Hey guys, what size wrench hole is needed to be drilled in the extrusions? I measured the hole in Misumi’s cad model and its over 7mm! That seems a bit larger than the diameter of a m5 button head. I’m using OpenBuilds 2020 for this.
Whatever the m5 go through is my guess.
Yeah I know, it was silly. Was just making sure 
M5 == 5mm diameter thread, M4 == 4mm thread etc. This does not account for thread pitch but assume standard pitches unless otherwise designated
Let me clarify. I’m talking about the holes that go straight through the extrusions to butt up the corners instead of having to use corner brackets. Anyhows, m5 it is.
The end hole size varies with different extrusion manufacturers, some are 5mm some 6mm, Im not sure on misumi. I use kjn extrusions.
When I used openbuilds extrusion, i drill using the next larger Imperial drill bit. Seems to work.
The hole only needs to be large enough for the Allen wrench to pass through. The button head doesn’t go all the way through the extrusion, only inside the track on the near side to the mating extrusion. The hole is so you can tighten it. I used a 5mm bit.
Wow. A picture sure is worth 1000 words. I had been thinking the screw went through both extrusions, so I was a lot more worried about how precise the holes needed to be than is actually necessary. This seems easy enough. Now I might actually get around to doing it. 
Thanks!
EDIT: I feel like an idiot for not understanding this sooner.
@SirGeekALot exactly why I decided to ask. I’m glad I did. Hopefully a future builder will find this helpful. Thank you @Eclsnowman for the photo.
So why did the build go this direction instead of the 3 way corner blocks?
Cheaper and (if you cut square) more accurate.