# Acceleration and feedrates

 Acceleration and feedrates January 26, 2020 12:31PM Registered: 2 years ago Posts: 56
I use slic3r pe almost exclusively.

In the machine limits section slic3r is expecting mm/s².

Marlin itself has these values in config.h as mm/s.

Haven't been able to find a direct conversion from mm/s to mm/s².

For anyone curious, this makes a huge difference in the slicing logic and printer movements.

So, how do I convert, for example 3000 mm/s to mm/s²?

Thanks.
 Re: Acceleration and feedrates January 26, 2020 01:03PM Admin Registered: 12 years ago Posts: 12,536
... acceleration is not speed or feedrate!

The "3000mm/s" is the feedrate or the maximal speed for this move.

The acceleration will define, how fast you'll change from 0mm/s to 3000mm/s and the same for deccelerating before stop or starting the next line segment ...

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]
 Re: Acceleration and feedrates January 26, 2020 01:32PM Registered: 2 years ago Posts: 56
Quote
VDX
... acceleration is not speed or feedrate!

The "3000mm/s" is the feedrate or the maximal speed for this move.

The acceleration will define, how fast you'll change from 0mm/s to 3000mm/s and the same for deccelerating before stop or starting the next line segment ...

I'm not arguing this point.

What I was trying to figure out is that, marlin has their value (default maximum acceleration) defined as mm/s.

Slic3r pe expects the value of maximum acceleration for x as mm/s².

Again, I'm not trying to argue the semantics of the technical accuracy of the terminology. Maybe marlin and slic3r need to get together and coordinate the movement value definitions. This is not my doing. I'm just trying to figure out what value in slic3r equals the values in marlin.
 Re: Acceleration and feedrates January 26, 2020 07:04PM Admin Registered: 12 years ago Posts: 12,536
... so this is wrong spelling or dimension -- maybe a forgotten ² ?

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]
 Re: Acceleration and feedrates January 29, 2020 07:54AM Registered: 2 years ago Posts: 903
No error in Marlin, just a funny way to express a. May be they couldn't find the ² on the keyboard

From Marlin config.h

/**
* Default Max Acceleration (change/s) change = mm/s
* (Maximum start speed for accelerated moves)
* Override with M201

"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
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