Tl;DR
- Whoops on the tool speed.
- Acceleration is incredibly important to achieve faster prints and the primary path
- 35mm3/s is pretty achievable nowadays
- High voltage is an important feature to accommodate high speed tools and increasingly quick printers
- All of this is moot if the intended toolspeed is 200-300mm/s or less.
@deckingman said in 48 volt steppers board selection:
"I accelerate this mass at 1500mm/sec^2 up to 350mm/sec "
My bad - not sure why I saw 150. Maybe I conflated the 1500 with the 150 in my mind. not sure. I'll own it.
Regardless - 350mm/s tool speed (assuming that you're printing with a .4mm nozzle, .48lw, .2mm layer height) is only 30mm3/s, pretty medium-flow nowadays. Slice Magnum, Takoto, HF Dragon, Rapido, HIC, Nova, and the standard volcano is all in that range, with some in this list well above those capabilities. There are even higher-flow hotends in the market, starting with the Rapido, HIC, VolcanoMosq, Mag+, and a few others out there. I'd say a sizable portion own a hotend capable of 30mm3/s, especially if augmented with something like a CHT.
Re: acceleration - the below plate is assuming 400mm/s print speed, 15k acceleration, 8mm/s instant velocity change, except for the first layer. 4 perim, 40% infill. Its predictions are pretty bang-on compared to as-printed, within ~2% of predicted with this profile and this plate.
This is the same plate, except I've dropped the acceleration to 1500mm/s/s
Now - what happens when increasing the acceleration to 4500?
You save an estimated 5hours of print time, and use 13.5N of force instead of 4.5. That adds up after a while.
Lets go to the ultimate "theoretical" limits - does it fall off? you have 3kg gantry, and a conservative estimate of 234N of force, so you can accelerate at a theoretical 78k mm/s/s.
Obviously mechanics won't allow this to happen, but at least lets see what happens to the print times. I've verified that the slicer decreases time alloted beyond 78k accel, so this model should be accurate.
All the way at 78k, you've only saved another 2hrs beyond the 15k estimate. This is where these diminishing returns are really found, assuming your hotend is limited to ~35mm3/s.
But, increasing acceleration is the best real way to increase speeds - increase your jerk too much, you get ovals instead of circles, lose corners, and all sorts of other bad behavior. Acceleration is something that can be increased near infinitely, assuming that you have the power and rigidity to do so, among other plastic-melting limiters.
But, the point stands - at 15k, I can double my productivity over 1500. At 4.5k, I save an appreciable amount of time that adds up. its not inconsequential, and assuming that your machine is built correctly, quite repeatable.
All of this was done without fiddling with the Z-axis speeds - if I switch to a belted or a faster Z, this gets significantly better as alot of this time may be calculated from z-hop.
But, many Common hotends out there can easily go past 35mm3/s - This is where the high speeds and high voltage come into play, and something that is important to address. One can't effectively use high-flow hotends if their tool never gets to the high speed, necessitating high acceleration, demanding high torque.
