[Question about acceleration jerk]

Hello,

Some questions about jerk.

I think i have got the meaning of it all right but do i also apply it correctly?

Jerk speed is the instantaneous change of speed that can be made. If the jerk speed exceeds the allowable jerk speed (as in example 1 ) the speed needs to be slowed to satisfy the equation.

 

In this situation a direction change of 30 degrees is made, a nominal speed of 60mm/s is desired but not feasible (see figure below ) exceeds jerk (20)

The nozzle needs to be slowed down to 38.64 mm/s if i got my maths right and the trapezoid (of the nozzle?) should look like the figure below (speed-distance chart)

 

Am i right or screwing up already?

- But how are the x and y axis controlled, they should have different acceleration speed during their path?

- Can anyone explain me how its done?

Thanks.

 

[Extrudate calculation]

Hello,

I’m doing some research on Cura with my Ultimaker² momentarily on how it calculates the amount of extrudate, E-values.

I saw a topic on extrudable.me about how to calculate the difference between the expected volume and the extruded volume. http://www.extrudable.me/2013/11/03/slic3r-strange-defaults-causing-qu-bd-woes/

But if a do so the expected and extruded volumes don’t match up (see figure).

What am I doing wrong?

 

 

The g-code is some lines from: UM2 - Extrusion Test - NoRet - 3-10mm3.gcode

With I belief a width of 0,4 mm (nozzle size) and a layer height of 0,25mm.

My formulas are in yellow.

Can anyone explain where the difference comes from?