wrote in message
oups.com...
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


The formula for numbered screw sizes is the size times .013 plus .060. So,
a 5-40 would be (5 x .013) + .060 or .125. A tap will be a couple thou
bigger than the screw.

Jerry