Thread pitch on Star top punch

I’m trying to find the thread pitch on the Star sizer top punch. Any of you gents have an idea? Thanks in advance.

28 tpi iirc, maybe 27. It’s whichever most lathes won’t cut

It's 27tpi. Fortunately my lathe will cut 27tpi. I believe they picked that weird thread to prevent just anyone from making their own.

I wonder if dies or taps would be available so you don't need a lathe.

Most of the newer lathes I've seen won't cut 27 TPI but lots of the older ones will. My lathe won't so I bought a die for it. https://drillsandcutters.com/1-2-27-...e-die-special/

Shelly

Greetings,

Yes, 1/2-27 UNS.

McMaster Carr sell taps and dies.

By the way, sprinkler heads were Star's main production item. Lots of 27 pitch threads in plumbing parts.

Cheers,

Dave

Dies work very well for cutting the threads for Star punches. My lathe won’t cut the 27 pitch thread.

I elected to have Lathesmith cut me some top punches and whip up 2 dies while he’s at it.

The only thing I’d like to get more than a lathe is a Bridgeport.

Yep, I have two old lathes that will cut 27tpi and a much newer 7x14 that won't. When I get some other things taken care of, I hope to pick up a mill.

I know; old thread but I didn’t want to start a new one. Some of the old Craftsman/Atlas lathes will cut 27 tpi threads. My late model lathe won’t so I bought a 1/2x27 tap and a matching die.

South Bend Heavy 10 with a wide range gear box cuts 27 tpi. There is also a special gear you can add to a South Bend 9A so it will cut 27 tpi.