On Saturday, February 23, 2019 at 8:14:58 PM UTC-5, Jim Wilkins wrote:
"Cydrome Leader" wrote in message
...
I've been playing with tapping plastics like HDPE and so forth and
not
surpisingly discovered that sharp taps and drill bits and not taking
small
cuts seems to help.

So the question is how does one source "sharp" taps in the 6-32 to
3/8"
sizes? Is there a certain brand or type that cuts plastic out of the
box
better? Internet wisdom seems to show that looser taps like H5 are
better
as well as they make up for the plastic shrinking back into shape.

Any other tips?

Stone (or sand/Dremel) the flute grooves to sharpen them.

https://www.amazon.com/Round-Edge-Sl.../dp/B0006NFEQG
I'm glad I bought mine before they became so valuable.

I have a 70-year-old box of slips, which I use when I can, but I still find a need for pieces of wet/dry wrapped around a nail or dowel. I haven't sharpened a tap for decades but that's how I used to sharpen them.

That's the same thing I do for many steps in building fishing rods. I usually cut a narrow strip and wrap it around in a spiral, using glue to hold it in place. It's handier than digging out slips that have different radii on opposite edges.

--
Ed Huntress