This method of making each jaw in two parts seems a sensible way to add the ‘soft jaw’ facility. The curved slots for locating the outer parts would be a complication when making your own soft jaw outers, but once made they could serve for many tasks. And even then, easier than cutting your own scroll teeth.
Why are they only suggested as wood turning chucks? Perhaps because that is Axminsters main business, but is there a technical reason too?
Tim Stevens