KP231, I'll give you a quick-tip you may like.
Make a die stock to go in the tail stock of your lathe. Make it to hold a 1.5" round die.
When you need to thread a metric shank buy class 2 thread dies in the correct spec for the job and it's fast and easy. Just turn the shank to the correct OD and put a 7 degree taper on the leading edge for about 1/16" back. Insert the die and run the tail stock up to the shank and turn the chuck by hand.
Works like a charm and the cost is only the price of the die and about 1 hour in making the die stock I used 2-3/8" bar stock to make my own.
It's very easy.
In some cases you can't get class 2 dies. It's OK to use class 3 or 4, but you'll want to put an 85 degree shoulder on the barrel with looser threads to make it center up better. It does work, and presents not real problems, but always seemed to be a bit "sloppy" to me, so I always try to get class 2 spec dies. Class 1 is too tight and can gaull the action threads, so don't use them. A class 1 thread is a fight to get on and off. If offers nothing to the job and can create problems.
