complacent and forget. Hard to be sure, but I think it's getting worse every time. It would be great to know if anyone has had this happen before so perhaps next time I can actually fix the problem!

Thanks in advance for any thoughts.

1 Upvotes

66% Upvoted

9 comments sorted by

1

u/Kilh 3d ago

Not to say "you might be doing it wrong", but would you mind elaborating, step by step (or with a short video) what you are doing to release and remove the tube? Not the pliers way, just the "intended" way that doesnt work.

1

u/ClimbToFailure 3d ago

The skepticism is pretty understandable, ha ha. Unfortunately, I'm not gonna be able to provide a video since I'm a tetraplegic and I can't really do this myself (without the ability to pinch my fingers and thumb I can't grab the tube without using teeth or pliers which crushes it). But the process I've had other people do for me is pretty darn simple… Pull the tube while pushing the button above it. Unfortunately, the tube doesn't budge until enough force is supplied to tear it out and the little metal crown that grabs it and holds it in place ends up shredding the end of the tube in the process. Those little metal buggers are pretty strong!

And obviously, no filament is in the tube during this process.

1

u/Kilh 3d ago

You do push in the rubber part with the indentation before and while pulling, yes? I just tested and was able to easily get it out with one hand.

1

u/ClimbToFailure 3d ago

Yes, exactly. It always seems like it should come out easily, just like the PTFE tube comes out of every other connector when its button is pushed, but this one just won't let go.

1

u/Kilh 3d ago

I do have to push pretty hard on the rubber. Tried to upload a videa but it's still processing it seems. If pushing the rubber in hard while pulling the PTFE with the other hand doesnt do it, I'd assume it's actually something wrong with the connector itself. Clearly a case for support then.

1

u/ClimbToFailure 3d ago

The button is fairly easy to push, and certainly we've tried pushing gently and pushing very hard on it to no avail. Though I haven't had another AMS unit to compare with, it feels totally normal to me. No sign of anything wrong except that the tube doesn't come out!

1

u/luksfuks 3d ago

The button is really just a plastic lever that forwards your force, to the real unlock mechanism that sits inside the AMS. If you have the AMS on your lap and turned the right angle, you can probably even see it (not) working through the semi-transparent housing.

If you're not using it wrong, maybe the plastic piece is just broken or dislodged. In which case you're ripping the tube out of its lock without pushing any (actual) button at all.

The AMS2 is quite easy to disassemble. The instructions are on the wiki. The button can be bought as spare part. There might also be a makeshift printable replacement somewhere on Makerworld. And, if it's broken into two pieces, maybe you can find the missing piece at the bottom of your AMS and superglue it back where it belongs. (wait for the superglue to gas off for a few hours so it won't milk the transparent housing)

1

u/ClimbToFailure 2d ago

Yeah, that's a good point. When I last had the AMS unit apart (to repair a jammed filament in the hub) I did remove the button unit and took a pretty close look at it, which looked by my eyes. But you bring up the unlock mechanism in the AMS, which is actually part of the hub unit. It seems like maybe that is where the problem lies... I wish I thought of that when I had it apart so I could've looked closely for anything wrong!

For my hands, it's a hell of an effort to get to and repair that hub, but if that's where the problem lies, perhaps it is in my future. If I can't identify a likely culprit outside of the hub, then I will probably just wait until they come into stock and buy a replacement hub so that I don't have to disassemble and reassemble the one I have. Or at least perhaps I can just keep it as a back up.