With all the work-from-home I’ve been trying to get my desk set up more properly with some multi-monitor mounts. I have a supply of similar/identical mounts from old business LCDs(so they have proper spring-loaded height adjustment and VESA mounting, not just little plastic bits) which seemed like a good starting point.
They all have a similar design, with a pair of slide rails held inside the outer frame by machine screws. My plan is to replace the screws with slightly longer equivalents and add a couple of pieces of L-bracket with holes drilled in the correct place to create a ‘stack’ of 2 or more of the mounts held together by screws that go through the L-bracket, through the original frame; and into the slide rails.
However, I’ve hit a little bit of a snag: I’m not entirely sure how to correctly ID the size and thread pitch of the screws the vendor used so that I can obtain equivalent-but-longer replacements. Normally I’d head down to the hardware store and ask them; but I’m trying to minimize household exposure right now.
I’ve got calipers and decent vision, so if there are any “just use these rules of thumb idiot” tips I can use I’d appreciate them; if there is some sort of ‘test plate’ with a bunch of labelled holes tapped in common sizes and thread pitches that I should add to my toolbox; would also love to know about it.
Many thanks if anyone has input(both on the screw matter specifically and on the question of whether I should really be going down a different path here).

