Drill size

[jcnewbie]

Hello I am programming a lathe part and wanted confirmation.

I am going to tap using a 3/8-16UNC tap, is the correct drill size 5/16 ? Could I use a 7/16 drill as well ?

[dertsap]

5/16 is the proper size . 7/16 is .0625 larger than your tap dia

[snkdriver]

A lot of tool suppliers have free tap drill charts for the asking. A simple formula for calculating the tap drill for a 60 degree v thread is :
Major diameter minus pitch. Works for inch and metric. (60 degree only)

[Perfect Circle]

Here is a chart you can print out...

Tap Drill Sizes

[littlebrewman]

anyone machining should have a machinerys handbook.it is the machinists bible.how could not have a tap drill chart with all of the sources for one i.e. internet. this to me seems like a stupid question to be posted.

[ObrienDave]

Yes, you could use a 7/16 drill.
If you needed a clearance hole.
Geez Louise