Mystery Toolholder

Does anyone recognise this little beauty ?

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It appears to be “something like” a Weldon tool-holder, but it’s a bit unusual.

• The bore takes 1/4” diameter as a nice sliding fit, but there are ‘steps’ inside, which stop it entering far.
• The plain clamping area is 3/4”diameter
• The section behind that provides a spring-loaded ejector … pull back and release.

But the stamping on the plain ring at the front reads 6 ISO

So … what style of shank does it take, and what sort of machine would have such a short ‘chuck’ to hold it ?

MichaelG.

Is it s tap holder for a tapping head with a clutch which slips when tsp hits bottom of the hole etc. If so there should be s square drive for the tsp dosn the bore. We had an air driven motor one on a pantograph type arm yo keep the tsp square to the job.

David

The item shown is an Asquith tap collet for use in Asquith tapping chucks, the tap is clamped into the collet buy the side locking screw, as for the stamping 6 ISO denotes the size of tap M6 with an ISO shank, there are various shank sizes available on all taps eg BS 949, ISO, etc The clever part with these collets is the spacing collar at the other end of the collet the thickness of this varies to suit the size of tap M8, 10, 12, etc being thicker M2, 3, 4, 5, all different and thinner the thickness of the collar engages the driving dogs inside of the chuck giving varying degrees of driving force to suit the various tap sizes, the tapping chuck has different settings on the body for Aluminium, Brass, Cast Iron, and Steel, once set at the metal being tapped the chuck will slip at that setting when the tap is bottomed out whatever size of tap is being used without breakage or adjustment, the collets are also available with morse tapers for drilling reaming etc with a much thicker collar at the end giving no slip of the drive clutch, the collar at the end on the tap collets is floating to allow for spindle float when tapping, the collet is driven by the two flats on the shank, used mainly on manual drilling machines collets could be changed without stopping the spindle.

Thank you, David and Colin

… All makes sense now

MichaelG.