Why the estimates so different when just swapping the nozzle

Bambu Lab H2 Series
1

So the grouping Bambu Studio says to do is 4 colors on the left nozzle and 1 color on the right.
It estimates 1063g at 2 days 3 hours.

My AMS is connected to the right nozzles. I go into custom group and all I do is reverse everything. Same color grouping, just the 4 colors on the right nozzle and the 1 color on the left.
It estimates at 1235 at 2 days 6 hours.
I fail to understand why this would increase the filament by 175 grams and more time. It states 0 changes compared so it is the same exact swaps. The purge is the difference.
purge 418 vs 246. For the life of me I can not explain why this would make a difference.
Also notice the purge abount on the right nozzle is more than on the left nozzle. I bet that would be it, Just not sure why one nozzle would need to purge more than the other.

Any ideas?

2

H2C or D?

 
 
 

3

H2D is what I have. sorry.

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4

You’ve tried resetting the prime volumes for each extruder?

So here’s something I never realized/noticed before. In printer settings, the “Nozzle Volume” read-only property for Left & Right Extruder are different, with right side having a higher volume:

  • Left: 130 mm3
  • Right: 148 mm3

Reading the tooltip for this property, it’s actually the “Volume of nozzle between the filament cutter and the end of the nozzle.” So I guess the difference makes sense since the left nozzle lifts up. And I’m presuming this is the (minimum) amount of filament that needs to be purged between each color swap, at least on a D.

I guess depending on the number of color swaps, the 18 mmÂł difference could add up.
“Back of the napkin” calculation, using basic PLA @ 1.28 g/cm³:

  • 18mmÂł ~= 0.0227 g
  • 175 g / 0.0227 g ~= 7709 swaps.

That seems like a lot, but my calculation is also presuming a lot.

Otherwise I don’t see what the difference between left and right nozzles would be on a D, or how/where those settings would even be visible. Only regular vs. high flow. :person_shrugging:

Cheers,
-Max

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5

interesting, that would make sense. With tons of swaps that would make a difference. that is why it wants most the colors on the left nozzle and not the right. But they recommend adding the AMS to the right nozzle. With all this, I may just move my AMS to the left and my AMS HT to the right.

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6

My first guess was the purge volume also.

Because there can be differences also between the switch from dark to light and light to dark cololrs, so the order of colors has an influence also.

However the distance of the filament cutter hadn’t come to mind yet. :+1:t4:

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