Swirly? Tuesday, Nov 22 2011 


Case,  Check

Dial,  Check

Hands, Check

Movement…. not so check.. I can’t put one of the bare non-decorated ETA movements in to this piece, I figure either geneva stripes or a spotted pattern would work nicely.  Having experimented with these patterning methods, I know that I will either have to use an abrasive material impregnated tool, or something like a piece of wood charged with an abrasive like diamond paste or similar, and I do have some silicon polishing bits that should fit the bill nicely.

To do Geneva stripes the movement plates have to be held in a vice that can slide backwards and forwards in  straight line, while applying pressure with the abrasive, for this there are dedicated machines available, though I don’t know if any of these are located in Australia, and I certainly couldn’t get one fast enough anyway.

I had previously experimented doing striping with a large milling machine and discovered that for the best results I needed to be able to control the pressure placed on the abrasive, milling machines don’t do this well.. A drill press would work nicely for this, but I don’t actually have one, not helpful..

I was able to jury rig up a combination of a jewellers hand piece (for drilling etc) attached using a variety of bits and pieces to a dial stamping machine, this machine has a sliding base, with a spring loaded handle to control the pressure, while my foot controls the speed of rotation.. Still not the ideal machine, but should work for one set of plates at least..

Machine of many parts

Machine of many parts

I place the plates where the dial would normally sit and do a few test stripes, but can’t make it all the way across the movement before I run out of room to move.. Unperturbed I turn the dial holding platform allowing me to do circular Cote de Geneve! with a few tests I get a pattern that looks good, and is repeated on the mainplate front and back, and the top of the bridges.

Round and round we go

Round and round we go

Where we stop,

Where we stop,

About here looks good

About here looks good

As the abrasive has ground off the rhodium plating that was coating the movement, leaving it a little messy..

All the bridges, freshly ground, plus a few spare...

All the bridges, freshly ground, plus a few spare...

A quick trip to the platers and it looks all golden and new (well mostly, theres a couple of spots that don’t look 100% but they’re mostly in spots that are not seen)

Freshly plated, ready to put back together

Freshly plated, ready to put back together

The movement is re-assembled and set back to ticking!

All the bits and pieces, ready to make into a watch!

All the bits and pieces, ready to make into a watch!

Balancing Act Thursday, Oct 6 2011 

Now that the majority of the components are playing nicely together, it’s time to get this machine to tick! The most difficult part of this operation is removing the balance from the old bridge, and transferring it to a new bridge without damaging the hairspring or the small parts on the bridge itself.

Part of the reason for this is that ETA now use their own method of holding the balance to the rest of the watch, this is done with a specially shaped stud, held in tension between a “fork” of metal, this in comparison to the traditional method of a cylindrical or semi-cylndrical stud, held in place with a small screw. The ETA method is more efficient in that the height of the stud is set permanently, and is non-adjustable, but usually requires the purchase of specialised (expensive) tools to do otherwise straightforward operations. While my method is definitely not the recommended method, it works most of the time.. With a quick flick of a screwdriver the balance assembly is free from the old bridge.

The components needed are removed from the old bridge and placed on to the new, and not too surprisingly I can already see some issues.. the first being that the seating for the regulator assembly is a little high, which some quick filing fixes. The balance is fitted to the stud holder, (noting that the hairspring will have to be rotated at some point).

I place the complete assembly into the movement, and try and wiggle the balance wheel into position. No amount of cajoling, tapping or swearing works, as the balance wheel is trying to occupy the same space as one of the train wheels.. Not happy..

The options I have at this point are to adjust the position of the train wheels, re-machine all the plates and hope the next iteration has everything in the right place, make a new balance wheel, or fit the rest of the components to the watch (remainder of the winding mechanism), decorate a base 6498 and case that.

The first option was removed from my choices by simply not having the metal needed to complete another full set of plates, combined with the possibility of something still not working and my deadline rushing up..

The second option while briefly attractive, would require some items for my lathe that I don’t own, and some stock material suitable.

The third option it is!  So the things I need to do while reduced is still fairly significant.

Success.. almost… Wednesday, Jul 27 2011 


As I have already determined that I will need to re-machine the plates, I decide to check the escapement components as well, as I don’t want to machine new plates then find problems that I could correct now. The escape wheel won’t be going anywhere, so I focus on the pallet fork and pallet bridge, I am using the pallet bridge directly from the base movement, as it is one part less that I have to machine. I thread the holes for the screws, and fit the bridge, or try to.. the holes for the screws and steady pins do not line up quite right, with some alteration I manage to get the bridge down but the pallet fork is siting at quite an angle, unable to engage with the escape wheel.. Oops.. I figure that by moving the holes for the bridge half a millimetre all will line up nicely and add it to the list of adjustments to be made.

Back to the drawing board….

Determined to get a working movement happening, I return to the computer to check what I’ve done wrong, and to also make some modifications to the design based on my initial observations.

I check the distances that I measured between wheels against those in my computer model, and also the wheel models. I can see (now that I know theres a problem) fairly fast that the wheels are not in the right spot, I adjust the model, moving the 3rd wheel 5/100 of a millimetre, and make sure that the wheel models are now overlapping (representing the teeth meshing together). All appears to be ok, I also add some thickness to the barrel bridge, corrected the placement of the balance bridge components, and adjusted the position of the pallet bridge.

At this point I also make some modifications to the milling program to use a larger milling cutter to do initial cutting (roughing out) followed by a smaller cutter for fine details, in a simulation this will reduce the machining time of the mainplate significantly (from 6 hours to 3) and reduce the chance of breaking the small milling cutter also.

Then back to the milling machine…

I re-machine a complete set of mainplate and bridges (much faster to type than to do) and begin the process of sizing all of the holes and fitting all of the jewels and steady pins again. In my haste I notice (when I go to fit the jewel) that the escape wheel jewel drops though the plate, I check my chart of jewel sizes.. and I’ve read the wrong line.. rather than machine a new plate, I quickly turn a bush to press into the plate that will then have the jewel pressed into it. All good!

I sit the wheels on to the mainplate, and this time everything already seems to be sitting much better..

I fit the train bridge, and wiggle the centre wheel with my finger… The escape wheel spins!!  one part working, just a few to go…

30th December – Start My Engines… Sunday, May 22 2011 

I started machining as soon as possible, a process of around 8 hours solid. only to find that I had gotten confused when translating my measurements to the computer, because of this the recess that holds the barrel was machined too deep, this has the effect of not leaving enough material for the centre wheel jewel to seat into, and also removing some material around the setting mechanism.. Not good!

Re-working the machining file and tooling up, I re-made the mainplate, This time the alignment between the front and back was off by about 0.5mm, as was the next one, so I finally figured out a method of lining the front and back of the plate up a bit more effectively. I had been relying on using locating holes in each plate lining up with matching holes in a perspex machining jig.

Perspex Jig to hold plates

The new method involves moving a tapered point inside holes in the plate, adjusting slightly, moving to the next hole and so on, until the point is in the centre of all of the holes. Using this method I machined a set of both mainplate and bridges, all appearing to line up within about 1/10th of a mm.

Raw Train Bridge

Mainplate with barrel and balance bridges

I enlarged all of the bridge hole to the proper sizes for all of the jewels, and fitted them all, then did the same for the train bridge. As I test fitted the train wheels it became apparent that something was not quite right, the 4th wheel with the extended pivot for the small seconds hand would no longer fit through the jewel.  After a quick modification and removal of the long pivot, the wheel would fit. Success!!  Steady pins were added to the train wheel bridge so that it would locate in the correct place every time, taking a cue from Peter Speake-Marin I made these pins tapered, so that as the bridge is lowered it fits neater than if they had been completely parallel.

Mainplate with train bridge fitted

Short lived success though.. after placing the rest of the wheels in to the plates the first 2 wheels in the train mesh a little tightly and the 3rd and 4th wheel do not touch at all!  and to top everything off, I’ve run out of brass to mill plates out of and most people are closed over Christmas / New Year.. so at least this gives me some time to work on the dial and hands…