Unknown Tool

[alexblues145]

Found a couple of these tool up from storage,
Does anyone know what they are called or used for, asked a couple of local machinists and no idea.
It has 3 jaws sprung together, but a adjustable slot at the bottom, which I thought might be for a tang at first..

[Isambard]

It is a tapping chuck, for machine tapping. The 3 jaws tighten on the shank, the top sliding part is tightened to the square of the tap.
Could you show a pic of the taper shank side of the head, please? May help identify make.

[tonyfoale]

As Isambard said it is a tap holder. Many tap holders only hold the square part of the tap and that allows radial movement of the tap. The pictured tap holder uses the 3 jaws for a more accurate and rigid fixation and the floating square is used only for driving the tap not for location. I have a couple of those "chucks" on reversing tapping heads.

[thehomeengineer]

Using a friction clutched tapping head for threading bolts/studs etc.Hi
this is an archer tapping head. In my opinion one of the best friction tapping heads ever made. I made a die stock so it could also be used for external threads. There are several sizes of tapping chucks in the range. At the morse taper end there is a nut which tightens down with a c-spanner onto two friction plates and steel washer this clutch is set to drive the tap, but if the tap jams the clutch slips as the spindle rotates and the chuck stops, stopping the tap from breaking. Hope this helps
The home engineer

[alexblues145]

Thanks for the great info, always great to hear they considered good pieces of kit.

No make on the tang I can see but there is some heavy surface rust.

Probably about two years ago that i found these in a draw and have been wondering what they were really for.

Can put them to the test now.

[Isambard]

Archer markings were quite discernible. There were several clones of the chuck...Crown was one, and several Continental makes.