Linearly Reduce Print speed

[utkudemi 0]

Hello,

 

How can I linearly reduce print speed ? I have a tree like model which tapers at the top, and I want to print slower as layer number increases, since this will reduce the shaking effect at top layers. ( I have ender 3 pro, table not static )

[vuldust 0]

I dont know if there is a feature in cura to control that.

 

You can manually edit the gcode and adjust the feed rate but not sure how that would affect the extruding.

Would assume you would need to adjust both but that extruder would be difficult to modify in the g code file.

 

Could just play around and see what you get though.

 

If you need help let me know.

 

 

Edited January 27, 2022 by vuldust

[GregValiant 1,436]

The only setting that will affect the calculated speed in the gcode are "Minimum Layer Time" and the related "Minimum Speed".  If Cura detects that a layer would go down too fast so that a previous layer didn't have time to cool) then the speed is adjusted so that the minimum layer time is met.

 

There are a couple of things you can manually add to a gcode file.  I also have an Ender 3 Pro and on tall models I add an M201 Y300 line at around a Z of 100.  That limits the accel on the Y axis so the print doesn't shake or break loose.  You can do that with a search and replace like:

Search = ;LAYER:500\n

Replace = ;LAYER:500\nM201 Y300

The check box for "Use regular expressions" must be checked so the "\n" newline expression is acknowledged.

 

You can do the same sort of thing for speed using a couple of Search And Replace instances.  M220 S80 would reduce the print and travel speeds to 80% of whatever is in the gcode.

Search = ;LAYER:500\n

Replace = ;LAYER:500\nM220 S80

and a second instance of Search and Replace could be:

Search = ;LAYER:750\n

Replace = ;LAYER:750\nM220 S60

Once again, the "Use Regular Expressions" box would need to be checked.

 

Something like that should work.  You can hand code them in at the appropriate height as well.  I have M220 S100 and M221 S100 in my End Gcode to reset the feed and flow rates to 100% just in case I make adjustments during a print.