An Indexing Quick-Change Toolpost
Introduction Description Construction Toolholders

This view shows the toolpost by itself, with no toolholder.

The large ball handle on top clamps the toolpost onto the topslide.

The dovetail toolholder clamp is operated by the ball handle at the back. This handle has stops that allow about 110° of movement.

The small ball handle operates the spring-loaded indexing plunger by means of a face cam. The indexing plate, fixed to the topslide, provides 24 divisions.

Secondary indexing holes are pitched at 17.5°. In combination with the 15° interval of the indexing plate, a pin placed in one of these holes provides secondary indexing at 2.5° intervals (144 divisions). The five holes have little plugs to prevent swarf dropping in.

In practice, the repeatability is not quite as good as I hoped. I have some ideas for improving it. Meanwhile, I find this toolpost is everything else I hoped for.

The Toolpost in Use
The top left view shows the toolpost set for turning, and the top right for facing.

The bottom left view shows the toolpost set round to 30°, showing the flexibility it offers for awkward jobs. This is useful when clearance is needed for a revolving centre in the tailstock. I have made some angled and extended toolholders to assist with this kind of work.

At the bottom right, the top slide is set to 27.5° for cutting a Whitworth form thread. The index plunger is disengaged (small ball-handle to the right) and, although it is not visible, the secondary, loose, index pin locates the toolpost square-on using the furthest of the five secondary indexing holes.

These views show boring tool holders. The left hand type is for small boring tools, as described by George Thomas. The right hand view shows a holder with a 1/2" boring bar.