Friday, 3 December 2010

Finishing, Part2

If anyone asks 'why anglage?' I would have them compare the images towards the end of this post with the one in the header. I think anglage (or bevelled edges), apart from removing burrs, adds a lot to the overall look of the movement. It gives the forms some definition and makes everything look more 'robust'. Also, I quite like the contrast between the straight grained top and the polished bevel. So here's how I do it. I first break the edges with my Swiss escapement files. These are quite expensive but well worth the outlay. These can do in one hour what my other local files can do in a couple of days.

And here you can see the edge has been broken.

Next I sand the filed edge down with wet & dry papers, 3M micro finishing films and lapping films. These are stuck on a brass strip or a toothpick with double sided tape. This helps to get into difficult corners.
.....very time consuming business but worth it.

And below, you can see the fruits of my labours.....
Hope you enjoyed this.


Monday, 22 November 2010

Making a hook for a fusee chain

There have been some posts about watches with fusees on the forums lately. I have a special love for old English fusee driven watches. Most of my vintage collection is full of these old gems (Watches + movements only). Unfortunately almost all of them have some problem or the other. One day I hope to have all of them in good working order.

Anyway, since I have not made much progress on 02, I shall write about a hook I made for an English pocket watch fusee chain some time ago.

This is one of the most adventurous repairs I have carried out so far. It took me several attempts to get it right. The pictures are from several different attempts so they might not 'add up', as it were. But they do tell the story coherently, so here goes.

As I have already stated I only have silver steel in rod form, so the first job is always to prepare a little piece. The idea is to thin down the piece but not so much that filing will bend it.

The next operation is to drill the hole where the chain will be attached. This acts as a good reference point for subsequent shaping. I did not have a bit small enough for this so the only option was to make one. This was easier said than done. I made the bit out of an old needle. All goes like clockwork till the tempering process. The whole thing about making tiny drill bits is the tempering. One almost always tempers too little (so the drill bit is too brittle) or too much (in which case the drill bit is too soft). You will understand what I mean when you see the next picture. It took me 15 attempts to get the temper right. The next day my wife was perplexed by the disappearance of half the needles from the sewing kit :-)

Here is number 15........... and the hole in question.

With that out of the way I could shape the hook part. This hook is for the barrel end. barrel hooks always have the extra horn at the end. The hook at the fusee end has a much simpler shape. I do not quite know the reason for this. Logically, it should not matter which way the chain is mounted in the watch. In fact, some chains I have seen, with older repairs, have had both fusee ends and they work just fine. Perhaps the horn helps the chain to stay upright on the barrel.

The shape of the hook is critical. This is because this hook is attached to a hole in the barrel and carries the entire force of a wound spring. An incorrect profile will only make the hook slip out. Here is the hook with more or less the correct shape.

After this I thinned it down to almost the required thickness. This is done in the usual manner with polishing paper on a glass sheet. Here is the hook with the chain and the broken hook. Please note the rust on the last few links. These were removed, a chain in only as strong as the weakest link :-)
At this stage I tried the hook 'in-situ'. This is important since adjustments are difficult after hardening.
Below you can see the hook after hardening. Any steel part must always be bound when it is hardened. The hardening (heating to cherry red & quenching in water) process invariably distorts the part. Binding wire helps to retain the shape.

Next, the hook must be tempered. It is too brittle directly after hardening. A foolproof method of tempering steel to spring is to boil it out in motor oil.

And here you can see all the parts together. The hook has been cleaned up. The broken hook & rusty links have been removed from the chain & please note the tiny pin that has been filed up for the joint. This pin has a slight taper.
Here is the hook & pin on the chain. The pin needs to be filed down further before it can be riveted.

And here is the hook riveted to the chain.

Looks simple but this exercise took a lot of my time. Of course, I learnt a lot along the way.


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.


Friday, 22 October 2010

skeletonising, Part3

So I have cut out most of the material with a fretsaw. Now the plates and bridges must be filed down with needle files to the required shape. You can see needle files in the picture below.

This is a very delicate task. The part must be held in a vice so that one can file it and yet the vice must not damage the part. Crushing the part, pushing in a steady pin etc. are potential hazards at this stage. Also, filing must be done carefully. Thin areas can be distorted by filing, so these need some sort of support. Any mistake and the watch will not work. This is why skeletonising is more than just sculpture. In the end the watch must work and keep time!

A few days of careful filing results in this, the bridges....

... and the dial plate.
Everything look fine, except ......... please see the next few images...........

As you can see, the flanks of the bridges look terrible. The file gives you the correct shape but the surface that has been filed is quite unsightly.

A few more days of sanding the flanks with emery paper stuck on brass strips and this is what you get.......

..... a nice, even brush finish.

Next, we deal with the inner surfaces. hope you enjoyed this.


Wednesday, 20 October 2010

Skeletonising, Part2

The moment of truth; time to put saw to movement!!!

Well, not quite. Before that I need to transfer the design onto the plates and bridges. I made a template on a polypropylene sheet. This allows me to see through the template (very important if you want to align about two hundred microscopic holes!)
Then I drill holes at all the corners.

Next, I play connect-the-dots with the fretsaw.

This is the beginning of material removal. I leave lots of margin. Even so, the final design is faintly visible at this stage. Here is the dial-plate....

....and the bridges.

There is lots of filing to be done!!!


Saturday, 16 October 2010

Skeletonising, Part1

So after all the preparation and making new parts we come to a not-too-unimportant aspect of making a skeleton watch, Skeletonising :-)

Here is a 'before' picture of the movement
Of course, the movement needs to be disassembled. Here is a picture of only the bridges & plates.

The first thing I do is fix the dial on to the movement. It is important to do this now. The alignment will be difficult once most of the material has been removed. This is the reason why I made all these parts before I touched the movement. in the picture below you can see the dial plate in the movement ring.

Now the dial is placed on this assembly & aligned properly. Markings are made at the 12 & 6 o'clock positions; small diameter holes are drilled; and these holes are broached till the dial markers go through. If you look carefully, you can see the markers in the picture below (sorry for the poor quality image)

Here, I would like to talk about the way dials are mounted on the movement in most watches (including the one that donated this movement). I think it is safe to say that 99 % of watches today have dial feet soldered to the undersides of the dial. These go through holes in the dial plate. Screws in the periphery of the movement press onto the dial feet and hold the dial in place. All ok so far, except that I have seen too many vintage & antique watches with broken dial feet and dials floating about in their cases.

This is the reason why in No.1 I have made the 12 & 6 o'clock markers go through the dial & main-plate. On the other side I will drill a small hole in the dial marker & put a brass taper pin through it to hold the whole assembly together. All will be clear when I actually do it & post pictures.

Anyway, a small problem cropped up. The hole for the 6 o'clock marker was too close to a feature on the edge of the movement. So I had to fill the feature up. You can see the filler ( brass coloured) in the picture below.

This is held in place with a screw. I made the screw out of an old, rejected dial marker. So I am a happy man :-)

In the next post, I will write about actually starting the skeletonising. Perhaps this post should have had a different title :-)


Wednesday, 29 September 2010

The Hands Part3- The Minute Hand

In a skeleton watch the hour hand is held in place by the minute hand. In regular watches the dial does this job. This complicates the design of the minute hand a little bit. What is required is a sort of pipe or collar below the hub to keep the hour wheel engaged with the minute wheel. Hands are also made in two pieces, a turned hub & a thin filed hand. But I wanted the hands for No.1 to have a little more 'meat' on the bones. Therefore these hands are one piece.

As with the hour hand, a hole is drilled & the job is mounted on a turning arbour. But in this case, a sort of 'island is turned at the hub.
The material around this island is filed away.....

..... and the hand is shaped a bit.

Now the protruding collar is turned down a bit.....

... and the inside is turned away to accommodate the cannon pinion.

Here is what the collar looks like.

The hole is broached to fit the cannon pinion.

Now, the hour wheel is 'cleaned up' and hour hand broached for a good fit.

And, finally, a test fitting of the rough hands on the movement.

I can finally begin the skeletonisation. Hope this was interesting.