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Does printer speed control change acceleration and jerk, or just speed?

PCLoadPLA

Does printer speed control change acceleration and jerk, or just speed?
May 22, 2024 11:03AM

Registered: 3 months ago
Posts: 37

I just upgraded to Marlin 2 and a cool touch screen.

I can see the option to adjust print speed in real-time, and it does work. My question is does it scale print speed parameters uniformly by just changing the kinematics tick rate, which would adjust speed, accel, and I guess jerk as well, or doe it just change the G1 Fxxx commands to reduce the linear speeds?

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Dust

Re: Does printer speed control change acceleration and jerk, or just speed?
May 22, 2024 11:31AM

Admin
Registered: 13 years ago
Posts: 7,108

Its a simple percentage multiplier of the F value

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PCLoadPLA

Re: Does printer speed control change acceleration and jerk, or just speed?
May 22, 2024 12:05PM

Registered: 3 months ago
Posts: 37

OK that makes sense. Another question though, how is it implemented? The microcontroller streams gcode off, in my case, the SD card. So the TFT display can't intercept that and scale the F values. Is there a Gcode that does to Marlin itself that tells it to scale the F values?

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Dust

Re: Does printer speed control change acceleration and jerk, or just speed?
May 22, 2024 12:21PM

Admin
Registered: 13 years ago
Posts: 7,108

there is a gcode, [marlinfw.org]

the gcode and the screen UI update the variable feedrate_percentage

This defaults to 100% and is always being applied, so when you change it to a different percentage it speeds up or slows down

Edited 2 time(s). Last edit at 05/22/2024 12:29PM by Dust.