If I create a new project in bambu studio, add an object, assign a filament (such as PETG, ASA, TPU), I see that the print speed is still set as high as 600 mm/s, which is not realistic. Researching, most everyone says don’t touch those settings - instead, edit the filament and lower the “Max volumetric speed”. That setting doesn’t seem to do anything. It was set at 12 mm3/sec, and I lowered it all the way to 1 mm3/ec, and it still prints way too fast and the print quality is terrible. The only way I’ve been able to print with anything other than PLA is to manually lower each speed individually, making sure none of them are higher than 100 or 50 or so. Am I doing something wrong? I don’t understand how everyone says bambu presets are so good if it doesn’t even adjust the speed, trying to print ASA or TPU 10x faster than possible.
You’re not doing anything wrong, and your confusion is completely understandable — the way Bambu Studio handles speed and flow limits can be a bit misleading at first glance.
You’re correct that the speed values shown in the Quality (layer profile) tab may list high values like 500–600 mm/s, and those can look unrealistic for materials like ASA or TPU. However, these values are theoretical maximums, not guaranteed print speeds. The actual print speed is automatically capped by the Max Volumetric Speed (MVS) defined in the filament profile.
Here’s how it works:
- The slicer takes your line width, layer height, and the requested speed from the layer profile.
- It then calculates the required volumetric flow rate (how much plastic needs to be pushed through per second).
- If the calculated flow exceeds the MVS value for that filament, Bambu Studio automatically reduces the actual print speed to stay within the safe limit.
So yes, lowering MVS from 12 mm³/s to 1 mm³/s does work — but you won’t see that reflected in the numeric speed values in the UI. It affects how fast the printer actually moves at print time, not what’s shown in the layer profile.
This is why people say “don’t touch the speed settings” — because Bambu’s speed control system uses MVS as a governor to safely slow things down based on material capability.
However, if your print quality is still poor, a few possibilities:
- The MVS value for your filament might still be too high for your machine or specific spool — factory presets are not always perfect.
- Your nozzle might not be able to maintain pressure at those flows (especially for soft materials like TPU).
- You may benefit from enabling “Max volumetric speed override” in the per-object settings or setting lower acceleration values.
If you want full control and consistency, your approach of manually adjusting speeds works fine too. But yes — MVS does control real print speed, even if the UI doesn’t make that immediately obvious.
TL:DR: You need long straight paths to achieve that velocity the same way you need a long straightish runway to accelerate to highway speeds. If your model is small or intricate, it is constrained by the second and third derivatives of mechanical speed limits (accel,jerk)
That’s true, and in cases with small prints, acceleration can be a key parameter to adjust. I had to tweak those settings in my TPU profile on the X1 Carbon to achieve perfect, non-stringy results—or at least as string-free as TPU can realistically get.
The Bambu preview values are a bit like the weather forecast for the holidays - assuming the best possible case.
I got a bit confused in the beginning as well with these useless values.
Turned out though there is some logic behind the madness.
For my P1S the max speed is 500mm/s but in the slicers I saw over 650mm/s at some stage during the experiments.
The preview goes a bit like this >
The model is sliced, based on the movements the slicer calculates how long this MIGHT take to print.
This assumption is based on several factors like the max movement and print speed in each layer.
Problem is that this max speed might never be reached in this layer or only for a few mm of a 30cm wall loop.
The only half usable indication is the time to print the model.
Quite often even a drastic speed change only has a minor affect on the assumed print time…
The max volumetric speed does not provide a higher printing speed, it ‘only’ lifts a few restrictions higher.
How fast it really prints is still affected by the other factors.
Do you have HF hot ends? If yes, you need to adjust the max flow rate for HF hot ends its in a separate tab.
Hmmph! I was thinking that would automatically be set to match the “Flow” dropdown in the main slicing pane but I guess not - good catch. I updated.