why upside down. kitchen worktop jig

[cult]

Why does this first guy cut the kitchen worktop upside down for both male and female cuts on these 2 videos but then on the other videos, the other guy is cutting his face up.

https://youtu.be/_4YyrWyOTOE

https://youtu.be/YUPwiPA7g0E



https://www.youtube.com/watch?v=r9itxGKPt5I



Another question about the cut. This might be a silly question but If ones base unit is solid on top, is it as simple as just cutting it so i can scribe under for the mitre cut. Reason i ask, why is it the base unit came solid on top and not with an opening on top.

 

[RobinBHM]

The direction of cut determines which side.

You always want the cutter to cut into the start of the masons mitre to avoid breakout.