Spring Cut Off Evolution! An Easy to make design + the PLANS

[CanBeDone]

[QUOTE=Toolmaker51;197288]re post *8. Only limitation seen, won't the extended front will interfere with substantial diameters or mid-point in a bar? Winky's puts the motion above and behind, long the accepted arrangement.
/QUOTE]

Not on my machine, since I consider parting off from a bar of not more than 25 mm diameter. That gives me more than 100 mm free space below the bar to put the toolholder into. But if I needed to frequently part off rings from a 100mm tube, that would be an entirely different kettle of fish.

My key question remains, however: Why does Winky have great success with one toolholder, and when he builds a second one to the same design, why does it fail? Or, to put it in a much broader perspective, Why do we have such a great variety of toolholder designs, not just for parting-off tooling, but also for form tools and even "simple" clean-up operations, and why do so many of them produce poor surface quality cuts? Not under all circumstances, of course, but I experience it again and again, and hear others complaining about it as well. So it is not just my incompetence as a machinist, because sometimes I do produce mirror-like surfaces, but not always. And always is what I want, predictably, whenever I try it.

And Winky's admission of a "Failure" has triggered a chain of thought that might lead to a much better understanding of how to design a toolholder that predictably produces a mirror surface. Last night I had success designing a test rig that I can build given my resources, and that would give me the measurements I need to decide where Winky's builds failed. - That is if I can convince Winky to ship his "Failures" to New Zealand, together with a new toolbit of the same design he uses, so that I can get an idea of what is going on. Obviously, I will reimburse you, Winky.

Another if: to generalize from what works on my lathe to what works on any lathe, I would need access to another lathe, preferably one that is very different in capabilities from my own. Since that would involve physical traveling in a Covid affected world, I would want to restrict this lathe to be somewhere in the Waikato.