Simplify3D User Forum

When I add M83: Set extruder to relative mode to the start script like I do in Prusa Sil3cer the printer goes nuts and tries to extrudes more filament than the hot end can melt causing the filament to grind and the print failing

Is S3D unable to use M83 and M82 in the start script g code

There is an option on the G-Code tab of your process settings for using relative extrusion distances. If you enable that, it will already include the proper M82/M83 command at the start of the file, so no need to add it yourself.

I'm guessing you didn't set that option correctly for what you wanted to use.