Inserts for every chuck ?

[Allen Neighbors]

I believe inserts were made to adapt, and dedicate, a chuck to a specific spindle thread, but were not made to interchange between chucks all the time. They make it less expensive than having to change entire chucks -- for the manufacturer and for the buyer.
The tolerance of the insert-to-chuck threads is much closer than the tolerance of the insert-to-spindle threads, which is why it's so much harder to screw in an insert, than it is to screw on the insert... Changing inserts every time you mount a chuck on the spindle will take you a lot more time than just spinning off a chuck and spinning on the next one, and will give you greater chance of increasing runout every time, too.
It's best to buy a chuck, buy the insert for your spindle, screw it in as tight as possible, and leave it alone. JMNSHO.

[Nick Mastropietro]

Thanks to all who have responded so far. Based on the feedback, I'm opting for an insert for every chuck, good common sense reasoning when considering the difference between chuck female threads per inch verses headstock spindle male threads per inch. It certainly is easier to start a fastener with a lower TPI than one with a high TPI. It's a lot easier to keep the threads crisp because they are easier to keep clean. I'll consider using the locktite after rinning without it for a while to see if it's absolutely necessary for me. Thanks again - good info from all.