morning all,
i need to make a 1/2"-5 (tpi) acme nut 1" long. is there such a tap for this or will i have to grind up a tool and thread cut it?
cheers,
biuw.

there are taps for about anything but they tend to get quite expensive as the thread gets more exotic/less demanded.

try any professional cuttingtoolsupplier if they ain't on stock most of them keep gigantic lists(rather books)of cuttertools.

Use 1/2" X 5 TPI acme thread boring bar with 5 TPI internal acme thread insert.
Consult SECO TOOLS. Seco made one.