1. Nice piece of work there DM. 2. I need a lathe 3. What was the application for the OP? An RC car or something ?
im assuming grim d means hold a bar in the lathe drill it and tap to m6 that way its concentric irrespective of lathe condition, then wind in the m6 in the cut thread then lock of with a nut drill for the m4 jobs a goodun
Once you have the M6 mounted though it's no sweat to drill and tap an M4, especially in a lathe. I used to frequently drill through 3/16 screws with a 1/8 drill, by hand, with no allowance for breaking through the sides, that's only a gnats whisker over 0.3mm (12 thou) a side on the core diameter. Drilling solid rivets is worse, only a thou or two per side before you break through. I think you underestimate your ability on your lathe! Indeed.
