3/8"-28 Tap Drill

[oldeskool]

We're looking for a tap drill size for 3/8"-28 UN tap. The Machinery Handbook lists this thread as existing, but does not provide a drill size. Hours of google searching by two of us has also not provided any leads. Was wondering if any of you fine people might know or had a way of finding it? Thanks.

 

[dimjim]

Machineries Handbook shows
.336 to .345 dia. for 2B thread
.336 to .3426 dia. for 3b thread
looks like an 8.5mm (.3346) drill
or an R (.339) drill will work
assuming that they will drill
slightly oversize.

 

[MikeHalloran]

0.339" or an 'R' drill should be a good start.



Mike Halloran
Pembroke Pines, FL, USA