WD40 - The watch's enemy.

click on the image for a larger view

Not for the first time I have had a watch in sprayed with WD40, you can't mistake that smell.

The watch has a 15 jewel Ehrhardt movement - probably a 1906 series but I have yet to take the dial off - it was made for the British Military during WWI  (note the broad arrow property mark below the serial number) but was one of many made by the company that were never delivered and then put into silver cases and sold to the public, this one hallmarked by Ehrhardt in 1921.

It was advertised as "in very good condition and working" and "the watch will run the full length of its wind but does run slow I think it needs a service, the watch sum [sic] time stops I shake it and it starts again".

To get it going someone (possibly not the vendor but I would not bet on that) had sprayed it with the dreaded WD40, it may have run for a short time but on arrival only ran with pressure and it is easy to see why when you look at the hairspring, several coils of which are stuck together. And the stuff will have got all over the place causing other problems.

It should be restorable but will take longer than it should.

WD40 is great stuff - but not on watches!

More on magnetism and watches.

Waltham 1899-Vanguard, 19J, 1902.
(click for a larger view)

A while ago I wrote about how magnetic fields can affect a watch movement, in particular how the coils of the hairspring could end up sticking to each other. This post is about something a bit different.

The Waltham 1899-Vanguard shown here came in barely running (although it was described as "in "good working order") after cleaning, a new mainspring and fixing a number of issues, including replacing a winding pinion that came from a 1908 model that is not compatible with the 1899 and which was causing winding problems, the movement was running with an excellent amplitude (swing of the balance) of 320 degrees.

However when it was put in the case this dropped to an unacceptable 200 degrees and the timekeeping went haywire. When this happens it is normally due to problems caused by compression or distortion of the movement in some way after tightening the case screws, either because of a fault in the movement or by some distortion in the watch case forcing part of the movement parts out of true or causing something to rub. After extensive investigation I could not find anything wrong.

Some degaussing equipment (Demagnetizers) shown on
the Cousinsuk.com web site.

I put the movement in a different watch case and it was fine so I got out the magnetic compass which went wild around the case and the problem was found.

Normally there is a trivial amount of ferrous material in a gold, filled gold or silver watch case, but this is a Hunter, and so it has two large and powerful steel springs in it to flip open the lid and to hold the lid closed. These had clearly become strongly magnetized at some point and that was causing the problem.

A few goes with the degaussing machine and all was resolved.

Whats in beat?

A Swiss lever escapement

If you have ever set up a pendulum clock you will know that it is important to level the movement so that the pendulum swings equally to the right and left of a centre line that is perpendicular to the base of the movement, this will help in timekeeping, make the clock easier to start and, if it is driven by a spring, it will be less likely to stop as the spring gets closer to being fully wound down. It will also result in a nice even "tick - tock". 

It is the same with a watch except that it is now the balance wheel which has to swing an equal amount left and right from it's "in beat" position  - which for a Swiss Lever escapement is when the impulse jewel, balance staff and the lever pallet arbor are in alignment with the movement at rest. Its a little more complicated for an English lever with the pallet tangential to the escape wheel.

 

Before the advent of electro-mechanical and now computerised escapement analysers watch makers and repairers had to adjust  watches to be in beat by visual alignment and listening to the movement through a type of stethoscope, it is impressive how they achieved the accuracy that they did but some errors are fairly easy to detect by listening to the watch.

 

This is my Waltham 1899 Riverside Maximus from 1901, the movement is 0.3 milliseconds (mSec) out of beat which at a nominal rate of 18,000 vibrations per hour (VHP) is an error of 0.17% - that is as close to perfect as you are likely to hear from a 114 year old watch so run the video to see what it sounds like.

 

 

The next video is of  a job in process and the movement is currently out of beat by 2.1 mSec or 10%, run this video and you should notice the arrhythmia.

Correcting an out of beat movement is likely to be a combination of reforming or tweaking the hairspring (in this case it needs major reshaping due to previous tampering and there is a real possibility of work hardening causing the spring to break when adjustments are made), turning the roller or preferably the hairspring collet on the balance staff to improve alignment and possibly some adjustment of the banking for fine tuning.

Watch Faults - Slipping Cannon Pinion.

One in an occasional series on common watch faults.


This is a fairly common fault, particularly after the watch has been disturbed when serviced, usually it comes to light immediately or during the initial test but is can develop after a few months of use.

Symptoms:

The watch runs and the second hand moves but the hour and minute hand do not move at all  (a severe and obvious case!) or pinion slips, and the hands stop occasionally or move slowly giving the impression that the movement is loosing time badly, possibly in a random fashion.


What it is:

The Cannon pinion (left) Connecting to the movement
(under) and to the first part of the motion works which
in turn connects to the setting gear, top right.
Click on the image for a larger view.

The minute hand is mounted on the cannon pinion which also drives the under dial motion gear that moves the hour hand.

The cannon pinion is friction mounted on the central shaft of the watch, this has to be firm enough to turn the hands but has to be loose enough that it will slip when the hands are adjusted either by the key or, in a keyless design, when the setting mechanism turns the motion gear.

The pinion can start slipping if one or more of the following happens:

• Oil migrates onto the shaft - this happens occasionally on unrestored watches when people splash oil all over the place or spray it with WD40 to try and get the watch working.
• The hands rub on the face or crystal putting too much drag on the system for the pinion to hold.
• The setting mechanism does not disengage correctly or the crown is left out on a crown set watch putting too much drag on the system.
• The shaft becomes too smooth for the cannon pinion to grip.
• The pinion becomes worn.
• Some pinions have a cut out and what is essentially an integral spring to maintain pressure on the shaft, this can get weak or break off altogether.

It is thought that setting the watch by turning the hands backwards can cause a cannon pinion to start slipping so only make small adjustments backwards and do so slowly and only if you know that the particular watch will not be damaged in other ways by turning backwards as many complicated watches such as repeaters can be.

The motion gear complete with the hours gear added, the hour
hand attaches to this and the minutes hand attaches to the
Cannon pinion.

How it is fixed:

Usually 2 or more actions are required in addition to degreasing the parts:

• Remove excess drag by sorting out the hands or setting mechanism.
• The shaft is roughened with a file to provide better grip.
• The top of the pinion is bent inwards using a concave punch to make it grip.
• The side of the pinion is nipped in (more) with a special tool (which does not work well on some metals used by English watch makers) or with a hammer and straight edged stake to provide some grip, this is somewhat dangerous as it is easier to over do it and break the pinion or tighten it too much which can result in quite a lot of labour to open it out again.
• Replacing the pinion if one can be found of the correct size.

The dreaded bodged impulse jewel "fix".

Waltham 1908 model Balance
assembly.

A frequently fatal (to the watch) previous repair that I find quite frequently, both recently done to be able to sell a watch and others done many years ago.

Horologists please excuse some simplification and omissions here! Likewise I hope the non-specialist will not be too phased by a little bit of jargon.

What is the impulse jewel?

The impulse jewel is part of the balance wheel assembly, it is a small, often "D" shaped pin like jewel and is mounted on the "roller table".

The picture above right shows the balance assembly from an unrestored Waltham-1908 movement, the roller is the small disk in the centre of the picture with the balance staff (axel) going through its centre and the impulse jewel on the right - it is easier to see if you click on the image for a larger view.


Waltham 1883 movement. The lever
pallet is the dark bar like piece to the left,
the pallet forks are on its right side.
The escape wheel is below it (not quite in
position). This is laid out tangentially  as
an English lever but has a club tooth
escape so is a Swiss Escapement.

As the balance oscillates to-and-fro the impulse jewel contacts the pallet (lever) fork on each swing flipping it from side to side - the "tick" of a watch - this lets the escape wheel at the other end of the lever (on a Swiss escapement) or to its side (English escapement)move on one tooth for each swing and through gears this makes the second hand turn once a minute, the minute hand turn once an hour etc.

By some clever engineering  the impulse jewel also gives the balance a "kick" to keep it moving, it does this twice with every swing on a Swiss Lever escapement with a club tooth escape wheel, once on the unlock and once on the lock) and once every swing with a traditional English Lever escapement with a ratchet type escape wheel.

On an average size 16 or so pocket watch the roller is about 3.5mm / 0.14" in diameter so you can see that the impulse jewel it pretty small. And sometimes they break.

Beware the iPad!

A few weeks ago a customer returned a high quality watch because it was running very fast but when it reached me it was keeping time within a few seconds a day, after a prolonged test I sent it back. It then came back again with the same problem.

This time the watch was still running fast when it reach me and I was able to see that the two outer coils of the hairspring where "stuck" together, when freed the watch was again fine, keeping time to better than 5 seconds a day.

The cause of the problem was  the hairspring becoming magnetised, almost certainly putting the watch too close to the customers iPad, hopefully the watch will be OK when degaussed  - a tricky operation with a hairspring as it will vibrate with the degaussing field.

Don't get paranoid about it, but keep your watch away from computers, power-packs or anything else which might have a strong magnetic field.