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WatchGuy CNC Stuff

Screws

Thread SizePlease choose
ToleranceThis determines the fit of your thread
Mill Diameter [mm]the end mill to cut the shape of the screw
Thread Mill Diameter [mm]the 60 degree thread mill to cut the thread
lead-in length [mm]thinner lead-in before thread starts
thread length [mm]length of threaded part of screw
shoulder height [mm]shoulder for chronograph screws etc.
shoulder diameter [mm]for chronograph screws etc.
head height [mm]height of the screw head. Be generous so you can finish the screw off in the lathe
head diameter [mm]diameter of the screw head
Horizontal Speed [mm/min]about 30mm/min for steel
Vertical step-down [mm]4% mill diameter for steel
Left-handed threadtick to make a left-handed thread
Action

Set-Up

Your round stock is clamped so that it points upwards. Align the mill centred over the stock, and lower the mill slowly until it touches. Set X,Y and Z to 0, and run the code.
When it's time for the tool change, put the thread cutting mill in, and adjust the height of the thread cutting mill so that it sits exactly on the same height as the start of your thread (after the lead-in if you have one). Now set Z to 0, and leave X and Y as they are.
Re-start execution.

I use Kyocera mills.
The thread mills are on page 68. They do cost a fortune I'm afraid.