Making a Bimetallic Balance

Cutting the groove into the face of the steel slug (trapanning).  This groove will receive the brass that will become the outer lamination of the bimetallic balance.

The machined steel slug.  The center bore is left 1mm higher than the groove so that the final crossarm can be a maximum of 1mm thick.  A center hole is drilled prior to dismounting the slug so that it can be centered for subsequent machining on a cement faceplate.

Turning the OD of a brass rod to fit inside the groove of the steel slug.

The finished brass ring side by side with the machined steel slug.

The Brass ring fitted into the groove of the steel slug.

The brass ring has been fused to the steel slug.  In essence, this is a brazing procedure in which the brass ring is melted into the groove.

The slug with the fused brass ring is machined on a cement chuck. The center hole drilled while the slug was initally machined is used to center the work on the cement faceplate.  The slug is faced, the outer wall of the old groove is turned away exposing the brass outer layer.

The brass ring is hammered to compress the grain.  This also work hardens the brass.

Other pictures will follow.  The rest of the process involves drilling and tapping the rim for the timing screws, remounting the slug to finish to size the OD, ID and depth of the floor (to the required thickness of the crossarm).    I will also show the process used for cutting out the cross arm.