Exam

This week was the 3rd of our intermediate exams. The Geartrain. 

Up to this point we’re only concerned with everything from the barrel to the escape wheel (so not the pallets/balance assembly).

The exam itself involved working once again with the ETA 6498. We were each given a brand new movement that had faults introduced to it by the instructor (each watch had the same faults). First up was to assess the movement condition plus the condition of the supplied dial, hands and case. 

Then the exam proper started. Careful disassembly of the movement revealed bent 3rd & 4th wheels, displaced jewels in the train bridge and a burred hole in the barrel cap. Crack on!

First up, straighten the wheels. This is done by holding the wheel in a Trupoise tool to assess its shape and pushing with peg wood to remove any bend. I have to say, the result was very good. I managed to get both wheels spot on. It’s worth noting that industry pressures would now probably require a bent wheel to simply be replaced on a modern watch but that may not be an option for a vintage piece with limited parts supply. Wheel trueing is a handy skill to have. 

Next up, now I’m working with true wheels, it’s time to set the end shakes of the wheels. Horia tool this time to push the train bridge jewels into their correct position. For the purpose of the exam, we start at the escape wheel and adjust to give 0.02mm of endshake. Then it’s on to the 4th wheel, 3rd wheel and centre wheel to give 0.03, 0.04 and 0.05mm respectively. Again, I’m not at all bad at this bit so I was pleased with the result.

That’s the first key stage done, replace the damaged barrel cap and throw the lot in the cleaner. Time for a coffee. 

Reassembly is then just a repeat of the process we’ve practiced a hundred times. Correct oiling of the keyless works and gear train, proper tightening of screws, etc

Movement reassembled, it needs the dial and hands on. In itself this isn’t difficult, it just requires care to avoid marking any components and to ensure the hands are precisely positioned. Black dials and shiny, polished hands show every mark and speck of dust!!

Casing up has always been a bit of an issue for me, not least because we don’t work in a true clean room. The number of times I’ve pushed a bezel and crystal on to spot a rogue speck of dust laughing at me from the dial! Things seemed to go ok this time (unless I missed something!) so then it was just a case of trimming the winding stem to length and fitting the crown. 

Although it’s not controlled in this exam, good practice dictates regulating the watch so it’s on to the timing machine. Good numbers show I can’t have done a bad job!

On with the case back, pressure test, final polish and then wind and set to time before handing it in. Job done

Just the minor issue of getting it marked now…..

Advertisements

More servicing 

We’re on the road to our next exam, Geartrain Servicing, on 7th June. That means one mock exam per week and practice, practice, practice. Straightening bent wheels, setting jewels to give the correct end-shake, cleaning, oiling and assembling. 


It’s repetitive but that’s the point. I’m getting better at judging oil volume and placement, especially on the escapement. 

I’m getting better at judging jewel settings. 

I’m getting better at fault-finding. 

I’m getting better. 

Service!

Back to servicing. 

Started this week with a quick refresher servicing the ETA 6498 to get back into oiling, etc after burnishing and polishing. 

Then it was an introduction to the last couple of skills we need for the upcoming gear train exam. First of all we had to learn how to adjust the tightness of the cannon pinion. This is extremely important as this pinion acts as a slipping clutch, holding the minute hand during normal running and slipping around the centre wheel arbor when setting the time. 


Adjusting the cannon pinion is a fairly primitive procedure for such a precise operation. Tightening involves placing the pinion between two chisel-shaped jaws and hitting the top one with a hammer to pinch the pinion. Loosening involves broaching it out from the inside. It’s tricky but possible. I proved it!

Secondly, we learned the methods used to precisely shorten the winding stem and then fix and true the crown. Strong side cutters and an India stone sort the stem out, a leather mallet takes care of the crown. 

Those tasks completed successfully, we had our first mock exam on the gear train. We each received a brand new movement, case, dial, hands and crown. One of the instructors had previously bent wheels and misaligned jewels in the movement. The exam set an 8 hour time limit to disassemble the movement, correct any faults, clean, lubricate and assemble the movement and then fit dial and hands, case up and fit the crown and stem. The first time I had ever carried out the complete procedure. 

I’m pleased to say, I passed with flying colours. A few things to be improved upon but that’s what mock exams are for. 

A very productive week and one that I thoroughly enjoyed. I could do this for a living! 

You can’t polish a…

Time to do some more work on the WOSTEP WO1 watch. We’ve made the winding stem and balance staff, now we need to work on the bridges.

The bridges are supplied machine-finished which means they’ll work fine but don’t look great. It’s hand-finishing which separates the mediocre and the functional from the great and the beautiful.

The first step is to flatten the upper and lower surfaces on paper. This improves the appearance by leaving a grained finish but (more importantly) ensures the surface is flat. The aesthetics can be further improved later but you need to start work with a level playing field.

Next is flattening the sides. Trickier as it’s vital to retain the sharp corners to give the best appearance. For this we use a piece of brass bar, faced off at each end in the lathe so as to ensure the ends are flat and at 90 degrees to the sides. Placing the work piece on the bench, you can then wrap paper around the brass and carefully work the flanks to the same grained finish as the upper and lower surfaces.

Once the sides and uppers are free from machine marks, the next step is to polish the countersinks in the screw holes and jewel holes. A circular cutter is used to give a consistent finish and then a piece of peg wood is shaped so that it matches the shape of the countersinks. The peg wood is then mounted in the lathe and diamond polishing paste applied. After that, you just push the peg wood into the countersinks and – voila – a polished finish.

Finger cots stop you touching the work piece with your skin. Grease and acid on the surface of the skin will tarnish German silver in hours. A finger print can permanently etch itself into the metal if left!

Something different 

Things relaxed a little on the run up to the Easter break which gave the opportunity for the class to work on our choice of side projects. Some elected to make tools, others chose to work on their school project watch. A couple of us had watches of our own that needed a little tlc. 

I decided to service my Smiths 1215, acquired from eBay last year. Sadly neglected and a little worse for wear, I’d stuck it on a strap and put it to one side until a time like this. 


The watch is historically significant as, apart from being English made (something which is of huge appeal to me), a slightly modified version of this model was supplied to Edmund Hillary’s 1953 Everest expedition. Smiths watches were the first on the summit of the highest mountain on Earth.

After stripping it down, a couple of issues became apparent. Firstly, the setting lever spring had snapped. This isn’t a big problem, they’re still made for this movement and not at all expensive. 


Secondly, the mainspring had set. Instead of springing into a nice long ‘S’ shape when removed from the barrel, it stayed tightly coiled. The watch would still tick but the duration of run would be terrible. 


Again, no big deal as replacements are available. In addition, I’m going to replace the crystal. As is common on watches of this type and age, the ‘crystal’ is a dome of plexiglass or acrylic and is really prone to scratching. Replacing it will freshen things up and allow a clear view of the dial which has aged very nicely. 

The whole thing has now been through the cleaner and will be lubricated and reassembled when the new parts arrive. Something to look forward to. 

Black gold, Texas tea….

I’m talking oil. Specifically which oil, how much and EXACTLY where it needs to go. 

After much dry stripping and reassembling of the 6498, it’s time to start oiling. First things first, oiling the shock settings that support either end of the balance staff. 


To get the practice in without having to keep cleaning the watch, we use a plate with 20 incabloc settings mounted in it. After setting the jewels at the right height, the task is to apply a precise quantity of oil dead centre on the ruby end-cap and then mount the ruby into its setting. After a few practice runs under the tutor’s supervision, we have to implement our own quality control. Oil all 20 jewels perfectly and submit them for inspection. Any mistake on any one of the settings gets the plate dunked in alcohol so the whole lot has to go into the cleaning machine to be started again. Complete the whole plate successfully 5 times and you’re done! 100 jewels straight with no mistakes sure gets your eye in!

Then it’s on to servicing the whole movement. Stripping, cleaning, lubricating and reassembling the keyless work, train and escapement. 

Repetition, repetition, repetition. I invested in a finer oiling needle than those supplied in our school toolkit and moved to working under a 30x microscope. Accurate placing is so much easier than trying with an eye glass in. 

I’m getting better with practice but could still do with a little more finesse, especially on the escape wheel teeth. Pushing a ‘needle’ with a bead of oil on the tip into a watch movement and ensuring that oil only ends up in the intended place is an acquired skill. I need a few more goes yet. 

White coats time

So micro-mechanics is done with (from an exam point of view). Amongst other things, that means a move from wearing dark blue coats at our benches to crisp, new white coats. Our classroom just officially became a clean room. 

It’s time to start servicing watches. Specifically, the ETA 6498. A big old clunker that would be familiar to Panerai owners (or not). 


Straightforward, easy to work on and perfect for a load of beginners to get stuck into. First things first, take it apart….


Then put it back together again. Then take it apart again. Now put it back together…you can see how this goes. Repetition, repetition, repetition, practice, practice, practice. This is exactly what I signed up for and I love it. 

So you think you can turn?

Winding stem? Easy! What ya got next?

Balance staffs….

They make winding stems look like rolls of carpet. 


A few millimetres long, a couple of millimetres at their widest point, steps, gradients, undercuts and conical pivots burnished to a perfect finish. How hard can it be?


Plenty hard. That’s how hard. 

In fairness, the turning is just progression of the skills practiced on winding stems. The dimensions and tolerances are smaller but the principles remain the same. Rotate a piece of metal in a lathe and use another piece of metal to cut bits off it until it’s the right shape. 

Burnishing I had a real problem with at first. Turning removes metal, burnishing rubs a harder piece of metal on to your work piece in order to compress the surface, making a stronger, smoother ‘skin’. In this case to reduce friction as the pivot rotates in the jewel. 

I spent 2 weeks achieving nothing but snapped pivots. Persistence pays off but we’re all human and the frustration began to build as my classmates all appeared to be progressing with relative ease. 

Then it clicked. It wasn’t the technique I was struggling with, I simply hadn’t found ‘the feel’. I had been misinterpreting just what burnishing should feel like through the fingertips. I had been chasing a smooth, rolling sensation. Whenever I found that, the balance staff would shift in its runner and either no progress would be made or the pivot would snap.

Then I found a slightly rougher sensation as I passed the burnisher across the pivot. Instantly I was getting results. Results that I could consistently reproduce! I’d cracked it and never looked back. 

I must stress that my inability to progress does not reflect badly on my tutors. They gave me guidance and suggestions at every stage but micro-mechanics at this level is very much about finding your own technique and ‘feel’. It’s about practicing, making mistakes, systematically correcting and making breakthroughs. 


In February I passed my balance staff exam. 2 exams done, 2 exams passed, no resits required and the micro-mechanics portion of the course boxed off. 

I’m not too bad at this lark. 

Catching up 

I’ll admit it! In so many ways I’m impulsive but, equally, I’m a procrastinator par excellence. 

I’ll update this blog tomorrow, this weekend, at the end of this month….and here we are. Time to take up the quill again and fill in some gaps. 

The last time I was here, I was learning how to make winding stems by hand, with a view to passing my first exam. The stems got more complicated, the tolerances got smaller and my skills improved to the point where, I’m pleased to say, I passed! Chalk it up. 


And there it is. Precision made on a hand lathe to tolerances of a few microns. Doesn’t look like much does it? I consider it quite the achievement for somebody who hadn’t looked at a lathe in the 30 years since high school. I’m on my way to calling myself a watchmaker

Stems and squares

As you might have gathered, the last few weeks (and the next few) are all geared towards acquiring the skills to make a winding stem.

The first part of this week I finished the latest marked project, a dummy winding stem with shoulders and a thread but no square or slot.


I handed it in knowing it wasn’t perfect but making the informed decision that restarting may not be the best use of my time.

As expected, the piece did achieve a lower mark than my previous projects but comfortably achieved a pass. I was pleased with that. Now don’t get me wrong, I’m something of a perfectionist and would have preferred a top mark but part of my learning process on the WoSTEP course is recognising progress. My lifetime experience of turning on a lathe amounts to the last 3 1/2 weeks or so. I’m getting better. I’ll get much better!

In fairness, the quality of my turning is good, I just seem to have trouble with using the measuring equipment which means I’m getting inconsistent lengths within the piece. More practice required then.

Having handed the stem in, it was time for another new skill. This time we’re turning bars down to a specific diameter (precisely, no tolerances!) and then filing a given length down to a perfectly centred square section.


As with everything, it’s a case of slow and steady, look after your tools and measure regularly. Very regularly. No margin for error now!