Sunday, 14 November 2010

Finishing, part1

So we have reached the final stage of work on the plates & bridges. I have decided to carry over the finishes from 01 with some important changes. I want the finishes to emphasise the concept.

The plan for 02 is, straight grained for main surfaces & flanks, spotting/ perlage for inner surfaces and bevelled & polished edges.

The inner surfaces are those that are visible after the bridges have been assembled. I apply the finish only there since I do not wish to affect the end-shakes of the wheels. In the picture below you can see that I have removed machining marks from surfaces I wish to apply perlage on (red arrows). The areas marked with a blue arrow will have a bridge/ cock resting on them. Therefore these have been left untouched.
The machining marks are removed with little brass sanding blocks. These have various grades of polishing paper stuck on them (see below).

So below you can see the movement with the job partially done.

Now, perlage is applied to these cleaned up surfaces. This is done with a rubber bit (charged with an abrasive) on a table drill. I make the bit out of an ordinary pencil eraser. Proper alignment of each subsequent 'spot' or 'pearl' is essential or the job can look quite shabby. Also, the top surfaces are given a straight grained finish. For this, polishing papers of various grades are pasted on a sheet of glass & the job is rubbed on this. The grain is in the direction of the escapement axis.

In the picture below you can see how the different finishes work together.

Next time we will look at bevelling/ anglage.