“Preferred” doesn’t mean “all the time”. But chamfers are easier to get nicer results with the majority of the time because they are easier for the printer to make.
Fillets are easier to print horizontally than chamfers as they spread the acceleration (i.e. the thing that makes sharp corners bad) over the while fillet instead of just splitting it into two stages like a chamfer would.
Chamfers are easier to print vertically than fillets as the overhang is limited and consistent.
There’s no overhang for a horizontal corner as you’re printing the same shape onto the layer below, and no acceleration for a vertical corner as it’s entirely separate layers so the toolhead never has to follow the path of the corner.
It sounds like you’ve read (or only remembered) half a rule. It’s not the case that either half of the rule is used the majority of the time because 3D printers are used to print 3D objects, so they always produce objects with both horizontal and vertical edges.
“Preferred” doesn’t mean “all the time”. But chamfers are easier to get nicer results with the majority of the time because they are easier for the printer to make.
Fillets are easier to print horizontally than chamfers as they spread the acceleration (i.e. the thing that makes sharp corners bad) over the while fillet instead of just splitting it into two stages like a chamfer would.
Chamfers are easier to print vertically than fillets as the overhang is limited and consistent.
There’s no overhang for a horizontal corner as you’re printing the same shape onto the layer below, and no acceleration for a vertical corner as it’s entirely separate layers so the toolhead never has to follow the path of the corner.
It sounds like you’ve read (or only remembered) half a rule. It’s not the case that either half of the rule is used the majority of the time because 3D printers are used to print 3D objects, so they always produce objects with both horizontal and vertical edges.