After repairing the detached mainspring on my clock I am restoring the case, after 6 years there were a few areas of corrosion starting to appear, and not being able to go sailing I thought I would fill in some time doing that and writing this post.
A 3" 8 day clock, often more suitable for small craft than a 6", Signed by Marpro but a Smith's Calibre 51, 1960s? |
First the warnings:
Do not mess with the hairspring or balance unless you know what you are doing, in which case there is not much point in reading this post! For some reason people seem to think that they can pull or tweak them, I scrapped dozens of pocket watches after people had done that. Adjusting hairsprings and the escapement is a skilled business, damage it and fixing it will likely cost much more than the clock is worth, if it is possible.The motion work of a centre
seconds clock, the inside is more
complicated. If you do take one
to pieces take photos at every
stage to help you when putting it
back together.- Don't mess with the mainspring, if you take it out of the barrel you won't get it back in without the right tools (and if you did manage it there would probably be big isochronism (*) problems due to twisting of the spring), putting a new one is easier as they come pre-wound ready to slide in, but don't bank on being able to do it, take it to someone who does it for a living.
- If taking the movement to pieces ensure it is full wound down before doing so or you will cause significant damage, to be sure put the key on the arbor, hold it and the movement steady and release the "click" (ratchet) and let the rest of the tension off. Like many operations on watches and clocks you could do with three hands doing this.
- Some more modern marine clocks are plated, abrasives may remove the brass.
- If removing the hands take care, the hour & seconds hands, and perhaps the minute hand are a friction fit, levering against the dial is liable to damage the dial. Ideally use a clock makers removable tool or at least use something to protect the dial. When replacing hands, especially the seconds hand do not push it too far on, that can cause friction and stop the clock or make it run short and / or keep bad time. Counter intuitively an escapement that is underpowered, perhaps due to excessive friction in the movement, often runs fast, this is because the balance develops a very shallow and therefore fast action.
- Repainted hands may look worse than worn but clean ones, the exception might be ones that have badly rusted, in that case remove the rust before making a decision, blueing or blacking (in oil) would often be preferable to paint. The exception is the big, usually red, seconds hand on a centre seconds clock, most I have come across have been in poor condition but come up well with red enamel, remove all rust before painting.
- Do not use clock oil on the escapement (The balance (requires it to be removed so not recommended), lever & escape wheel pivots plus the pallet jewels), a platform escapement is about the same size as a pocket watch escapement and needs a light watch oil, a thicker one will likely gum it up. A light clock oil or a heavier watch oil will be OK on the movement pivots.
- On no account spray a movement with WD40 or similar, I have seen that a number of times on pocket watches. It may work in the short term but it will soon cause problems and the residue is difficult to get off unless you have an ultrasonic cleaner. If you have one that it has been done to it will need taking to pieces (except the mainspring barrel) and everything, including the hair spring, needs to be cleaned with a suitable solvent, preferably in an ultrasonic cleaner.
- Do not over oil anything, it will cause as many problems, if not more, than under oiling. Only a small drop is required on pivots. and perhaps a couple of drops of heavier oil into the barrel for the spring but it the clock is running OK leave the mainspring alone. DO NOT put oil on the gear teeth!!
- If someone tells you a non running clock is over wound don't listen to them, they don't know what they are talking about. If you over wind a watch or clock the spring, or possibly the "click", breaks and its pretty obviously not wound.
- Don't try and clean the dial unless you are sure it is cleanable, many have ink printed numbers etc., often on paper or paint and one can run into the other, any attempt to clean one of these is likely to be disastrous and will require it to be replaced, also names may be transfer printed and come off with the slightest touch. I bought in a nice Kelvin Hughes clock where someone had tried to clean the dial, it looks good with the modern replacement dial but it would probably looked better with a slightly mucky original, just harder to sell. Replacement pre printed dials are readily available for £4-£5 but you will have to cut out the holes for everything apart from the centre one.
Regulating the clock
The Glass.
Cleaning a brass case.
Remove the movement, usually just four screws, and put in a safe place.
While I was about it, on this clock I replaced the long broken off opening knob, the remains were drilled out and a piece of brass rod press-fitted and glued in place. |
Ready to degrease. |
Steel Cases
My 7" centre seconds clock in a steel and brass case, restored some years ago with multiple coats of Hammerite gloss black on the steel body. |