Metric reaming

Got to use the new set of metric reamers today to increase the inner diameter of a pully so it can be fixed to the shaft of a lathe motor.   It's provides a very smooth finish and required little effort on my part thanks to the mill's automatic worm feed system. 

The milling machine

Closeup of 8mm reamer

Case Ring

In the runup to SAWTA 4 I have had extra time during preparations, so I have continued work on the brass chronograph case.

I have turned a one inch piece of pvc conduit into a suitable casing ring for the Omega 321.

Now comes the turning of the case.   The main challenge with this is going to get the workpiece centered properly for the final dimensioning.  The 3 and 6 jaw chucks are not suitable for maintaining perfect concentricity.   I will probably have to use a centering scope and the 6 jaw chuck with some shimming to get close enough when working on seperate sides of the case.

Case Progress

Brass Doughnut

Today I took my brass blank, which essentially started as a thick puck of brass.  I then squared off the ends, reduced the diameter a bit and then started hollowing out the middle.  Lots of work to go, but I won't press on with forming the rest of the main case until I finish the casing ring which will decide the final inside dimensions of the case.

Making Case 2

Here is the basic layout for the proposed case.  The outer diameter may have to be reduced to make it easier to install pushers and the stem.  I won't be using this as a engineering guide, but as a proof of concept.

Making Case

 

The Omega Seamaster with the 312 movement I made the minute jumper and hammer springs for last year is lacking a case.  I have overhauled the watch and it's running well, but it's sad to see such a nice movement sit in a plastic tray.  The dial and hands are in okay condition, so I'm going to attempt to turn a brass enclosure for the movement on the lathe and install a case tube and pushers for the operation of the watch.  This will consist for a brass cylinder with a crystal pressed into it, the back will be screw-down with a display back.

So far I've modeled the watch dimensions in CAD and will begin working on the design for the case.  Then the difficult part will be turning the components on a lathe which is really too small for the job.  Stay tuned!

Finished Escapement Model

Finished line draft

Today I finished the CAD version of my escapement.  This was done using Google sketchup.

Drafting

This week we are doing a drafting module in class.  The old Chicago School of Watchmaking program has a 'drawing of the Swiss lever escapement' chapter so we are following the steps outline in that program to complete a reproduction of a standard Swiss lever.  In class I have been working with traditional drafting equipment: pencil, compass, square, protractor, etc. 

However I also have been working with CAD software which makes the process much more accurate and much cleaner.  See the pictures below.

Here is the CAD layout for the escape wheel

CAD escape wheel finished.  Next step is to layout the fork, pallet and roller.