In article , Carlos Valor
says...

looking for recommendation on how to drill a 1" deep 5/16" diameter
hole in the end of a steel 5/8" bolt. it is crucial that the hole be
centered and parallel to the bolt axis.

You've been given a number of different ways to perform this
task. The most difficult part however is still up to you:

You need to decide on a tolerance for your piece. How
accurately does the hole need to be placed in the end,
and how much deviation from the axis is permitted?

The answers to those two questions cannot use any of the
terms:

Dead Nuts On
Absolute
Perfect
etc.

The answer will be something like, I need the hole to be
in the center of the bolt within +/- 0.003 inch, and I need
the other end of the hole to be within 0.001 inch of the
location of the hole's top.

Remember that a) you will have a tough time indicating
to the threads on a faster, so unless there is an unthreaded
portion, you might be doing well with *five* thou accuracy.
And b) often the hex heads on fasteners are poorly aligned
with the shanks. Consider what the function of the hole
is to be, before deciding what is to be aligned *with*.

The easiest, fastest way: a lathe.

If you do it on a drill press, here is one way to come
close: swing the table off to the side, and clamp a thick
aluminum plate so it overhangs under the quill. Carefully
centerdrill a starting hole, and enlarge it to the size
of bolt you you are using.

Without moving the table, fasten the workpiece into the
hole and repeat the process - the hole is roughly aligned
with the quill's axis. The tighter the fit of the bolt
in the hole, the better you will do in terms of accuracy.
For this aproach, +/- 0.010 inch is about the best you
can hope for.

Jim


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