Waste chute blocked on a long multicolour print — no warning from the printer

[sandopolo]

Hi! I’m still fairly new to this. Picked up the P2S not long ago and only added the AMS about a week ago, so this was one of my first real multicolour jobs and I clearly didn’t know what I was getting into.

Sixteen hour print with a lot of filament changes. I was using a waste bin I printed myself, medium size, which seemed reasonable at the time. At some point it filled up and the purges started backing into the chute rather than dropping clear. The printer carried on regardless. I noticed at around fourteen hours and by then the print was gone.

The bin being undersized is my own fault, I just had no sense of how much waste a job with that many swaps produces.

What I’d like to understand is why nothing warns you. The slicer knows the number of tool changes before the job starts, and the purge volume per change must be a known figure, so the total is predictable at slice time. Nothing seems to surface it. And during the print, a blocked chute presumably changes something measurable, back pressure if nothing else, but the printer just kept purging into a hole that was already full.

Two questions for people who do long multicolour prints regularly.

What’s your actual setup? Bigger bin, chute extension, no container at all, pausing to empty it, or arranging the colours so there are fewer changes? If you use one of the MakerWorld extensions, does it genuinely solve the problem or does it just move the pile?

And is there a waste estimate or warning somewhere that I’ve simply missed, either in Studio or on the printer? Even a predicted volume at slice time would have saved me here. I’ve had a look and found nothing, but I’m new enough that I could easily be looking in the wrong place.

I’ll add photos tomorrow. Mostly I want to know whether this is something everyone works around quietly, or whether I’ve made an obvious begginer mistake.

[RetroSharky]

@sandopolo

And is there a waste estimate or warning somewhere that I’ve simply missed, either in Studio or on the printer?

In Bambu Studio, after slicing in the upper right corner:

---

There are also various information panels from which you can choose:

[lkraus]

@sandopolo

What I’d like to understand is why nothing warns you. The slicer knows the number of tool changes before the job starts, and the purge volume per change must be a known figure, so the total is predictable at slice time. Nothing seems to surface it. And during the print, a blocked chute presumably changes something measurable, back pressure if nothing else, but the printer just kept purging into a hole that was already full.

The printer “assumes” it can fill the whole universe with waste; the restrictions are imposed by the user. There is no “back pressure” or waste sensor. It would be difficult to estimate waste volume because the waste shape is random, and so is the manner in which it piles up, especially with user-created bins and chutes of unknown size or shape.

I printed one poop chute and then decided it had been a waste of filament. Like most, it was too small, and too restrictive.

Just find an empty box in the trash. Pick one bigger than you think is necessary, replace it with a smaller one later if you think you can. Not too tall, so that if it overflows, the waste can spill out rather than back up in the chute.

[sandopolo]

Thank you, that’s exactly what I was missing. Switching Color Scheme to Filament gives the Purged column, and there it is.

The number is quite something. On your screenshot that’s 204 g of purge across 474 changes, more than the model itself weighs. I’d sliced mine without ever opening that panel, so I had no idea the waste was anywhere near that.

I asked the same thing on the subreddit and the replies were useful in a way I didn’t expect. Nobody mentioned the Purged column at all. One person said they’d printed a bin sized to hold more than any single print could produce, which is the sensible workaround, but it’s an estimate rather than a number, and it only exists because they’d already been burned. If that figure were visible where people actually look, nobody would have to guess.

The other reply was more interesting for my case: their P2S clogs at the rear exit fairly regularly and they reach back and clear it by hand, regardless of how full the bin is. So volume might not even have been my problem. The bin filling up may have been what I noticed rather than what started it.

Which is the part I’m still stuck on. The purge total is known at slice time, but nothing connects it to what the container holds, and nothing watches the chute during the print. A blocked exit presumably shows up somewhere measurable, back pressure or a failed purge, and on a two day job the only thing standing between that and a ruined print is someone walking over to look.

The Purged column solves the planning half though, and I’d never have found it. Thanks for that.

[sandopolo]

Fair enough on the sensor too. I was picturing it as a detectable event, but if there’s nothing measuring anything down there, there’s nothing to detect.

The part I’d still argue is the slice time figure. RetroSharky pointed me at the Purged column and mine was 204 g across 474 changes, which is more than the model weighed. I’d sliced the job without ever opening that panel, and I don’t think I’d have chosen the same container if I’d seen the number first. It’s not a prediction of how the pile stacks, just the total mass going down the chute, and that alone would have told me my bin was the wrong shape for the job.

Anyway, cardboard box it is. Wider than it needs to be and short. Thanks for the practical version, that’s more useful than anything I was going to design.