Posted by Clive Hartland on 29/11/2021 07:15:37:
Hexagon shaped dies are not used for cutting threads, they are used for cleaning damaged threads.
I've read this many times, but never seen a satisfactory explanation for the distinction. All the hex dies I've seen have a lead-in taper, and, whilst all I've seen have been solid, solid round threading dies appear to be as common as split round ones. In either case, if you prefer a split die and your die is solid it's usually easy enough to make it into a split die. Obviously, in the case of hex dies you have split yourself you would have to use the die in some kind of die holder to make use of the split.
Did the distinction arise, I wonder, not because hex dies can't be used perfectly successfully for cutting new threads, but simply because the intended market for hex dies was originally for areas of industry (such as the automotive trade) where the need for threading tools was mostly for rethreading purposes rather than for cutting new threads and the workers wouldn't necessarily have access to die stocks but they would of course have sockets and spanners?
I note that Machinery's Handbook isn't completely rigid about it, saying hex dies "are intended for repair work".
Edited By Bill Phinn on 29/11/2021 13:04:16