New videos online

A series of videos are, at the time of writing, partly uploaded to the SLBBHI youtube channel in which Maurice runs through the process of turning a balance staff on the watchmakers lathe using a hand-held graver.

Part one here:

Not only did Duncan bring along a bench but also also a selection of traditional clock and watchmakers’ turning tools. He started the demonstration by fitting a contrate wheel to an arbor using a beautifully preserved 19th century clockmakers’ throw. 03As the work is held between centres, it is necessary to fit a carrier. Whilst fitting the carrier, Duncan explained that many old clock arbors have a small chamfer turned at each shoulder so that the arbor can be spun between centres without stressing the pivots. He added that the throw has a significant advantage over a chuck lathe as the work can easily be removed for inspection and then put back – safe in the knowledge that the work will be running exactly as before. 04

Once the carrier and the arbor were fitted into place Duncan began to turn the collet for the contrate wheel. Whilst spinning the hand-wheel, Duncan described how he was cutting back a gentle taper to find the right diameter for the wheel, then he repeatedly removed the work to check against the wheel. When the right diameter was achieved he turned the side of the collet straight, removed the work once more and pushed the wheel home. Re-mounted the wheel and arbor between centres and then using a burnisher rubbed over the end of the collet to hold the wheel good and tight. The contrate wheel was then passed around the audience to see the slightly domed burnished collet end that was immovably holding the wheel to the arbor.

Duncan then showed a smaller bow lathe, which he admitted was perhaps not always commercially viable to use in the modern day workshop, but was  nonetheless very enjoyable to own. A tool Duncan employs regularly in his workshop is the modern set of Swiss watchmaker’s turns which formed the next part of his demonstration. Duncan mainly uses these to support components whilst polishing them. He uses various custom made brass runners for this but demonstrated the tuning of a steel spacer.

05 The spacer was mounted to a carrier in the form of a tapered steel arbor with integral pulley wheel. Before fitting the carrier between the centres, he laid the hair of the bow across the bed of the turns. Once the work is fitted he can then simply pull the bow upwards setting the hair on the pulley and by rotating the bow wrap the line tightly around the pulley. He turned the piece, only cutting on the down-stroke of the bow, whilst explaining that he found the small turns very useful for everyday work and used them a lot.06

The final stage of Duncan’s demonstration was to burnish the pivot of an old cylinder assembly on the Jacot tool. He used the balance as a carrier for this procedure and cautioned the audience that it was all too easy to remove material from tiny pivots and it was worth checking progress regularly.

Duncan joked modestly that he should not be trusted with anyone’s watch but the pivot remained intact and gained a bright burnished finish.

07

 

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Mainspring winder with reversible ratchet

James Marten, our glorious leader, took to the bench with a mainspring which had been pulled out of its barrel causing a permanent set. “This is not acceptable” he said, peering over the top of his glasses sternly at the audience and then explained that a mainspring winder could prevent this evil and should be considered an essential bit of kit for any clockmaker’s workshop.

He than produced his mainspring winder, similar to the example illustrated above and a fusee barrel with mainspring inside. Once the cap had been popped off and the mainspring fully wound, James took a pair of short-nosed pliers to grip the end of the spring before removing the barrel – the shorter the nose of the pliers the greater the grip. The spring was kept from unfurling by hand and inspected for sharp edges before being released slowly – during the process being careful to position his body so that he was out of harms way. The spring had a slight set to it and James then demonstrated how it was possible to reduce this by careful systematic bending and corrected the shape so that it would develop inside the barrel with out scraping either end.02

We were then shown a new spring, which was released from its binding, wiped and checked. The first and most important thing was to make sure that the hooking was central and of the right shape. The hooking should, ideally have a flat edge to receive the barrel hook so that it can find its centre inside the barrel and most new mainsprings have oval hole, which prevent this and therefore should be carefully filed to shape -ensuring that no sharp edges are left – and bent so that they readily meet the hook. Once the spring was wound up and fitted to the barrel, the arbor was then fitted and gripping the square with a pair of parallel pliers, James checked to see if it engaged properly with the end of the spring – which it did. The spring was oiled lightly to the tops of the turns, using engine oil, definitely not lacquer (you had to be there) and the cap replaced. The square was then help in the vice and the barrel checked for endshake. James wound up the spring, pausing every now and then to check the endshake. When it was fully wound with equal endshake at every stage, it was allowed to unwind and judged ready for purpose.01

Concluding his demonstration, James explained how to measure a mainspring with a view to replacing it. Using a bench micrometer, he checked its thickness and a ruler to check the height, as well as the barrel’s inside diameter.

James managed to make, what can be quite a terrifying job for the inexperienced workman, look safe and easy – the mark of a true professional!

The first demonstration of the evening was given to us in considerable detail by Ron Rose, who firstly described the equipment required for piercing out intricate designs in brass and other materials, and went on to demonstrate the procedure with great effect.08

A thin metal table with a wedge cut out from it is firmly set up on the work bench to support the job, and a deep throated piercing saw with a round back blade is used. The blades Ron uses are German and can be purchased from Cousins. The choice of blade requires two to three teeth per thickness of work to prevent snagging, and the edge of the metal table can be cut against to reduce the speed of cut when making an intricate manoeuvre. The stroke needs to use the full length of the blade, so there will be constant wear over its whole length, but by using only part of the cutting area it increases wear in a small section and when another part of the blade is used it will grab and break, but lubricant should not be used.

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Now for the demonstration. A pattern is glued and rolled onto the work using a mild adhesive. Ron advises to cut to the line as this reduces filing time. (Try it!!). The saw remains parallel with the arm and does not follow the line of the pattern, as the cutting action remains on the same spot. It is the work that is fed into the blade and on the line as was demonstrated with a circle partially cut out by Ron, and when examined against the light one could not see the point of owning a file. The circle was perfect and without jagged edges.

 

These skills are only mastered over long hours and many years of practise. Ron has been using a piercing saw from the age of fifteen, and has been most generous to share with us some of the lessons he has had to learn the hard way.

Ron received loud and very appreciative applause from the members and guests.

Converting a LINDOW wheel cutting engine to fully automatic indexing and feed

Alan’s talk showed us how to convert a ”LINDOW” wheel cutting engine to fully automatic indexing and feed.

pt265The Lindow is a sturdy machine imported from America by Malcolm Wild it uses conventional indexing and manual feed/return of the cutting tool. This method requires concentration and is open to error especially on unusual and high wheel counts.

Using a couple of recycled stepper motors, some inexpensive toothed belts and wheels, stepper motor drivers and some freely available software Alan was able to convert this machine into a fully automatic and highly accurate wheel cutting engine.10

Alan demonstrated cutting a 29 tooth 0.8 module wheel. Using the software supplied free by Rex Svenson Alan entered the number of teeth and the module, the software calculates wheel diameter and depth of cut the accuracy is shown in this example it showed to be 0.000064” this is so insignificant. The system is a bit on the slow side for commercial use, but this is far outweighed by the fact that you can leave the whole thing to finish the job.

Alan makes all his cutters using the method learnt at a BHI seminar given by Jim Armfield and this along with the REX SVENSON software shows how simply and economically wheels can be cut to a high accuracy.

From the SLBBHI Workshop

londini

We thought it may be interesting to show some of what as been going on in the SLBBHI workshop during the evening classes.

Let me first set the scene. The class is made up of a mixed bag of ‘students’ with a range of abilities including those with many years of prior horological experience, through to myself with almost none. So far, each student brings in their own projects to work on. Each gets individual attention from Ron and, on welcomed occasions, James, with advice on how to proceed, problem solving, associated history, and subtle encouragement for further study. The evenings are frequently punctuated by talks or demonstrations given to the whole class by Ron. Everyone takes an interest in the other students’ projects. In this way the learning opportunities are frequent and cover many aspects. I am looking forward to the next class before I have left the current.

Onward! To describe a project, chosen just because it is mine, and my first ever dabble in the practical aspects of clocks:

The subject is a weight-driven winged lantern clock by Thomas Dyde, Londini, probably dating from around 1660’s. It has been in my family for about 50 years. It has not been cleaned or given much care since it was first restored after being purchased as a box of blackened parts from a shop while on family holiday in Yorkshire. For most of those years it has been running and I have childhood memories: of it’s tick; of watching the pendulum swing in and out of the windows in the wings; and of raising the weight and the pleasing sensation feeling the click while pulling the rope. In recent years it had become tired and would need to take a nap after a few minutes of running. So, it has been temporarily entrusted to me to enliven.

At the start, I had no intention of writing about it so I don’t have any pictures of the initial condition. On first opening the sides it became clear what the probable cause of it’s unreliable performance was: cobwebs and the remains of a diverse range of arthropods. The attention of a 2″ paint brush completed the problem solving but I took the opportunity to dismantle, clean the components with lighter fluid, remove surface rust from the iron components with a fiber-glass pencil, reassemble, and oil. Here are some pictures of the result, with some comments on things I learned, with Ron’s help, along the way.

Lantern Clock

So you can see what I’m talking about, here is the clock, cleaned, and in the sun.

 

 

 

 

 

 

The first point of interest along my journey that I want to share was the minute-hand wheel. The hand sits over the square end. In it’s current state, the hand is held on by a washer and a pin through the steel shaft which the wheel rotated on. However, Ron notes that originally the hand would have been held with a clip that sits in the groove in the square end. The first clue to some changes the clock has seen over the years. The wheel also shows signs that the strike pin has moved and that a tooth has been replaced due to a stress crack that started at the original location of the strike pin. (click pictures for full-size)

minutewheelminutewheelend

Another example of a replacement tooth, and the first I noticed, was not dovetailed as the minute-had repair has been, but instead has a round mortice profile. This is on the wheel that takes the weight (I’m not up to speed on terminology yet, despite being told).

roundmortice

This wheel also shows signs of alterations. The click stop has been upgraded from a latch spring that would have engaged the wheel spokes (and there is considerable wear on these as evidence) and given a ‘stop’ every quarter of a turn of the wheel, to a more fine latch on a new wheel mounted alongside.

 

More on the subject of stress fractures in cast  brass, here is a repair to a crack…

crackrepair

In detail, a stress-relieving stop hole drilled at the end, and a supporting plate riveted in place. It seems that the crack may have been aggravated by a replacement bush:

 

crackclosecrackrepairclose

Someone in the past, who perhaps wanted to avoid riveting a replacement bush in a material prone to cracks, has opted for a more raw blacksmith technique to close up an oversize hole. (By the way, Thomas Dyde had a blacksmith apprenticeship  and was not known to be a member of the Worshipful Company of Clockmakers so in some way this seems appropriate here but probably not generally recommended for fine clock restoration!) The metal around the pivot hole has been ‘moved’ to close up the hole by using a round punch around one section of the perimeter. The punch has been applied to both sides of the hole.

alternativetonewbush

There are more photos available on Google+

The Tale of an Aluminium Tube Or don’t throw it away you might need it

When I was sixteen my father and I bought a Drummond “B” lathe from the swap shop in Croydon. I am now sixty seven and still using the lathe after it came to me upon my father’s death some years ago. Over the years the lathe has had a bed regrind and various modifications including, electronic three phase speed control, a new lead screw and an extended cross slide.

In amongst all the bits and pieces was an aluminium tube about an inch long with markings around it. (See fig 1) Over the years I have considered throwing it in the scrap box as I could never find what it was for.

SONY DSCFig 1

Recently I attended a course at the BHI to learn how to make fly cutters for wheel and pinion cutting. At the course we learnt to make a form cutter and then how to use this to make the fly cutter. This involved using the form tool on the secondary slide set at an angle to cut the blank.

The secondary slide for the Drummond is normally in the cupboard as I do not use it very often. As it was stiff in operation I stripped it and cleaned the thread adjusted out the back lash and considered what set up was required for cutting the blank. During the strip down a plate fell off with a notch on it, I examined it and reconsidered the o ring on the winding shaft. (See fig2)

SONY DSCFig 2

Suddenly the light came on and I realised what the tube was for, found it in the draw, sliding it over the shaft and the o ring. My father had made and fitted an imperial vernier for the lead screw.

Having decided that the pitch of the lead screw was ten to the inch how was I going to measure the feed in millimetres?

I turned up a length of brass to fit the shaft. A tenth of an inch is 2.54mm so using my electronic dividing machine I scribed lines at 7.0866141730 this being 0.05 of a mm. The odd 0.4mm was painted black, so one turn bar the black bit is 2.5mm. (See Fig 3)

SONY DSCFig 3

Rotate the curser round to lose the black bit and I can use the imperial; lead screw to measure mm.  With this device I can measure the feed down to 0.05 of a millimetre. (See Fig 4)

SONY DSCFig 4