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I am printing Benchies at high speed, I successfully printed one at 300 mm/s. If I set the speed to 400 mm/s, the Y axis begins shifting around. This is usually accompanied by a banging sound.

In addition, the extruder motor occasionally clicks. When it clicks, the filament shoots back out a little bit.

Print settings:

  • Infill: 100 %
  • Hotend: 200 °C
  • Bed: 60 °C
  • Material: PLA
  • Infill: Lines
  • Walls: 2
  • Top/bottom layers: 2
  • Speed: 400 mm/s
  • Jerk: 400 mm/s
  • Acceleration: 1000000

I am running custom Marlin-based firmware on the stock mainboard.

The printer shakes my desk when printing like this.

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    $\begingroup$ This is very fast printing speed. Why you want to print this fast? $\endgroup$
    – kosteklvp
    Sep 29 at 12:30
  • $\begingroup$ I'm trying to print many things in a day, but I can only print one at a time because of my warped bed. At least, I think it's warped. Prints come out fine in the center, but adhesion becomes poorer and poorer toward the outside edges of the bed, to the point where it won't stick at all in about an inch from the edges. $\endgroup$
    – Proxy303
    Sep 29 at 12:53
  • $\begingroup$ What layer height do you use? $\endgroup$
    – 0scar
    Oct 4 at 14:07
  • $\begingroup$ Just the normal 0.2mm $\endgroup$
    – Proxy303
    Oct 4 at 18:49
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TL;DR: Don't do that.

Detailed answer: You need motion limit parameters that actually make physical sense, and firmware capable of executing a motion plan according to them. Your jerk and acceleration settings absolutely don't. Marlin's whole implementation of jerk is wacky (note: modern Marlin versions don't even use it but an alternative they call "junction deviation" instead) and likely to cause problems above very low values; I never was able to take it above 25 or so on Marlin without layer shifts. Acceleration is dependent on the stepper motor torque and the mass you'll be accelerating. For the Y axis, that's the bed, and it has enough mass you won't accelerate it above 12000 mm/s² or so, much less the requested 1 km/s² plus near-infinite acceleration from the extreme near-instantaneous 400 mm/s velocity change ("jerk").

The speed of 400 mm/s is achievable if you don't do it instantaneously. Stepper motors begin to rapidly lose torque beyond a certain speed due to limits on how fast the magnetic field can build up and be reversed, which has to happen for each step. This calculator can compute the limits if you know the properties of your motor. For the Ender 3 Y axis motor, the limit is around 425 mm/s or so if I'm remembering right.

For actual print speed, though, the hotend and extruder cannot keep up with anything nearly that high. 150 mm/s is about the limit with that hotend, and it might even be lower with a stock extruder. Fortunately, Benchy is mostly acceleration-bound, not top-speed-bound, so if you can get your acceleration profile right, you can still print quite fast.

Now the next limit you'll hit is Marlin. Marlin is... not good at high speeds and accelerations. Often the layer shifts you hit with Marlin aren't even physical limits but Marlin bugs. If you want to go fast, you need Klipper, not only because it lacks these step timing bugs, but because you need its Input Shaper feature to keep the high acceleration from tearing your printer apart (literally, vibrating all the screws out!).

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  • $\begingroup$ I printed a benchy at 300 mm/s and it came out fine. Actually it did surprisingly well. I set the speed to 150 mm/s, then on the printer's main screen turned up the print speed to 200%. $\endgroup$
    – Proxy303
    Sep 29 at 12:48
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    $\begingroup$ @Proxy303: How long did it take to print? I have a strong feeling it did not actually print at the speed you thought it did. $\endgroup$ Sep 29 at 13:02
  • $\begingroup$ A benchy with the same settings except print speed usually takes 4-5 hours. (100% infill). This one took 58 minutes. $\endgroup$
    – Proxy303
    Sep 29 at 13:10
  • $\begingroup$ @Proxy303: 4-5 hours for a benchy is pretty long. Why are you printing with 100% infill? You shouldn't change print speed in printer's main screen. $\endgroup$
    – kosteklvp
    Sep 29 at 13:55
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    $\begingroup$ Follow-up: I missed the 100% infill - that will add some time. Sliced for 100% infill with 150 mm/s and 10000 mm/s² for the solid fill, I get an estimate of 39 minutes to print. I'm not going to actually waste the material to print it but these estimates are usually very close to actual. $\endgroup$ Sep 29 at 17:17
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Ok, so you are having multiple problems, lets break it down:

At the speed you are pushing, it would not be weird to have the Y belt slipping around. Also inertia comes into play, so please, dont do that.

What you are mentioning about the filament going out a bit, also makes sense. You are exceeding the max volumetric flowrate for the ender 3. I would recommend going for a higher flow nozzle/Hotend combo.

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