threading 16tpi, half nuts sound wrong at the end

logan 11. 16 tpi. starts fine then the last half inch the half nuts sound like a can of bolts. i back off. first real thread. dont roast me too hard im already nervous. tool is hss. i think its on center. i did not cut a groove at the end

Same family of lathe. Don't ride the half nuts through the shoulder if you didn't cut a relief groove. You're asking them to climb out under load. Pull out at a line you marked, or grind a groove. Also check the tool isn't sticking out a mile. Mine sounded exactly like a can of bolts the first time and it was me, not the gearbox.

What he said. And lock the carriage lock when you're facing, not when you're threading. People mix that up and then blame the gearbox.

If it only happens at the end, look at half-nut engagement before you open the gearbox. Wear shows up when the load spikes. No groove means the load spikes at the end. I'd cut the groove first and listen again.

cut a groove with a parting blade i dont love. sound went away. thread looks like a thread if you squint and then stop squinting. thanks. carriage lock was off. i checked twice because dave will know if i lie