In article 1119705063.093562.181590
@g47g2000cwa.googlegroups.com,
says...
I am building a jig to drill and tap a series of holes. In operation,
the jig will have slip fit style drill bushings. I will drill the
pilot hole, then run a tap thru the hole. I was planning to use a
drill bushing that fits the thread cutting end of the tap, but don't
have all the taps that I am going to need yet, so I do not have a way
to check what size of drill bushing will fit the tap properly. The
sizes I will be using a
5x40 & 6x40.

Does anyone know of a formula, or real world answer to this question?
TIA, ron



Machinery's Handbook shows the major diameter of taps in
the "Taps and Threading Dies" section. The major dia of a
5-40 ground thread tap is .1275/.1265, 6-40 is .1405/.1395

Ned Simmons