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?

Use a wire brush.

--

Travis in Shoreline (just North of Seattle) Washington
USDA Zone 8
Sunset Zone 5