Part four - On the Case - by Ramon Wilson

Preparation work for the coming ops consisted of turning two plates to fit the main bores and fitting a false pad in order to take a centre support. The plates are .2mm up on the finished 40mm diameter of the lower case. Not actually required immediately they are there as protection and a guide for the turning.
Then yet another expanding mandrel recycled from previous use.
The top portion below the stubs was brought to the same diameter as that above - 2mm up on 26mm. The parting tool was reground square and a slight groove ground in the front face on the corner of the wheel the corners having a slight radius 'touched on'.
With the top-slide set over at 60 degrees the 26.2 diameter was continued as far as possible toward the stubs.
Leaving the mandrel in the chuck it was transferred to the dividing head on the mill for further work. First off was to face the stubs down to the case diameter on the rear face.
Then removing the waste on the front.
The cases were then set up to have some reference lines scribed on using a sharp boring tool.
Then using an angle plate the stubs were set vertical and the nerve racking process of chipping away free hand to remove as much as possible without stepping over that 'point of no return' began.
Ten minutes or so later with a rotary burr and some hand filing the first corner began to emerge.
Next: fettling. First off was to get everything together - files, burrs marker pen and yes, the ubiquitous cup of tea to steady the nerves.
Constantly applying marker pen keeps a real tab on what's left and instant indication of hitting somewhere you don't want to. Note the tape around the top as protection. This is three layers laid on top of one another and then cut to the width required. A wider band had previously been applied beneath the stubs to protect it from rotary burr over run.
It didn't take as long to get them roughed as anticipated but long enough I guess as the old hands and fingers were soon suffering a smidgeon of age related RSI.

part nine  part ten   part eleven   part twelve