Questions about refilling/changing spools mid-print

Bambu Lab H2 Series Bambu Lab H2S
1

Hi,

Brand new to 3D printing, so apologies if this has already been answered.

I kicked off a large print last night that will take several days to complete. The project uses 2 colors --black and white filament. I have an AMS 2 connected to my printer with the following spools loaded: 1. white, 2. black, 3. red (not needed for the project), and 4. white.

I’m about 18 hours into my print, and the printer has been pulling filament from spools 1 (white) and 2 (black). So far so good. As far as I can tell, when spool 1 (white) runs out, the printer will automatically switch over to spool 4 (also white, same brand/type).

The single black spool (spool 2) should theoretically suffice, but I was wondering if I could remove spool 3 (red and not needed for the project) mid-print and replace it with a second black spool.

Is that possible? Would I need to pause the print to do that? Can I simply press the oval tab and manually unload the red mid-print (it’s not in use at all), drop in a second black spool, feed in the filament, and configure the printer to auto refill spool 2 (black) with the newly loaded spool 3 (also black)?

Any advice would be appreciated! Thanks.

2

No. Because the AMS will not read the filament mid print.

You will need to wait for slot 2 to run out and replace it with a new one.

You can take out the red whenever you want.

3

You can unload red fine but whatever you load back in will be “?” until the print finishes and you press re-read on the spool.

Auto-refill requires (identical) spools all loaded up before the print starts, afaik. If you worry about black running out, the only option is yes, wait for it to run out and printer will ask you to load a reel on the same AMS slot (it will not read the reel, only load it)

4

Thanks @CincinnatiDesigns and @illien ! Will plan better next time. For now I’ll replace the black spool if/when it runs out.

What happens exactly when the spool runs out mid-print? Does the print pause and prompt me to refill the AMS slot? Anything I need to look out for? Is the very end of the filament secured to the spool in any way and lock when it reaches the end? Or does it just feed in completely until there’s no more?

5

Yes. Exactly. It is that easy.

There is tape securing the filament to the spool but it should just rip off.

If your printer is networked, it will send you a notification.

6

I solution I have used is to cut the black filament in the AMS while printing. Remove the used spool and wait for the filament to be used. Printer will then ask for filament, (and pause) insert a new spool and start print again.
(Make sure you will not need more than one spool to finish the printing using black filament)

7

For those who have not experienced this or do not know what can be done or how…

If you haven’t set any ‘extra features’ for your AMS.

  1. Your print will continue until it finishes or one or more spools run out.
  2. If a spool runs out during a print, at that point, remove the empty spool and replace it with any other spool.
  3. Any replacement spool can be any other colour, manufacturer, just swap it and resume the print on the printer, Bambu Studio or Bambu Handy.
  4. Do NOT replace the spool with a different type PLA for PLA+ is fine, PLA for PETG is NOT.

If you have (or want to) set extra features, use the Bambu Studio device tab and change the AMS options.

  1. Enable Auto Refill.

This tells your print job to utilise duplicate spools in that printers AMS units.

If you have White Bambu Lab Basic PLA in AMS slot A1 and another White Bambu Lab Basic PLA in AMS slot A3 and one more White Bambu Lab Basic PLA in AMS slot B2, with slot C4 filled with an eSun PLA+ White then the following occurs.

  1. A1 will be used until it runs out.
  2. A3 will be used until it runs out.
  3. B2 will be used until it runs out.

When you begin the print, you choose if the selected white is A1, A3 or B2, whichever you select starts the order which is alphabetical and numerical.

If you choose to start with A3, the order changes to this:

  1. A3 will be used until it runs out.
  2. B2 will be used until it runs out.
  3. A1 will be used until it runs out.

You will notice the eSun white is not included as it does not match all the required elements.

Your printer can track multiple auto-refill chains.

Auto-refill does not mean all matching filaments will be used, just those needed until the print completes.

This auto-refill feature can also include a manual swap as described above. Just swap out the NEXT spool in the chain.

If you are printing A3, B2 & A1, and B2 is currently be used, you swap out A1. If you hoped A3, B2 & A1 was sufficient, yet A1 will run out, swap A3 while A1 is in use.

Important:

This feature is not without annoying bugs in Bambu Studio. It will occasionally get confused. It will sometimes think black and blue are the same as well as many other non matching properties.

You can check this by pressing the auto-refill button to see the sequences it believes are matched.

You can’t fix this, but you should be aware.

As you may be hoping to be informed your black has run out so you can manually swap it, yet nothing reaches you because the printer started using blue.

Very annoying.

8

This works great as long as auto-refill is not enabled with a matching sequence on this filament.

Because, it will just start using the next spool slot in the sequence.

9

Thanks for all the info. I think I understood all of it, but had one question about this…

If I swap A3 while A1 is in use, do I just drop a new spool into the A3 slot and manually feed the filament until the AMS detects it and pulls it in? Can it do that while printing from A1? Can it multi-task like that? I’m assuming yes, but just wanted to confirm.

I might get rid of my red spool just in case my printer gets confused and tries to pull in red once the black runs out. I checked the settings, and Auto-Refill appears to be set only for the two white spools, nothing else. But now I’m a little paranoid :sweat_smile: .

10

Yes.

Although, you push it in a bit, leave it alone, it will be pulled in when it is the next slot up, either during the print or after it completes without this being needed.

Yes.

As the you feed vs it pulls is delayed until required, nothing stops anything else.

Yes, but not technically multitasking the feeding or stuff breaks.

While technically possible, I haven’t noticed this occurring if it doesn’t show it when asked.

I wouldn’t bother, leave it in.

For this reason, you should be perfectly fine.

We should all be, they are out there!

Extra ‘feature’.

If you perform a manual swap in either scenario, NOTHING is checked for suitability. You can drop a different colour in place of the one that was there, you can add a different brand, you could, but DON’T add PETG instead of PLA.

The checks for validity ONLY occurs when the printer isn’t printing.

This is good because, you can finish a print with any other material because finishing is better than a failed long print.

This is bad because, we can accidentally throw in a different type, kill the print and potentially damage the printer.

Extra, extra thought.

Many people have requested the ability to allow any near compatible filaments to form the auto-refill chain, ideally this would have an interface to assign and order them.

This would let you use up old and nearly finished spools for a print where looks are not the point.

This would mean any PLA p, from any company would chain, but not those where the nozzle temp or type and build plate temps vary too much. So, no glass or carbon fibre variants can be mixed if you have PLA, PLA+, PLA Matte, PLA Silk (although this shouldn’t be mixed if anything is structural) and so on.

11

One other thing to be aware of is Bambu went through a number of iterations of how filament was attached to the hub.

Some of the ways that they used for spools sent to retail could cause the printer to ingest the tape. It wouldn’t let go of the filament but would let go of the hub.

No idea how much is still out there like that or how new your filament is but it is a mess if it happens. I try to never let spools run out before I can see how filament is attached and then will cut it free before the spool runs out.

YMMV

12

Some additional notes to all the comments that already have been given, at least, I didn’t see them yet.

When the filament leaves the feeder in the AMS, the AMS is unable to rewind the filament when a color swap is required. In that case it will purge the entire piece of filament that still resides in the PTFE tubes, so it can continue.

There is one very small window where it can go wrong, and that is when the filament is detached from the spool, but still in the feeder. If there is a filament swap request at that moment in time, it might retract the filament, but it can’t be rolled back onto the spool. So far I haven’t encountered this yet, but it might just push all the filament back into the AMS and cause issues with neighboring spools.

It might be possible that the AMS detects that the rewinding spool has no resistance and start purging the filament anyway. But it is a hypothetical scenario for failure.

13

If you are using a

single nozzle h2s then you don’t need to wait for the black to run out, you can just quickly swap the spool while is is doing a white section..

The will save a mid black pause or a lot of purging when the black runs out.

14

Ah interesting… it is a single nozzle H2S. Good to know. Do I just press in the oval tab and retract the black filament manually while the white is running? And then drop in a new black spool, and manually push it in?

15

I just purchased my filament last week from B&H Photo, so I think it should be relatively new?

But I was wondering about this… I haven’t finished a spool yet, so no idea how it’s attached. Guess I’ll find out soon. I figured it was taped on, and I was definitely worried the tape might get sucked into the white tube along with the filament. I’ll keep an eye out. Do other folks also cut the filament free as it reaches the end? Is that a good practice?

16

Yes- Most BL printers are generally quite happy with inactive filament spools being changed mid print. The AMS won’t reread the RFID or allow the colour to be set - so it will show up as ? - but it should carry on quite happily with using the next spool when it is ready.

You can also pause prints - I find doing this mid colour change being the best time to avoid impacts on print quality.

Cutting filament I fhink is less desirable because it will either result in filament running out in the middle of a colour, so a risk of print quality issues when the colour resumes, or lots of purging to remove the cut filament as it wont be possible to retract it back once it has been cut.

17

I only cut the filament free when it’s a slam dunk that the filament will run out. For one thing, you don’t even get access to where the filament is taped down until the spool is almost empty anyway since it has to be down to the first wraps on the hub.

Chances are good that it will be new - especially with the common colors like white and black - but unfortunately you can’t really know until the spool is getting low.

I don’t think Bambu appreciated what they did to us by putting spools in the wild with the various taping methods that didn’t work. There’s a thread here where people were posting photos of the taping methods and the damage done to extruders and AMS units. Generally minor but the cleanouts were a pain.

Worse, Bambu never supplied serial number ranges on the different taping methods. We could have been able to know ahead of time (and return the “bad” spools) but that wasn’t done.

Anyway, it’s generally not fatal to the printer or AMS to ingest tape if you do get an older spool. It’s just a mess and you lose the print.

It’s been over a year IIRC so there shouldn’t be too many left but I have a fair amount of filament on hand and do still see the bad taping jobs. I have to watch for it. But those buying filament now hopefully don’t but there may still be spools out there pushed to the back or whatever.

Just a heads-up is all.

18

Agreed for single colour prints that cutting might be worth doing if there is doubt about the filament attachment method. For multi colour prints though my preference would be just the swap the spool out while it is inactive - rather than cutting.

19

By the time the filament is getting close to running out, I can easily see the attachment method. I still cut the filament free regardless of the taping method because I just don’t trust tape. I have missed one spool running out and thankfully the tape let go properly. But I try really hard to be there when a spool is getting low. And of course I realize that’s not practical for everyone and that others just don’t care to do it.

But I’ve cut and swapped out spools even in multicolor prints. All that happens is once the AMS sees the tail, if the filament isn’t used up, it just gats purged. But I don’t cut the filament until I know it will get past the AMS filament sensor so it doesn’t try to pull it back.

20

Here’s a photo of my white filament and how it’s attached. Photo is a bit blurry, but it looks like it’s taped on.

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