17/64″ HSS Jobber Drill Bit 135″ Split Point Black Oxide
In order to make extra holes in the female bracket, first we need a 17/64″ Cobalt Jobber Drill Bit (or you can use even a 7/64 inch bit).
This is the bit you need to pre-drill the hole for then tapping (thread) the hole with the #18 5/16 tap bit.
If you are using set screws, you will need a 17/64 HSS Steel Drill Bit to drill the pilot holes for the set screws.
5/16″ – 18 HSS Plug Taper Bit
Once we have drilled the initial hole, we then need a tapping bit. We can use a Bottoming Tap, a Plug Tap or a Taper Tap.
For our use, we prefer a Taper Tap Bit 5/16 Inch #18. These taps narrow a bit at the tip, therefore they can be inserted easier into the hole we drilled earlier.
The 5/16″ – 18 HSS Plug Taper Bit will create the threads needed for the hole.