I took this screen clipping from the Bambulab Store product listing for the H2D HF 0.4mm nozzle:
I think I understand the meaning of the first 3 filament columns, but what is the meaning of the last column?
It is the maximum amount of plastic a printer can extrude per second, typically measured in cubic millimetres per second (mmÂł/s).
Right, but doesn’t it depend on the plastic? That’s why the first 3 columns makes sense. The last column doesn’t name a plastic, though, so what does that even mean? Is it the theoretical maximum speed that the extruder can push a 1.75mm filament, assuming no resistance at all? For example, with the hot end removed? No, it can’t be that, because the difference is due to whether the hotend is HF or not.
It represents the highest possible flow rate of filament through the hotend.
It helps to prevent issues like under-extrusion, where the printer fails to deposit enough filament, leading to poor quality prints.
Bambu Slicer uses the value to determine the maximum speed at which a print can be performed without exceeding the hotend’s capabilities.
It is a value based on the printer and the hot end assembly as a whole.
This is why the HF nozzle has a different value, it is capable of receiving material faster than one that isn’t.
Since I dont see different ratings for different nozzle sixes, im assuming thats how fast the extruder could theoretically push filament with no resistance(max speed of the extruder servo)
It wont let me edit my post but i would think .2 would be different than .8 nozzles
Based on the speed of the h2d and the x1c with its nozzle rating, this 65 has to be theoretical.
Here’s my opinion on what these numbers mean. It is the highest theoretical limit of the nozzle’s ability to transfer heat into liquid plastic under optimal theoretical conditions. I believe this is based on the inner surface area and the wattage of the heater cartridge. Nothing to do with the ability to actually use that much plastic and have a reasonable outcome(at least with a 0.4 nozzle.)
IMO a 0.4 nozzle with a multi chamber flow path (CHT?) is completely worthless, especially when the original H2D nozzle can easily flow 25mm^3/s (I’ve personally been able to hit 30-40mm^3/s with ABS and ASA during testing) which easily bypasses the flow required for any reasonable printing speeds with a 0.4 nozzle. Any faster xy velocity and the print quality takes a big hit anyway. The only time you would be able to effectively use that much flow is a 0.6mm nozzle or bigger.
With the current motion system being so good it’s easy to run just ludicrous mode and receive almost 0 penalty, at least thats what i get most of the time with large rigid parts.
Regular usage of ludacris mode is a clear indicator of incredible laziness or complete lack of understanding of the slicer.
Or you could say, if you find that ludicrous mode works consistantly with a specific filament, you should then make a custom profiles with the changes. Max flow, accelerations etc.
Why would you have to turn everything into an argument? The mode exists and it’s just a easy way to boost acceleration and speed limits to 166%. Making a profile for each and every filament you use is extremely inefficient and time consuming. I have over 16 brands and >30 different filament types in stock, good luck on getting them all finetuned with countless hours of calibration prints.
This is the first reasonable use of these buttons I have heard of. My niche usage case is when I have a model with a point at the top and I have slowdown for layer time but I don’t really need it. In this case I know I can “push the limits” because the printer is already moving very slow. Noobs just turning on Ludacris because printer go brrrr and then crying about quality issues grind my gears. All the bambu FB pages are filled with these.
I see a few others have explained it already. Just wanted to throw out there that I’m pretty sure they use ABS to test the max volumetric flow rates.
Why are you pretty sure? Does it align with what you measured?
Most speed ratings on equipment that manufacturers put out are tested using abs.
The single wall cylinder print using ABS notated in number 1 is how they got the max volumetric flow rate
Number 2 with the pla cube is how they figured the percentage of time savings in the paragraph above the chart on the website.
I don’t print ABS and rarely do vase mode cylinders, so I may never see that flow rate.
Very interesting! The quote is taken from the same link I posted in the OP.
At least on first blush, I think maybe you nailed it. 
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Assuming that’s the answer, wouldn’t you agree they should have labeled that column as ABS though?
100% in agreement with you. When I first got my Ali CHT and E3D HF nozzles for my X1 and P1s I went down the rabbit hole of creating custom filament and speed profiles for each brand and type I had and as I mostly used 3rd party filaments I very soon hit the upper limit of filament bambu will sync to the cloud. Eventually I realized the flow is increased by about 50-60% with HF nozzles with common filaments like PLA, ABS and ludicrous mode increases the speeds by the same amount and also bumps the acceleration. I still do max flow test and custom profiles when Im trying to print at the highest quality, but for prototypes and drafts ludicrous mode is a nice shortcut.
Now that I got the H2D Im not really bothering with custom filament profiles except “Generic TPU” and a few others. Also as auto PA calibration is much improved with H2D, I absolutely see no need for custom profiles for each filament brand and type, with very few exceptions.
They should have, but I guess it doesn’t look as good as just saying the hot end itself is good for 65 lol.
I am confused; you wanted to know what Maximum Volumetric Speed means, specifically concerning the last column, which is labelled Maximum Volumetric Speed (the same thing).
Things veered off to trying to work out if the last column means a specific material, which it doesn’t. Nothing in the notes 1 & 2 relates to a direct correlation with the last column, simply their explanation of their testing regime.
Nope, for the reasons above.
That’s not the answer; that is a testing note about how they performed their test.
You had the answer.
You had a follow-up to the answer.
Now you have linked a reference to a testing note and postulated if there was a correlation they failed to write (as in the material), there wasn’t.
They could have selected ASA as the testing material, but it wouldn’t have made the final column ASA-related any more than it currently makes it ABS.
I hit this limit a long time ago, even before getting my H2D. Is there any way to get a higher limit? A one-time payment, a subscription,…, anything? It’s immensely irritating, especially given what should be the extremely low cost for the data storage. The number of bytes needed to preserve each profile should be paltry. I’m sure I’ve uploaded orders of magnitude more bytes just from all the photos I’ve posted to this forum.
