Everything in a Name...

Yes, that's a marine diesel in the photo, a 1958 Baudouin straight-six of about 7 ½ litres called, predictably, "La Mère Baudouin" (Old Mother Baudouin), all the way from Marseilles. Indirect injection, 3000 kg without the gearbox, about 150 H.P. @ 950 rpm, air
start. She's the prime mover, nay, the very heart, of an old Douarnenez tunnyman which I lived and sailed aboard in 1998, and her unwavering beat rhythmed all our lives.

Naming things is fundamental to their form, and success. If you are called "Fred Bloggs' Typewriter Repair Emporium" you have little chance of being asked to do avant-garde shopfitting, signwriting, asked to repair key-cutting machines or saxophones... For this reason I have usually given my shops and workshops deliberately ambiguous names - in Eire the sign said "The Isoceles* Triangle, makers and menders", and we attracted the most amazing range of work. Naming is also important in the creation a "House", with its colours, fonts, little ways.

We had a nice workshop in Douarnenez, 400 m2 with a roller door and an inspection pit, that had been a "depôt de vins et spiritueux" and still smelled like it. We had a lot of fun, built Mardi Gras floats, windsurf boards, threw some momentous parties; friend SeB called it "Delta Zulu", after the town's call-letters DZ. Later I looked this up, and it means "Vessel (or aircraft) indicated appears to be in distress". Hmm.... mauvaise augure.

In graphics, and to a small degree in web design, I am known as Juliet_Hotel. This comes from an incident at Falmouth in '98. We had taken "Face au Vent" (that's her engine on the photo) from Douarnenez to Cornwall for the summer, and to the "Tall Ships" at Falmouth. Primped and painted, she was superbly appointed that year, and the welcome was wonderful, surely not what we would have seen aboard a yacht. Owner and crew were all retired eccentrics, and apart from a first-time-out butty I took with us, I was by far the youngest. Incorrigibles all; I had never seen 70-year-olds climbing poles to steal flags...

Steaming East into Falmouth at sun-up, about 04.00, I see a small open boat bearing down on us, or at least trying to, and throttle back.
- "Bonjooor" cries the young fellow, "How many are you aboard?"
"Seven!" I shout, and he then throws me across the waves the mother and father of all crabs, snapping and scuttling... I rush to kick the scuppers closed, so the hard-won beast doesn't return to his element, and then another, another... Seven huge crabs for breakfast! I never got that in a Dufour 11. Many Breton fishermen took refuge in Cornwall during the war to avoid the confiscation of their craft, and the ties are still strong. But I digress...

So, we arrive in the afternoon, having been specially invited for Falmouth is twinned with Douarnenez. We pick up a convenient buoy and call on 16, 09, 10, but to no avail. After half an hour the grey Coastguard MTB sweeps by, welcomes us, and hands us a little leaflet; we can stay on the buoy, at £15 a night, but as it's not theirs we might get moved at any time by the owner: anchoring is a mere £7.50, plus the probable cost of a diver to free the hook from the chains, cables and dead babies that litter the bottom in any harbour. Claude, the pasha, is outraged! "Quel accueil!" And it takes us two trips in
the rubber-duck to get ashore. After an evening on the town, where some of the sceptical crew discover for the first time the true merits of flat, tepid, turbid 9º ale from the wood, and Cornish Pasties...

Once more on board, Claude calls "Pare à lancer", "Je lance!"
He's the boss... and we pick our way in against a backdrop of bright lights, amongst the flotilla, to the town, where he has established that there is an old customs quay. Here we can dry out, secure between the wall and one of our "bequilles", which all Bréton boats carry. I put the boy down in the Zodiac, to take the lines, and off we go. This is perfect! We can come and go as we please, talk to the tourists, take on stores and water.

The quay, next to an ancient brick contraband-burning oven known as the "King's Tobacco Pipe", is just under the windows of the harbour-master's office. So, in true FaV stylie I run up the signal
"Juliet Hotel" - "I am aground. I am in no danger." at the crosstrees. As there was no price on the none-too-welcoming leaflet for being run aground, we had nothing to pay. Now, since I have become a bit too old to run up the ratlines with a belaying pin between my teeth, I find this name appropriate.

*Spot the (deliberate) mistake. Two people noticed this in about seven
years, but then I suppose it's a bit subtle, or perhaps they were too
polite to mention it...

Isosceles - from the Greek; Iso; the same, and Skelos; a leg.
Isoceles - with Iso and, from Latin, caeles; skies, heavens.

Thus, an association not of people with two legs both the same, but of
those with the same dream. A wee bit obscure amongst a population many
of whom contented themselves with a vocabulary of 600 words... But I
liked it.

Zünd-Fix Diesel Selbstzünder

Before the days of cellulose acetate, cinematic film was made from celluloid. This sometimes ignited spontaneously in storage, and much more so if it became stuck in the projector, with a naked electric arc inside. Projectionists' cabins were fireproofed, often with a "water curtain" across the door to allow the projectionist to escape without instantly setting the theatre on fire.

Our 1950's Baudouin engines had an ingenious emergency starting system. These engines, as is common in ships, were started by compressed air (30 bar) stored in two big receivers. The air acted, through a special timing-valve, on one of the pistons. Each bottle would start the engine once, so it was "two strikes and you're out". Once the engine caught, this same cylinder acted as a compressor to re-fill the bottles, before receiving a fuel supply and taking up duty as the sixth cylinder.

To start these engines on cold mornings, "cigarette holders", threaded rods nearly a foot long, went from the inlet manifold ramp into each cylinder's compression space. Cotton-wool cylinders, looking for all the world like oversized cigarette ends, were fitted into a hollow space in the inner end of the holder. One end of the cotton (coloured red) has been soaked in Potassium Nitrate, and when heated by the first compression-stroke ignites and serves as an ignition "hot-spot". For some reason the "cigarettes", vital for starting these French engines, are only made in Germany. I imagine the company is old, and small - I have one of the tins, which I treasure, as a tobacco-tin. It is red and yellow - "Zünd-Fix - Diesel Selbstzünder", and inside one can see that it has been made from recuperated tin-plate, printed for peppermint jujubes...

So, if the engine wouldn't start after two tries, not unheard of, there was no more air... Embarrassing at quay, dangerous at sea...The emergency starter was a cylinder about the size of a coffee-mug, which also screwed into the first cylinder's cigarette holder. Inside was put a coiled length of "Special film"; no prizes for guessing, the film had cinema perforations along the edges! With the engine barred over to just-after-top-dead-centre, a percussion cap lit the film, and the hot gasses pushed down the piston and threw over the engine.

Paper Parabolæ

>that we have
at our various warehouses one eight-foot and one sixteen-foot parabolic
mirror. These were made from fiberglass satellite antennas lined with small
plane mirrors >

Yow! Sixteen-foot, that sounds great. You might not bring down aircraft, but in sunshine the focus must get seriously hot. We made much smaller parabolæ from papier maché, and had huge fun with them. We calculated and cut a half-parabola in 10mm ply, and mounted it, along the axis, to pivot on a piece of metal pipe banged into the ground. Piling rocks and stones around it to just clear when the curve was turned round the axis, we covered the mound thus formed with cement and skimmed it off with the wooden form.
Next day the parabolic cement bump was sanded smooth and given a coat or two of gloss paint. When dry, we smoothed aluminium cooking-foil all over, and burnished it down with the back of a spoon. We then built up, over several days, layers of newsprint papier-maché with a dose of PVA wood glue in, and eventually radial "ribs" made from old rope. The resulting dishes, about 45" in diameter, were flexible but surprisingly strong. The kids used them;
- As umbrellas, when it rained...
- As Frisbees, until they got too bent to fly...
- As shields, wash-basins, for collecting blackberries...
And of course for their original purpose: to concentrate sunlight. The focal length was about six feet, and when freshly-made the hot-spot about 2" - 3" wide. Three dishes together, in bright sunshine, would ignite a paraffin-soaked rag as it fell through the combined focus, and our coffee-pot, already as black as night from having been on the open fire, boiled in a very short time. Dangerous? But of course....He He!

I saw two large parabolæ face-to-face across a very large room at the Science Museum in Kensington, London. The foci were shown by loops on metal poles, the idea being that you could talk into one and hear at the other. Worked surprisingly well, across a noisy room. They had some good things there, a part for kids, the "Launch Pad". I remember a bottle-rocket running on a very long loop of curtain track that was impressive too, giant soap films....have a look at DIY on - http://www.sciencemuseum.org.uk/on-line/launchpad/index.asp

Hard and Soft Copper...

Question...

-If you solder stranded copper wire, it loses it's flexibility and
-becomes brittle.
-If you solder solid copper wire, it becomes more flexible, though not as
-much changed as the stranded wire changes.

Copper in (solid) cables is cold-drawn down to diameter through a series of dies. This "work hardens" the metal. Work hardening occurs when a metal is strained beyond the yield point, passing from elastic to plastic deformation. An increasing stress is required to produce additional plastic deformation and the metal apparently becomes stronger and more difficult to deform. Heating the metal "anneals" it, relaxing the stresses within. Copper is thoroughly annealed by bringing it to red heat, but the heat of soldering is sufficient to partially relax the internal stresses.
Most metals will work harden, indeed, the process is commonly used for hardening low-carbon steels that cannot be heat-treated. Planishing Copper and Silver, for example, (as well as making all those little rounds that are so pretty...) renders it so hard and brittle that the work-piece has to be regularly annealed during fabrication, or else it will crack. Another method, used in industry, is "shot peening", where the metal is surface-hardened by blasting it with hard metal beads. Some low-melting point metals, such as Indium, cannot be work-hardened; at room temperature they are already at annealing temperature. Indium is used for vacuum gaskets in fancy lab equipment, because it stays soft. The rest of us get greased leather...

When the strands of flexible flex are soldered they behave as if they were a solid wire; the strands can no longer slide over each other. This will make the assembly stiffer. The biggest problem is at the junction between solid and stranded, and it is here that the wire will break. In sea-going electrical work it is good practice to solder connections and then enclose the join with heat-shrink sleeving to relieve the stress. Good quality sleeving has hot-melt glue inside, which also prevents water from entering the cables by capillarity.

Low melting-point alloys

Alloys of Indium* and Gallium** can be made that melt as low as room temperature. One such alloy is used when grinding glass spectacle lenses to shape. The round "blank" of the chosen dioptric is held on a kind of copying lathe by a cylindrical plug of the alloy which is cast onto the surface of the lens. Wetting the glass, like a solder, this sticks tightly. A shaped plastic pattern, easily adapted with hand-tools to the size and shape of the frame, is mounted on the same shaft, and as pattern and blank turn slowly together a wet diamond grinding wheel shapes the glass. This is fascinating to watch. When the lens is the correct size and shape the pattern prevents it from further touching the grinder. It is then placed in boiling water ; the alloy melts off and is recuperated.

The Optometrist taught me a good trick, which was most useful for replacing odd-shaped watch "glasses". When they had to make lenses for metal frames, they would heat the empty frames and press them onto a piece of Perspex™. This left a mark, which could then be sawn around with a piercing-saw to make the pattern, and kept for reference - they had hundreds...

Many ladies "cocktail" watches had peculiarly-shaped glasses - I've even seen a shamrock / lucky clover. When the glass was lost the watch became useless. Adapting the Optometrist's trick, I found that by pressing the empty watch case onto a thin (1.2mm), warmed sheet of plastic on a cushioned pad, not only would it make the mark but also push the sheet up into a nice curve. Flat glasses look naff, out of place on 50's watches, and often do not leave clearance for the passage of the hands.

* MP 156ºC
**MP 30ºC - melts in your hand, not in your mouth...

Conversations in Horology

Ichabod was the (posthumous) son of Phinehas (1 Samuel 4.21, 14.3), but as usual this OT stuff is a bit obscure.
" Ichabod Crane, the schoolmaster in Washington Irving's classic tale 'The Legend of Sleepy Hollow' is one of the earliest portrayals of a country schoolmaster in U.S. fiction -- and very possibly the best. The tale captures the essence of the town, its inhabitants, and its comic schoolmaster with skill, insight, and humour. "
" Irving most likely borrowed the name from a real-life Ichabod Crane, a soldier from the American Revolutionary War " http://en.wikipedia.org/wiki/Image:Ichabod_crane.jpg

But I digress...

>> No alcohol !
>Please enlighten me. I wasn't considering that, but, why?

Probably not important here (in the Hermle clock), as the ruby bushings are an interference fit in the balance 'staff' tube. Ethanol is a poor solvent for oils and greases, Methanol is more aggressive but rather toxic, attacking the optic nerve (ulp...). The pallet rubies and impulse pin in most watches over 30 years old are held in place with shellac, which is soluble in ethanol. Out of place (in the bottom of the dish), there are probably very few professionals who can put them back again, the shellac being softened by heat to make the sub-millimetric adjustments required.
Watches are usually cleaned, either by hand or in the machine, in proprietary concentrates which are diluted in White Spirit (Turpentine Substitute). I always used one called 'Sony White' (no, not that Sony) which is excellent, and so cheap that I was never curious enough as to its composition to find out how to make it. A good specialist supplier would be able to recommend an American equivalent. However, for clocks...

>What about removing the mainsprings and dunking the whole mvt. in strong
>detergent, then rinsing with distilled or DI water, then baking in a cool
>oven? Lube has to follow *soon*. I know it sounds wacky, but calcs. (and
>Tek. tube 'scopes) were washed. For the record, I don't think that the way
>to do it, but you'll probably have a water-based witch's brew.

You'd be surprised! Let me tell you a tale - in the summer of '95, having lost our house and workshop through an unscrupulous property deal, and being dog-tired myself after running workshop-social-centre-soup-kitchen-rehearsal-rooms-marriage-counselor-library-all-comers-all-hours for many blue moons, I went "on the road" for a summer in the West of Ireland, with just a box of tools. The itinerant clock-mender. I don't know if it could be done now - with the coming of the EU rural Ireland has lost almost all of the innocence which was its very charm.
Typical, and oft-repeated, scenario; I would arrive in a village in the late afternoon. There are a great many bars in Ireland, indeed, small shops often had a "3-stool" bar in the back, where the clients would relax after buying their paraffin, sheep wire and nails... Arrive in the bar, sit, order a pint o' the dark stuff. The 19th Century-stylie toolbox, with brass corners, is noticed. There's always a clock on the wall, most usually what is called there "a Dollar Clock", of American manufacture. I'm sure you are familiar with them - cheap, robust, stamped gears, lantern pinions and open mainsprings, production-line before the Model T, and, 95% of the time, stopped at five minutes to the hour. You would often see several colours around the edges ; the walls were re-painted without ever taking down the clock for fear it would never go again afterwards. A member of the family.

This is iso-8859-1, so you must imagine the accent...

-"That's a fine oul' clock you have there !"
-"Oh God, aye, me Grandfather brought that back from Boston..."
-"Pity it doesn't go though !"
-"Aye, this twenty year..."
-"Well isn't this your lucky day! I've been sent to repair it !"
-"Ah, bejazus, you'll not be takin' it away, now !"
-"Not a bit of it ! I'll do it here, I'll do it now, and the first one in the village is free !"

Now of course your man has nothing to lose. The clock's not going anywhere, it doesn't work anyway, it's not going to cost him anything, and, sure, he's just burning with curiosity. The clock comes down onto a corner table - pendulum, hands, dial... The whole household is there to watch.

-"Have you a saucepan, Missus?"
-"Oh, an old one?"
-"No, the best in the house! And a tea-towel!"

The tightly-wound mainsprings are contained with flat bootlaces, the power let off and the plates are opened. All the wheels and mobiles tumble out onto the cloth, the springs being set aside. Into the saucepan they go with water and some "dish drops", and the whole is set to boil while I finish my pint. The filth and grease of fifty years rise to the top, and are skimmed off. It seems extreme, I mean, who ever would think to boil a clock? But neither brass nor steel are soluble, even in very hot water. Rinsed with a boiling kettle-full, the parts are dry within minutes. The reassembly appears, to the layman, like a act of magic ; he imagines trying to get all those pivots back in their holes at the same time, impossible, but of course we approach the plates at an angle so that the wheels drop into place one by one. Within the half-hour the clock is oiled and back on the wall - leave the dial off for now, you can see its little heart beating away...
Now of course you won't accept any money, but isn't your man a publican? So I sit there all evening for a "feed o' drink", and a meal, and every half hour everyone is reminded, bong !, bong !, that the clock lives again.

-"Sure and it was the quare fellah with the beard an' the hat..."

Almost without exception I would be taken home to a soft bed by someone, so as to have me handy in the morning to fix their clock, and the sewing machine, and sometimes the tractor, and then on to the daughter's, or the aunt's.

Tales from the Bog

Speaking, nay, arguing with "environmentalists" yesterday reminded me of adventures in Ireland when we "mined" peat and restored an otherwise rather barren valley bottom to a much richer diversity of life. I dug out, as it were, some old articles I wrote about these times and if they are not too "off topic", if indeed such a thing exists at HTW, I would be pleased to share them. There's quite a lot, so I will break them up into, I hope, readable chunks. These experiences taught me a great deal about applied ecology, human nature, and minimalist engineering.

Tales from the Bog* (1)


We bought a second-hand Hymac 580B, an hydraulic excavator on caterpillar tracks, for working on the Bog*. It was cheap, being twenty years old, and hadn't had such a hard life having always worked on soft ground. The lads arrived with it on a low-loader, twenty tons of very bright yellow, for it had been re-sprayed. They manoeuvred it down, we shook hands, and they left us standing by the boreen** in the winter morning sunshine.

- “You know how to drive one of these?”, says Charlie. Neither did I, so we started the engine and played with the levers and pedals. The Bog was extensively worked during the war, when no coal could be imported, and the council had built roads, and a bridge. We measured, and although the bridge was just wide enough we were worried that digger would be too heavy for it. Later, when drivers of loaded 30-tonners flew over it we were proved wrong, but then again, they went much faster.

- “Sure, that way ;it wouldn't have time to fall down!”

The only other way in was across the Borlin River, no more than ten feet deep at this time of year. We rigged a high air-intake and exhaust, tanked up, pulled straws, and after lunch were ready to go. Charlie stood on the bridge and took the photos. Driving such a large and ponderous machine for the first time is exciting enough, but how much more so when you are up to your neck in cold, swirling, black water. I was the one with the short straw, of course...

We quickly grew to love our big yellow Hymac, every home should have one. The neighbours soon came to watch.

- “What are ye doing then, Charlie?”

-"Just diggin' a bit o' garden..! "

By nightfall we had a mighty duckpond at the bottom of the yard, and had rooted out patches of brambles that we thought we'd never see the middle of. With the duckpond came the ducks, who seemed quite happy to stay with us - maybe they knew we would never eat something once we'd given it a name. We had hoped that the ducks would keep the kitchen garden free from pests, and they did a pretty good job, but would not eat the slugs; you must admit that they do not look particularly appetising, although I'm sure they are full of protein. We'd read about a 'homeopathic' treatment, and not wanting to use toxic chemicals on the vegetable patches we decided to give it a try:

"Gather as many slugs as you can find. Burn them on a shovel, mix the ashes with water and sprinkle around the beds... This may not work for several months... "

I suppose that this was intended to scare the slugs away, having to crawl on the cremated remains of their kin, but it didn't seem to bother them in the slightest. Where would they have gone, anyway? Having regularly gathered great handfuls of gastropods, we tried feeding them to the ducks. There would be a good solution to the problem - a tireless army patrolling night and day! Alas, the ducks were just not interested, indeed, they preferred to eat the lettuces. Then Charlie has an idea, rolls some slugs in breadcrumbs - and the birds just gobble them up! After a few days they needed no more encouragement, nor indeed any more breadcrumbs, and our problem was solved thereafter.


* Bog - peat bog. Peat, known as "turf" in Ireland, is traditionally used for fuel, and is especially prized in "smokeless zone" cities where burning coal is banned.

Boreen** - small track or road. The suffix -'een' denotes smallness in Gaelic.

Bimetallics - an explosive solution

Harrison's earliest compensations (1750 ?) acted on the effective length of the hairspring, first with a miniature version of his "Harrison's Grid", which is quite common in pendulum clocks, and later with bi-metallic strips such as we would recognise in thermostats today. Pierre Le Roy made the first split bi-metallic balances, at around the same time, and these were used right through the 19th century, until Elinvar was developed in the 1920's by Guillaume.

Bi-metallics can have surprising force. We were once asked to build a ventilation system for greenhouses which were far from power lines, and so had to be autonomous. After a few experiments with fluids, plagued by sealing problems, we tried making stout bi-metals, about two feet long, from steel and brass riveted together. They easily provided enough force to open and close the vents, but after a hundred cycles they started to deform, bulging between the evenly-spaced rivets. Evidently brazing the whole surface would be a better solution, but of course as the first experiment cooled from red-hot it curled itself round into a half-circle! Hmmm...

We found a low-tech solution by riveting the two bars together at one end, with the brass bar slanting upwards at some 30º, coating the upper surface of the brass with lead azide (on top of cellotape, for it reacts with copper) and detonating it from the fixed end. The steel bar rested on a fat piece of boiler plate cast into a concrete pad. The shock-wave at some 18,000 ft/sec surface welded the metals together before they had time to get hot, and impressed the neighbours no end. Kept well greased, they may last forever.

Don't Try This at Home, Kids ! And don't grease your neighbours either...

Regulation

Yes, once elastically invariable alloys for hairsprings had been developed, collectively known as "Elinvars", the temperature compensation, which had been principally to allow for the changing elasticity of the hairspring, became much less important, and un-split ovalising balances, much less fragile, became feasible. There are also balance wheel rims made from laminated Zinc, which expands differently along and across the "grain". Possibly the first compensation system developed (on the wheel itself) was by Breguet, who placed two mercury thermometers on the wheel rim with their expansion tubes running towards the centre (!).
"Anti-magnetic" Elinvars also prevent the spires of the spring from sticking together through becoming magnetised, which could cause the watch to sprint through its day in 14h!

Rate in watches is most commonly adjusted by varying the effective length of the hairspring, this passing between two "curb pins" mounted on a lever concentric with the axis of the wheel. This has both advantages and disadvantages - neither balance nor pendulum are strictly isochronous, smaller amplitudes taking (slightly) less time. By allowing a small amount of play between the curb pins, at lower amplitudes the hairspring behaves, during the time when it passes from one pin to the other, as if it were longer, thus increasing the period to compensate.

In some Chronometers there are smaller screws which, when removed, increase the rate so that the watch runs on Sidereal Time, which is measured by the rotation of the Earth with respect to the fixed stars. Because the Earth moves in its orbit about the Sun, the sidereal day is about 4 min shorter than the solar day. (23h 56m 04.0905s, for the very punctual). This avoids a calculation in astro-navigation, but may mean you turn up early for breakfast. I sailed with Russians who insisted on remaining on Moscow time, French crew who would use their local (+2h in summer) and of course GMT GPS ship's time. What fun, organising watches!

The "Floating Balance"

Ah, sacré Franz Hermle. They never did anything like the others. Sometimes I suspect that this was to get around patent laws ( I will write more on this later, as it is one of my pet rants ), but sometimes they had some very bright ideas. Smiths and Bulova used the floating balance too, but I think it was invented by Blech and Hettich* around 1957.

This is not the same movement, but I suspect the escapement is something similar. -

http://www.hermle-clocks.com/user/engl/start.php4 then go to "Movements" (it's php...)

The "Floating balance" resembles a classic regulator, only it's inside out - instead of pivots turning in jewel holes the holes are mounted in a tubular balance staff which turns on a tightly-stretched wire. This allows the balance wheel to "float", as the name would suggest, and replacement of the wire is much easier than planting new pivots, although still not for the faint of heart (guitar string.**...). A balance wheel in a table clock has many advantages over a pendulum - the clock is transportable, does not need to run level, beats faster so is liable to be more accurate.
However a balance wheel escapement runs best if the wheel axis is vertical - any static imbalance of the wheel will not affect the timekeeping as the spring winds down (and the amplitude diminishes), and there is less friction as the wheel rests on one end pivot, practically a point-contact since said pivot should be nicely rounded, rather than on two line-contacts. The main obstacle to having a vertical-axis balance lies in the fact that the train-wheels are horizontal, and the motive force must be turned through 90º. The contrate gear that achieves this has always and forever been a source of trouble - in classic carriage "5-glaces" clocks the tooth penetration of the contrate wheel into the escape wheel pinion is adjustable, and thus prone to be badly adjusted...
Hermle cleverly gets round this by using the "anchor" of the escapement to turn the corner. The rather crude looking "pin-pallet" escapement is another clever, although much deprecated idea - the impulse faces are on the escape wheel, and the pins are easily replaced (more guitar strings...).
The double-helix (it's life, Jim, but not as we know it) hairspring is to prevent vertical movement of the wheel, one half contracting as the other expands.

Cleaning? Well, get rid of all that oil, for a start ! At least the thing won't have rusted. No alcohol ! I am reluctant to publish "keep out of the reach of children" formulæ on a public site, but if anyone is interested, write to me - I have some great Witches Brews in my cauldron....

More about lubrication in another post - watch this space...

* http://www.clock-museum.co.uk/c191.htm
**No shit! And to get the wire taut enough I mounted the string on an old guitar and "tuned it up" before soldering it in place...

A good idea?

The excentric automatic-winding weights in wristwatches were originally mounted in plain bushings, but these wear and the weight ends up scraping against the plates, or the casing.
Rolex had a "good idea", and pots of money, so they mounted theirs in a stonking ruby. Looks really good, but if you drop the watch hard the ruby breaks into a thousand pieces, while the watch keeps running for up to 30 hours. Aie!
Seiko had a better idea, mounted theirs on a ball-bearing, with the geometrical minimum of 5 balls. And just where did they get a cheap and plentiful supply of 0.7mm tungsten carbide spheres? I'll let you guess, next time you write you probably have one close at hand...

Static Balance

Those bi-metallic balance wheels which were, and are, so pretty but require a steady hand and the patience of several saints to set up properly. As the wheel expands with a rise in temperature the free ends curve inwards, so that the moment of inertia remains constant. If only it were that simple! For a start, the wheel must be statically balanced for in a pocket watch, which may run in a variety of positions, a heavy point would be affected by gravity and act as a pendulum. The wheel is placed with its pivots on two horizontal knife-edges, and when rolled should stop in any position, without preference. (A wheel on an upside-down bicycle will often oscillate before stopping, with the valve at the bottom.) My first, home-made, tool had two razor blades and sat on a sheet of glass, but later I found a real one second-hand, with agate edges.

A real compensation balance has more holes than screws around its circumference. Although these screws have slots they are impossible to move with a screwdriver, no matter how fine, without ruining them - we use a tiny 4-jawed hand chuck which closes by sliding a collar forwards, holding the outside of the screw. It would also be almost impossible to replace the screws if they were not held in this way ; in a lady's 6"' watch they are seriously small...

Soooo... having a statically balaced wheel we mount the hairspring and collet, taking into account the dynamic balance of the whole assembly, for the split collet is not symmetrical. Having "counted" the oscillations against a standard balance and pinned the outer stud in place, mounted the whole in the movement and regulated the watch (in the 5 standard positions, winder-down being ignored for some reason), we can begin to check the temperature compensation. Once the watch is running well at 20ºC it must be placed alternately in an ice-box at 0º, then in the étuve at 35º, and an error curve plotted, sometimes over several weeks.
The nearer the compensation screws are to the moving ends of the wheel-rim, the greater their influence. All changes must be made symmetrically. For finer adjustment, the screws have extremely thin "washers" under their heads, so fine that they cannot be drilled, but are punched from 2/100mm brass shim on a piece of lead sheet.... a labour of Love...

An "officially certified chronometer" must keep time to a minute a month, in the five positions and at from 0 to 35ºC. Ha! Now the nastiest, crappiest dime-store quartz is within a few seconds a month! Tompion and Breguet would turn in their graves....

The fluxgate compass

For many years years the basic instrument for measuring magnetic fields resembled Coulomb's--a magnetic needle suspended at its middle from a fine fiber, or balanced on a needle-point. It was a delicate instrument, of limited accuracy, not suitable for rough handling. Around the time of World War II electronic instruments came into use. One type, now very widely used, is the fluxgate magnetometer, based on the saturation of magnetic materials. A typical electromagnet, such as is used in a relay or machinery, has an iron core around which the current-carrying coil is wound. The coil's magnetic field is greatly strengthened by the iron, because the iron atoms are magnetic.
In ordinary iron, the magnetic axes of its atoms point in random directions, and the sum of their magnetic fields is close to zero. When current flows in the coil, however, its magnetic field lines up the magnetic axes of atoms in the core, and they add their magnetism to the one created by the electric current alone, making it much stronger. But there exists an obvious limit to the process: when all atoms are lined up, a condition known as the saturation magnetization of the iron, the iron core can provide no further help. If one further increases the current in the coil, the magnetic field only increases by the amount due to the electric current itself, with no contribution from the core.
Materials exist - certain ferrites - where saturation occurs abruptly and completely, at a stably defined level. Ferrites are composed of finely divided magnetisable particles suspended in an insulating material, so that no electrical eddy-currents can flow within them. If a large enough alternating current is driven through a coil wrapped around a core of such material, the core's magnetic polarity flip-flops back and forth, and saturation occurs in each half of the cycle, in symmetric fashion. If however such an electromagnet is located in an existing magnetic field, directed (entirely or in part) along the axis of the ferrite core, that symmetry is upset. In the half of the cycle in which the field of the coil is added to the existing magnetization, saturation arrives a bit earlier, because it depends on the total magnetic intensity, external plus that of the coil. In the other half of the cycle, where the magnetization due to the coil opposes that of the existing field, it happens a bit later, because the sum of the two is somewhat weaker than the field of the coil alone. That asymmetry can be sensed electronically, and this is the basis of the operation of the fluxgate magnetometer. Hand-held electronic compasses generally have two sensing coils at right-angles to each other. They are very useful in that they will memorise several bearings, thus avoiding having to try to write them down in the dark or remember them on the way down to the chart-table.

Negawatt* News

Save Negawatts* of energy ! Draught excluders by the yard or metre...
Experimenting on something else, we discovered a curious property of silicon mastic, the stuff you seal around bathtubs and sinks with - although it sticks like dung to a blanket for almost everything, it doesn't stick to masking tape.
Friends had a very draughty house, an old farm, and the door frames and doors were much too irregular to use the self-adhesive foam strips, or the nice everlasting phosphorus-bronze kind sold for the purpose of keeping out the gales.
We stuck masking tape, the pale-yellow paper kind used by careless painters, onto the edges and top of the door and either side of the frame recess, extruded a healthy bead of mastic onto the frame and closed the masked door onto it overnight.
In the morning the door opened easily enough, for the silicone had not stuck to the surface of the tape. We peeled off the tape and cleaned up a bit with a sharp blade and lo, a silicone seal that fitted perfectly into the humps and hollows in the door, which then closed with an ear-popping clunk as in a posh car. Curiously, brown mastic was cheaper than transparent, and you can use white if your doors are painted that colour.
This works for lumpy windows too, of course. I can't include images in list mails, so if you are interested, but aren't sure what to do I've made some explanatory images - write to me and I will forward them.


* Negawatt - large and otherwise expensive unit of energy that you don't use.

simeon@raindropkites.co.uk

Click to enlarge the image.

Project - March 2006.

"Liquid Piston" air compressor with concentric double-acting pneumatic intensifier. The intensifier cylinder is 1m in diameter.

Designed to drive a heat pump for domestic heating and hot water supply, using the spent drive water as the source of low-grade heat. A water source with a head of 30m or more alternately fills and empties the two main compressor drums. As it is the surface of the water that acts as the seal there is no wear or leakage - the loose-fitting wood and foam "false pistons" shown prevent thermal exchange between the drive water and the air above, reduce splashing and actuate the change-over mechanism (not shown) at the end of each stroke. Two conical traps remove condensation from the compessed air. Unless a very large head of water is available, the pressure generated is insufficient to drive an efficient heat pump. Here a pneumatic intensifier increases the primary pressure to over 30bar, permitting the use of carbon dioxide as the high pressure refrigerant medium.
Designed to run continually, with a minimum of maintenance, the installation is intended for domestic or small community use. A cold store or small freezer can easily be adapted as part of the heat source.

Left Hand Thread...

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