Several ways to skin this cat. Now that I see Thier part I see that the bolt head is recessed so that you can loosen the turn wheel enough and just rotate it out of the way. So whatever way it is made the bottom would need to remain smooth to allow that function.If it's just a recess for the head of the bolt it actually could be drilled 3/4 of the way threw and tapped for a treaded rod. That would be the easiest way. Instead of cutting the hex in. I'm also a cnc machinist/ programmer. Been doing this for 15 years
Can you still get these pleaseHi, I am too new to PM you apparently, I am very interested in order 2 sets of these for my FX5, could you pm me or email me at c_steig@hotmail.com
Thanks
Connie