AMS-HT and H2 Series Left Side Error - HELP

Bambu Lab H2 Series
1

Here’s a puzzler.

I have 2 AMS 2 Pro’s and 2 AMS-HT’s hooked up to a BL H2D.
Left side - AMS2Pro/AMS-HT. Right side - AMS2Pro/AMS-HT.

For some reason, the Left side AMS-HT consistently gets the too much (I forget the word) resistance?

I’ve done the trouble shooting thing.

I installed (somewhere around) five different lengths of the PTFE… all errored. I adjusted the placement of the unit in conjunction with the printer… all errored. I’ve swapped AMS-HT units and it continues to fail. I’ve even replaced the unit with a new AMS-HT as a “jic”. Also replaced the hub for that side. Still errored out.

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No matter what AMS-HT I put in that place on the Left side (and no matter if the PTFE tube is long, short, medium, etc), it gets this error.

I connected both AMS-HT units to the Right side and they print fine.

What am I doing wrong here?

Is there an issue with the Left side that it will not utilize an AMS-HT for some reason?

2

Got similar issue on my H2C right nozzle. A week ago, when a spool run out, the last 2 cm of the filament misshaped and clogged, I had to remove <the part I don’t know exact name> to clean it up. After that, the right nozzle has a 50% success rate of sending filament in. AMS pushes it all they way up to the nozzle, however the hot end cannot clamp the filament.

I guess there is some tiny misalignment after fixing the clog, to solve that, I need to cut the filament head with an A shape, then it works fine. I do see on wear and tear on <the part I don’t know exact name>, only after 300 hrs of print time.

I have been using the stock PTFE tube to be connect AMS, which is too long based on BBL’s 600mm recommendation. I will cut it shorter to see if it improves, will also try to reinstall the PTFE tube on the right nozzle.

I also see many people complain that: if PTFE tube touches the top glass, that marginally extra resistant can trigger this error. This looks to be a common issue, there is a thing on MW to lift the top glass of P2S by 1 inch. But for me the error persist even without the top glass.

3

Well, it’s not really the issue I’m having. The AMS2Pro works fine on the Left and Right. The AMS-HT works fine on the Right. The only thing that triggers and error is ONLY the AMS-HT on the Left side. The same unit works on the Right just fine. And the AMS2Pro works fine on the Left and Right. It’s bizarre. I narrowed it down to just that one model on that one side. The buffer didn’t fix it. The different sized tubes didn’t fix it. Heck, several AMS-HT units swapped out didn’t fix it. It’s like that side simply will not allow ANY AMS-HT unit to be involved in a print without throwing out that resistance error. So freekin weird.

4

Is it the same filament on the left side each time you change? Is it possible the spool for that filament is bent or damaged? Cardboard? If you haven’t tried, try a known good spool on that left side with your HT. I had a similar issue and thought I tried everything until I realized I had a bent plastic spool causing the resistance. It wasn’t an obvious bend either. Just an idea, not saying its the solution but worth looking at if you haven’t.

5

Of course. Filament was ruled out first. I’ve utilized only BL filament during troubleshooting. Isolate the variable. But during ownership, I’ve run BL PLA (Basic, Matte, Silk, Translucent, Metal, Marble, and Sparkle) and PETG-HF through it. It’s errored on any and all. It’s this bizarre case where that side flat out won’t accept any AMS-HT. And for clarity, I don’t use any filament on cardboard spools. Only BL on that particular printer. My A1Mini gets Sunlu TPU at times. The rest is BL filament. That will change in time, but that’s where I am today.

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6

Is it just throwing the warning or is it refusing to print backing out and feeding a few times before giving up? In my experience the HT is a little more sensitive to anything adding resistance in the path, including the buffer. Of course mine are pretty long runs but they dont refuse to work, just once in a while they throw that message. The 4 in 1s are a common area where a tube can get a little cockeyed and add resistance or even cause a little catch which can either abort the feed or complain once its extruding. Im asking because you have 4 of them connected so figure you’re using the splitters.

7

It actually prints fine. Never had an issue with printing. But it throws an error each and every time the AMS-HT is utilized on that side. And yes, I have a buffer on each side. And yes, I swapped out the buffer for a new one JIC. Same results. I’ve swapped out literally everything outside of the printer. The filament, AMS-HT, PTFE tube leading out, the buffer, and PTFE tube leading into the printer. All of it. Same results. For what it’s worth, I’ve run three different AMS-HT units through these tests - all the same results. I’ve cut and adjusted PTFE tubes multiple times. This is really got me stumped.

I’m at the point where I just run both AMS-HT units through the Right side along with the AMS2Pro and leave the single AMS2Pro by itself on the Left side. It’ll play heck with the symmetry of the setup (and mess with my mind), but at least I won’t get the error.

I’m gonna let the members here take a stab at this before I bring in BL. I’d like to solve this on my own without having to deal with Tech Support.

8

You keep saying buffer, but do you mean the 4 in 1 adapter? H2D buffer is inside, I just replaced mine due to a self inflicted wound on it removing the tube and got a little too aggressive when holding the spring and it slipped then I ripped the metal teeth out. Adult beverages and PTFE fittings do not mix.

If you do have the 4 in 1 try without it and only the HT connected to the port on the back. Since you’re getting this will all of your HTs, you could still have something going on from port in back to the print head.

EDIT: I take the stiffest filament I have and feed it slowly and manually through the source to the head and can usually tell where sudden resistance comes in. Resolving that usually makes the HTs happy until I move something.

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9

Excellent idea. I had not attempted this. I ran the AMS-HT directly to the printer bypassing the 4n1. It printed flawlessly.

So we had a success there.

When I connected it back to the 4n1, it errored out.

So I focused on the PTFE from the 4n1 to the printer.

I ran a stiff filament through the PTFE and found that the 4n1 is where it got rough. I swapped it from one of the four holes to a different hole and it got smoother. However, when it tried to exit the 4n1 to head to the printer, it definitely got stiffer. There’s a place at the exit where it almost “clicks” as it exits. I pulled the tube out and trimmed it several times trying to alleviate the “click” - no joy. It won’t allow for a smooth exit. Neither will the other 4n1. And oddly enough, my spare 4n1 does the same thing. No idea what’s going on with that, but it’s definitely a rough patch for resistance. All three of my 4n1’s bear this out.

In order to alleviate any sort of resistance, I unmounted the twin 4n1’s from the computer (BL printed mount) and let them hang freely. That allowed the PTFE’s to relax as much as possible.

I swapped out the PTFE from the 4n1 to the printer (I’ve done this several times, but I realize just how finicky these can be) and it failed. I put a longer PTFE on there and tested. When it failed, I trimmed a bit off and repeated the test. I did this each time it failed. Eventually, I was able to load the filament ok without error.

With the filament loaded, I attempted a print - no joy.

I mounted the 4n1’s back to the printer and focused on the PTFE’s again. I did some microfine snips to the end of the PTFE where it leaves the 4n1 and seated it. I loaded the filament and attempted a print - success.

I unloaded the filament to set the machine to idle (all filament unloaded and the machine ready for action).
With the filaments in the AMS-HT’s and the printer idle, I ran three more test prints on both the right side and the left side utilizing only the AMS-HT’s - success.

My takeaway - the 4n1’s need some work. There’s a place at the top where the filament exits the unit enroute the printer where it seems to somewhat hang-up the flow. Not sure what’s going on in there, but it’s definitely happening in all three of my 4n1’s at multiple angles with multiple lengths of PTFE. I can fine-tune the PTFE, but it doesn’t alleviate the “grab” there. Also, not all of the ports (the four entry ports at the bottom of the 4n1) are created equal. One of the ports flat out would not allow the filament to pass through smoothly. Three did. One of the other 4n1’s suffered from the same bad port. The third seemed to be ok.
These 4n1’s need more attention.

Thank you so much for the assistance. I genuinely could not have gotten this far without the help.

And user_2463535618 (if that’s your real name), outstanding idea on how to proceed.

Understand, this states that there is a solution. But the truth is, the only solution would be for BL to refine the design on these 4n1’s. Or perhaps refine the manufacturing quality control? Anyway, that’s the issue at play.

10

Haha, no thats just the default auto name and I just haven’t gotten around to asking for it to be changed.

This is something lots struggle with which is why so many alternative splitters are in makerworld. Other things will cause problems as well, the fixed radius clips, tube organizers, etc all look great but they keep the tubes from flexing as needed with curves in the filament. This is why I like to use a stiff fiber reinforced filament and feed it from where the AMS tube starts to the print head looking for areas that have too sharp of a bend or something keeping the tube from flexing.

Rolling up a water hose, turning on those flexible hoses, a fire hose filling up - thats what Im talking about. Its water, but a hose will still move around if its not uncurled right.

I suspect many ignore the warnings and it puts more load on the motor and causes premature wear. We after all as a species will argue with a street sign and go the wrong way blaming everyone else for getting lost.

11

So I printed and built a couple of the Smoothy filament guide things.

Man oh man, what a difference.

It’s all roses and kittens now.

I sincerely thank you for the guidance.

Problem officially solved.

Cool place.

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