Originally Posted by
triumph.1
Just happens I gave it to a friend to try and turn the first couple of threads off with a carbide bit on his lathe. He also has a nicer bench grinder than I which is his last resort. I hope to hear back from him soon. If those options don't work I will have to buy a used cup or set so I can get this built. I am getting anxious to finish the bike.
Why do it the hard way? Turning the thread off means setting up the lathe, fixturing and centering the cup, then turning off the damage. If you take it directly to the bench grinder it's about a 30 second job freehand. You're creating clearance (ie doesn't engage anything) so there's no need for any kind of beautiful job.