When creating a loose thread from tapping use a larger drill bit.
From Morse Cutting Tool’s “Machinist’s Practical Guide”:
Example: screw size #0-80
Body drill: 52
Size or number of drill for percent of full thread
100% tap drill: 58
80% tap drill: 57
75% tap drill: 56
70% tap drill: 56
60% tap drill: 3/64"
50% tap drill: 3/64"
“A 53% thread will break the bolt, before it will strip - in most
“A 100% thread is only 5% stronger than a 75% thread, but it requires
three times the power to tap.”
Most of the work I do (steel, ss, polymer, aluminum prototyping) is
cut at 75% full thread. I might index one drill bit size larger than
recommended if I’m in a hurry on non-critical stuff.
Off list I can give you the drill bit numbers for the taps you are
working with. For very thin stock, you will want to use 100% full
thread, whereas the above is for holes as deep as the diameter of the