Making and Using Wax Chucks

Tony Bird demonstrates an unusual but effective method for work holding.

- Tony Bird

Wax mandrels

It is unlikely but possible that the author invented the wax mandrel - certainly he has seen no reference to anything the same or similar.

Their creation and use started with machining of small components that had holes in them, such as big ends, eccentrics and their like. The first photograph shows a length of steel rod that is centred both ends charged with some shellac. On this particular job the centres are not used (photo 27). A connecting rod from a Stuart S50 is mounted on the rod (photo 28). A shoulder is then turned on the big end of the connecting rod (photo 29).

Photograph 30 shows another big end mounted on a stub mandrel. This particular mandrel is useful if the hole is very large; it is made from hexagonal stock so it can be taken out of the chuck and replaced in the same orientation.

The author mostly uses a wax mandrel when machining cylinders. The bronze cylinders in the next couple of photographs that are being machined are for a Blackgates ‘V’ twin oscillating steam engine.

First the cylinders were mounted in a four-jaw chuck and their port face and cylinder ends were machined flat but still well over size. The machined port face was glued to a wax chuck and small faces were machined on the opposite side of the cylinder so that a four-jaw chuck would have something parallel to grip. Alas no photographs were taken at this stage of the operation.