Is Y endstop min or max?



I am new to 3d printing and I just finished assembling my Wilson II.
There is something bothering me about the Y endstop. It is said in the video tutorial to plug it in the Ymin position of the RAMPS, but to respect trigonometric direct angle shouldn’t it be an Ymax? (with X+ going on the right and Z+ going up).
It seems it is not possible to easily compile Marlin with only a Ymax endstop (error “Enable USE_YMIN_PLUG when homing Y to MIN.” in SanityCheck.h).
Do we don’t care about respecting direct direction? In this case will the part I will print will not be mirrored?

I guess I am missing something obvious, but what?



You lost me at this and I’ll have to google it but in all the different variants of the “Prusa I3 style” 3D printer’s I have built, Y0 is always at the rear or the bed is furthest from the front and this is where the endstop is positioned.

I did try to setup a printer using X max instead of X min but it was at that time a pain as I think a lot of the code was “hard wired” but it should be possible to with the later firmware.

One thing I would like to try again, is to use both Min and Max endstops like CNC machines do but this was also a difficult thing and although it seemed to work in practice the Max endstop was ignored when printing.


In fact, my question raised when watching this video ([2016 version] How to set up the Marlin firmware!), but that’s all right, I just missed the thing he said previously: movement are considered from the nozzle, and indeed with a moving bed, it must go toward you for the nozzle to advance on the Y axis in the good direction.