Bought some unusual threading tools.

[Pete.]

Today I was rummaging in my local used tool & machinery dealer and I found a set of threading tools I had never seen the likes of before - so naturally I had to buy them. I guess we're all familiar with the Armstrong-type threading disc where you can re-grind the cutting edge and turn the disc around in the holder, well these are that type except they are full threadform cutting across two pitches at a time. I managed to snag all 9 pitches from 0.75mm to 3.5mm.

These are a new concept to me. Anyone seen them before? I have to make a holder which should be simple enough but does anyone know what the original holder looks like?

[Ed ke6bnl]

I have one of those lantern style tool holders that takes one of those inserts. I have not tried it yet came with some other tools I purchased. The way I understand it when it gets dull you just grind it flat across the top and it rotates in the holder till it is all used up.

[awemawson]

Same concept, and fore runner to, full form inserts.

[chipenter]

They would make good thread chasors .