I'm looking to make a desk for myself. For the surface, I'm planning on using an oak kitchen surface (either 30mm or 40mm thick) and I'll have 4 60mm holes cut to support desk grommets for cables, usb ports and a wireless phone charger.
My plan was to put the holes 50mm from each edge (or 80mm to the center point of the hole) but I have some concern about whether I'll be undermining the structural integrity of the back of the desk too much. If I mount monitor arms to the back of the desk (2, around 10kg weight on each), is the back likely to snap off under the load?
My initial thought here was to model the back of the desk as a 1600 x 50 x 40 shelf with a 20kg load. http://www.woodbin.com/calcs/sagulator tells me this will be fine but I'm unsure if that's the best way to think about the load here - I think I need to be more worried about the stress on the wood between the holes?