A1 Flushing system design issue?

Hello I am an early owner of a A1 with AMS lite.
These last days, I met more and more issue ejecting the filament before and after changing color.
Sometimes the ejection lands in the plate causing print failure (movement, bad fusion), sometimes the poop is blocked within the ejection system. It has a very thin blade moved by the block head and a spring system. It is so fast that the poop can literally fly in the room.
Any clue to preserve the prints and optimise the ejection please ?

Update : I printed this Bambu Lab A1 mini purge wiper fix (temporary fix till next firmware version) by zemistr - MakerWorld
the blade is now really at right of the system and it is able to eject properly the purge.


I’m having the same issue. Almost every multi-color print has had purge blobs that fail to eject from the nozzle and end up colliding with the print object or stuck to the prime tower. The collisions usually disconnect the print object from the build plate and ruin the print.

I have three X1Cs and this A1. I don’t print anything on the A1 if I can’t check it frequently through the entire print time because I’ve waisted too much filament on continuing to print objects after they were ruined by an errant purge blob.



A new firmware version has been release yesterday.

Maybe this optimization will help

  1. Optimized tool head flushing filament position

You can also check this troubleshooting page on the official wiki :

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I will test it :slight_smile: many thanks

Has somebody tested this new firmware ?
Does it correct the flushing issue ?

Flushing is better but I still need the plastic fix to push completely the blade. The fix proposed by Bambu didn’t work (tightening more the flush system and make a small angle) or didn’t change the distance from the blade.

clean the nozzle, do a cold pull of the filament and use a wire brush on the nozzle at 180-220 deg with the sock off, there is absolutely no reason anything should collect on the nozzle tip and not eject to the left cleanly, if you watch the purge does the filament list to one side instead of straight down? one other thing I have had to use with certain filaments is ptfe lube on the very tip of the nozzle due to the factory coating wearing out, they seem to fixed this so it’s my out of left field fix for anomaly’s

I have not received my A1 yet but after looking carefully at Bambu’s fix, I agree it cannot help much.
From the videos I watched, I think the problem is mostly mechanical.
The head of the printer, in its today configuration, does not / cannot push the trigger of the ejector fully in its position to the left and therefore the blade does not come to its correct right position.
And may be the movement is also too fast.
The plastic fix seems effective, like you said. Bambu should integrate this in a future redesign of the trigger with a wider head.

I must have made a mistake when loading in a new color and now the filament is setting in the tubes. Any video content on how to do a cold pull for the A1 mini?

There are video’s on it what filament did you last put in it, so I can tell you what will chemically bond so it’s sucessful?

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I’m using only Bambu PLA filament. I was trying to unload the basic white filament with a red color. I was doing the loading and unloading process and now the white it stuck in the tubing.

This is my first 3D printer and it’s been operational until I tried to switch out filaments. I am somewhat techy savvy and can probably following instructions on how to address it but can’t seem to find A1 specific instructions

Since it’s pla you can use another PLA to bond without issue I would choose a lighter color if you have one, and since I think they still aren’t shipping the A1 w/o the AMS lite yet, you’ll need to take off the 4 to 1 PTFE holder so you can hand feed the filament into the extruder @ 240C until you see a full color change, and stop the nozzle from heating watch the screen as the temp drops and when it hits 90-80 C thats when you give it a pretty serious tug, repeat this until its clear, you should see the filament path clearly in the pull if it looks deformed wait a few degrees more for the next pull, the same videos for the Prusa Mini work for the A1 but what I’ve explained is basically for any machine on the market too

+++please trim the cold pull off before re inserting the filament+++ didn’t do that once and it was really bad

Thanks for taking the time to detail this out! I truly appreciate it!!!

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You can’t tug the filament out if it’s gone through the extruder, you need to manually reverse the gears using the menu (and manually draw it in through the gears too)

I guess I got lucky. Mine is fully updated and I just finished a 2 day print that used all 4 colors each layer. All the little poops went through the shoot into the box under the table. My machine is 100% stock.

I am running the purge calculation at 0.4 and the prime tower at 30 with flush to infill on and, 3 of the objects where purge to object.

It’s kinda frustrating that with the most recent code, and the mini purge wiper fix in place the A1 still occassionaly drags the poop onto the build plate where it can get onto the print. Seems the metal catch box thingy should be a little deeper so the purge doesn’t pile up enough to touch the nozzle.

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right ! I have another suggestion : a better slope towards a poop reservoir and the blade with a steeper angle will reduce the chance to have a poop in the print.

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i had this same problem, but only with the .2 nozzle, .4 was working fine, but with .2 the poop would get to tall and glob up almost everytime, printing the plastic pusher and attaching it seems to have helped so far.