Are you sure it's 5/8 NPT? What makes you think that?

Home Depot sells adapters from pipe threads to hose threads and the male
3/4 pipe threads x male hose threads are hard to tell apart. The
difference appears to be that (1) the pipe thread is tapered and (2) the
hose end has a flat surface for the washer to bear on. The hose fitting
has only a few threads, so I can't see if they're tapered, but I suspect
it's not a NPT size at all. There's no reason for it to be a pipe thread
since the hose is sealed to the faucet by a washer rather than jamming
two tapered threads together.

For a single faucet repair, it seems like overkill to buy a die
(probably $20-50 for a special size) to clean the threads. Two
possibilities come to mind: (1) you can take a triangular file or a
dentist pick and clean out the threads with some careful hand work.
(Your dentist probably throws out worn dental picks, so you might check
with him/her.) This might take an hour, but you have probably already
spent that much time trying to find a die. (2) you could replace the
faucet with a new one (cost around $5-15 including a few fittings). This
might require some interior plumbing, but it's within the capabilities
of the average homeowner. Most exterior faucets (at least in New
England) come with an indoor shutoff with a drain so you can keep the
faucet from splitting in the winter. That makes it fairly easy to
install a new faucet after that point. And also to shut off the water
when you really screw it up.

If you're doing some other plumbing, it might be easier to get the
fittings from a plumbing supply house or Home Depot. They have both male
and female hose ends, also swivel hose ends (the standard female hose
fitting found on the hose). They come with 3/4 or 1/2 pipe threads on
the other end, male or female.




Ol' Duffer wrote:
I'd like to have a tap and die set in 5/8" NPT.

Why am I posting here? Because I bet nearly all of
you have lots of stuff in this size and didn't even
know it. I believe it happens to be garden hose size.

I have an exterior faucet with the threads grown up
with mineral deposits so that I can no longer get a
hose screwed on, and would like to chase the threads.

For some obscure reason, all standard tap and die sets
for plumbing skip from 1/2" to 3/4", yet 5/8" became
the standard for garden (and some washer) hoses.

Obviously, the folks who make faucets and garden hose
stuff have tools to make these threads. Anyone familiar
enough to point me to a source?