This tool is used for making  spherical forms -- such as  balls for use as handle ends --  and it can be used to form a radius. 

As shown below the base has been made to attach to the cross-slide of my lathe.  A round HHS bit is held in a slide that is used to set the radius, and a round handle is provided for pivoting the tool.   


The raw material -- mild steel -- is assembled.

Machining the base   with a fly cutter.  See Article Number 36 for more information on the fly cutter. 

Marking the base, followed by careful  checking to avoid  blunders.

Counter-boring using  a step-drill bit and plenty of cutting oil.  The  heads of the screws  used to secure the side posts to the base fit into the counter-bores. 

All holes of the base are slightly chamfered.

One of the two side posts being milled.  The workpiece was accurately positioned and clamped in the vise.  

Tapping was done using my tapping stand.  See Article Number 12.  Although I am well equipped to do tapping,  it is not one of my favorite activities.  

The side posts are fastened to the base and the based is fastened to the t-slots of the lathe.

At this point, alignment is  verified to assure that the centers of the side posts lie on the lathe spindle axis.  

A pivot shaft being threaded.  The material is free-cutting steel.  See Article Number 2 for information on the Die Holder design.

Rounding the swinging arms.  

Rounding is accomplished by manually rotating the arm while it is pivoted on a pin. 

Slotting the swing arm with 6 mm end mill.  See Article Number 24 for more information on Jack Screws.

A shallow channel is machined on one side of the tool-holder block, followed by machining an identical channel on the other end. 

Making a pivot screw, one of two required.  The screws were made from square bar, held in a fixture in the three-jaw chuck.  The material  is free-cutting steel.

All parts have been made, a very enjoyable moment.

Tool mounted on lathe, with cross-slide positioned to center the tool bit onto the lathe spindle axis.

The starting position is shown for making a ball.  The tool bit is located on the lathe spindle axis, and the tool slide has been adjusted to set the depth of cut.

Testing has been successful.