Looking for ideas on a threading job that came in last week from one of the larger industrial suppliers of fasteners. A one-off order. Looking for the fastest, easiest, smoothest way to get done quick.
These are 200 x of cylindrical steel nuts, threaded internally M6 x 15 mm long (thru) that need to be given an external thread of M10, all the way. Diameter is now 9.9 mm. No critical tolerances to worry about, just a functional M10.
No prob, right? Just make an external M6 spigot to hold the nuts on while in the lathe chuck, and use a tailstock die holder under power.
Wrong. The torque from the die just turns everthing in the chuck. So, made it out of hex instead. No good. The torque from the die just torqued the M6 spigot right off.
Oookay- maybe single-point cut the thread, and just use the die to clean up? Nope- Tried cutting the thread all in one go, and the result was not good. (infeed 1.5 mm) So, two cuts then. Nope, still no good. Three cuts?
No, this is getting out of hand- this is a 200 x job. Three cuts per, means six hundred stops, goes, revs and infeeds and die chases. NO WAY. NO. Will NOT do. I want this done in the easiest fastest way.
Thought about using those three-pointed (well, 2Â½-pointed then) carbide inserts, thought about making a 60* multi-cutter to drive in the toolpost grinder, or an old tap, thought about using an old die cut in half as a one-pass tool...
Seriously, this is the esiest job I've had in years. Question is, what is the most effective way to go about it?