Simon wrote:

Hi, I'm cutting a 1 1/4 NPT thread in some 16mm thick aluminium. My tapping
chart says 37.5mm hole, I'm wondering if I should use a tapered reamer on
the hole first? Or should I just cut the thread in the straight hole?

thanks

Simon




Srtraight is what it takes.

The tap takes care of the taper.

It's the thread depth which "tapers", not the hole.

HTH,

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."