Change speed at Z not working

[ender3max 0]

I want to print my model at 100 mm/s from the 67th layer to the 178th layer, and print the rest at the model at 50mm/s. I have created two scripts to increase and decrease the speeds using the Change at Z Plugin. But when I look at the speed colour scheme there I see there is no change to the speed. Do you know what is causing this and how can I fix it?

[GregValiant 1,251]

The top of that model isn't very big so you might be bouncing up against the "Minimum Layer Time".  The default is 10 seconds but if you lower it too much you won't get sufficient cooling and the top of the model may suffer deformation.

 

I recall that "ChangeAtZ" did not play well with Z-Hops enabled.  The Z moving up and down confused it.  If you have enabled Z-hop turn it off and see if it makes a difference.

 

If you open the Gcode file in a text editor you will see "F" numbers in some of the lines.  They indicate the feedrate in mm/minute.  50mm/sec would be F3000 and 100mm/sec would be F6000.  If you look around layer 150 you may see numbers like F2476 or something else that wasn't one of your settings.  That would indicate that Cura made an adjustment to slow the layer down so it would take longer than the "Minimum Layer Time".

[ender3max 0]

Thank you for the reply. The gcode just uses F3000, so I don't think minimum layer time is interfering, and I don't use z hop so that can't be the problem either. Is there another way to do what I want as change at z has some issues for me?

[ahoeben 1,948]

The Gcode postprocessing is not performed until you save the gcode, so it is not showing on the preview tab.

 

The plugin does not affect all the F-values in the gcode after the change, but inserts a single M220 gcode command to instruct the printer to "multiply" the F-values internally:

https://marlinfw.org/docs/gcode/M220.html