This new setting is a godsend for A series printers when printing tall narrow objects. Once I figured it out, I can successfully slow down print speed gradually making for a much safer print on certain tall objects that are prone to being thrown off the build plate at normal speeds.
That said, I found the default values in here to be extremely odd. 100,000mm/s acceleration? 1000m/s print speed?? what?? At a minimum, these need to be the default speeds from normal print speeds, but given that the whole point of this feature is to slow down by height then the default values should do that by default!
Speed at starting height: 250 mm/s (general default speed for normal printing)
Acceleration at starting height: 6000 mm/s (the normal printing default… 100k is a bug?)
Ending height: 256 mm (where did 400 come from?)
Speed at ending height: 125 mm/s (50% of starting)
Acceleration at starting height: 1000 mm/s (1/6th of the starting speed, high acceleration is the major cause of failure for tall thin prints on bed slingers)
^^ These would be much better defaults at least, then people can adjust if needed, but at least these make sense and actually WORK as a starting point without causing problems.
I disagree, i dont think speed is the right lever to pull, Acceleration is. It’s easier to think about in terms of speed, but newtons being pushed into the plate by the Y axis is what causes floppy cartesian prints. Acceleration is the thing that controls your newtons
In either case, 100k as default is crazy. Tapering from 5k → 1k should be good enough to control the flop
Thank you, I saved these as a print profile in Bambu Studio so that I could call them up on demand. I did lower the numbers in what you suggested about 20% and made the slowest speed 60mms at 256mm. I regularly print some tall cylinders (pocket toothpick holders) a dozen or so at a time, so I took a more conservative approach. Appreciate the post!
makes more sense than speed. Does that also define the deceleration? The wobble is created from the change in speed. I would guess it would be better to have a start and end. Not set of ranges. Maybe I am missing why it is said a speed present change. In changing the acceleration is not really changing the short segments. But the long segments change significantly.
Physics: if speed is the change in distance over a time, accel is the change of that (speed) over time, and jerk is the change of THAT (accel) over time. Accel is just applied in a different direction to “slow down”. Apply force at stepper motor into carriage via belt, frame takes the normal force, carriage accelerates.
Jerk is harder to quantify and relate to, but it’s like… Driving a car. And that last 1% of braking where the pads mechanically stop doing moving friction and are now (more powerful) static friction, and they abruptly “jerk” the car from 0.5mph to 0. That sort of “burst” of applied force. I dont have the engineering background to describe how a stepper motor controls this but I imagine it has something to do with how fast the electromagnets are turned on and off.
True the deceleration is acceleration, just a negative value. I have not looked into current g-code to know that the deceleration is controlled. I am guessing it depends on the slicer. Rapid slowing is effectively the same as rapid speeding up. Causes wobble of the part.
More the acceleration that causes the wobble, that causes print issues.
to be truly pedantic, deceleration is acceleration, just a different and often opposite vector direction. No such thing as negative time or negative speed, no way to get a negative out of that calc
all numbers are not real. It depends on what coordinate system is used to simulate. If you are using vector coordinates it is opposite direction. If you are using Cartesian coordinates it is negative. No right or wrong. This is getting too nerdy. LOL
