05-01-2020, 08:31 PM
(05-01-2020, 01:59 PM)EdK Wrote: I use these types of counterbores I get from McMaster.
https://www.mcmaster.com/counterbores/me...nterbores/
I buy them as I need them. I think I have them for #4-10 screws, 1/4" & 5/16" and maybe a metric one or two. Going from memory so might not be accurate.
They are pricey but once you've used one you'll want more.
Ed
EDIT: Oops! These won't work for threaded holes. The pilot size is larger than the bolt size.
Interesting. I thought those short ones were "porting" tools?
For installing fittings that need a flat sealing surface for o-rings and such? Maybe they just look similar. Obviously there is more to these things than I realized. 
But the drill tip got me thinking because it looked familiar and I had to go look at my set. What I have now are actually step drills - or I guess you could call them drill / counter bore combination bits. Just a longer version of what you have Ed.
Willie