Unknown Chuck

Can anyone identify this chuck which I acquired with my Myford S7b.

The end rotates when pulled forward and is abviously intended to hold square shank tools such as reamers or taps. When pushed back towards the main body it seems to engage a 3:1 gearbox.The knurled part is engraved with numbers 1- 4, and there is a register arrow on the main body which does not align with the numbers, and cannot be moved.

Thanks .

Peter

Looks to be an auto-reverse tapping head. Usually used on drills or milling machines. Assuming it is there will be somewhere to fit an anti-rotation stop bar. Holding device at the end should incorporate something to hold the square end of the tap and some sort of adjustable collet or chuck to grip the shank and ensure concentricity. My Pollard built ones have a simple hand operated chuck similar to those on an old fashioned hand powered drill.

In operation the tap will be driven via the reduction gearbox so long as downward pressure is applied keeping the internal clutch engaged. If pressure is released either directly via the drill feed lever or inadvertently by the tap pulling forward too fast drive is lost until the clutch is re-engaged by pushing down again. Upward pressure on the drill feed lever brings the reverse drive into play which spins the tap out at direct drive speed. Settings 1 to 4 are probably overload clutch settings limiting the drive torque so as not to snap taps but still be enough to make a thread. My well be a grub screw to lock the chosen setting or may need to push the knurled ring back up the shaft to clear a key before it will turn.

Archer is a common make of similar style but yours looks too short in the body to be one of theirs.

Clive

Its a tapping head, the knurled ring is the torque setting

Clive

Thanks for the info.

I have now discovered how to adjust the overload clutch. The knurled ring is threaded!

However the device seems to operate in the reverse of your description. That is, when the tap holder is pushed in towards the main body it engages 1:1 drive in both directions. When it is moved away from the body, as would happen when the drill lever pressure is released, the 3:1 gearing engages. I have not risked trying it on a power drive so these observations aRre jus from handling it.

Not shown on the photo, just behind the tap holder and in front of the gearbox is a black ring which has a tapped hole in it through which the tap holder drive shaft can be seen. Have you any idea what its function is, or if something is missing?

Thanks

Peter