Lay down insert threading tools

[Rickabilly]

I suppose they call them a special name" lay down" as in the old days many of the common threading tips were fitted in holders also used for grooving tools the style that sticks in my mind is the " top notch" if you missed that step in the evolution of threading tips it's pretty easy to figure that we went from normal turning tools to turning tools with a thread form ground into them. In which case the term "lay down" serves only to confuse.
Even when we were using the top notch tools it seemed odd to me that they didn't simply grind threading and grooving forms into normal turning tips. Oh well