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Auto-Retract Threading Tool


Active Member
Good morning gentlemen, I'm both surprised and pleased to see that my reputation precedes (exceeds?) me.

The auto-retract threading tool came about from a comment about my automatic threading stop.

The commenter complained that it didn't retract the tool as well. Challenge accepted.

The original prototype (the one everyone was complaining about above) was held in a standard AXA toolholder. Shortly after that first video it acquired its own dovetail. It is still the one I use myself. Other comments suggested that they might be marketable, so I made a batch. They sold, so I made another. Those were machined from solid 4140HT, but being lazy (and hoping to reduce the time required) I have modified the design to utilize OTS toolholders. I currently make them in Aloris style AXA, BXA and CXA, with a special order CA in the works. I did make one unit similar to the original for someone who didn't have an Aloris style TP.


Regarding the inserts, these will, of course, utilize any 16ER insert, though a change of anvil/seat/shim may be necessary.

The design is still undergoing refinements as they occur to me. Like everything I design, these things are Stupidly Simple®.
I keep expecting someone to tell me it appeared in Popular Mechanics in 1958.

I have been selling them on several machinist buy and sell groups on FB. I have no experience shipping to Canada, but if anyone is interested I will figure it out.


Ultra Member
I can say I've ever seen anybody attempt a DIY version. The new breed of USB magnifiers kind of fills that role a little bit, but still not quite. I've been tempted to pick one up for a while after seeing various youtubers with them. I wonder if you could combine the magnifier with overlays in a cad software or something similar. That's would be spectacular. I know you could do it statically by saving the picture and importing it into cad that way, but to be able to do it dynamically with help from a stage would be awesome. That is way out of my wheelhouse though.
Everett kinda sorta did


Ultra Member
Yes your picture looks like over-DOC, I see what you mean. Specs for 48 TPI gives a max root flat of 0.0045" (0.11mm) or max root radius if 0.0026" (0.066mm). That's pretty sharp. I don't see that parameter defined on the inserts in Carmex catalog either but I could have sworn I've seen it elsewhere. All I know is I made 40TPI & similar sized metric external threads within their recommended range, stopping DOC when spec pitch diameter attained. They fit commercial nuts & threaded fasteners & parts made from commercial taps perfectly fine. I cant image an insert manufacturer would screw this up leaving customers to have to re-dress them. But I don't have a good explanation. I think there are different flavours 'roughing' or 'partial threaders' ... something like that?

I'm going to have to go back & look at mine. My first impression was, man that looks sharp, I'm going to break it on the first pass. After that I never gave it another thought.
Did you put the insert itself under your magnifier to determine radius/flat as new?
Side note, that website you used to grab your screen shots are my absolute favorite. Thanks