Feet soldering technique using the Rose’s metal alloy
Let’s look at a simple and useful technique of repairing broken dial feet. If one of the feet is broken, a known method used by some watchmakers is putting a plate on a piece of double-sided tape. This is a bad method, though, and you should not do so, as soldering the feet back on is so much simpler and a lot more practical!
In the following review, we will be using the Rose’s metal alloy (25% Tin, 25% Lead, 50% Bismuth), its melting point is just 94 degrees. Such a low temperature guarantees that the enamel will be safe during the process.
The technology is based on heating the dial plate, so it can only be used for older enamel (ceramic) dials, while today varnish/lacquer watch faces can easily be damaged with heating.
1. The photo shows us a broken dial foot, a very common problem.
To begin with, let’s draw a cross with a marker, which will help us get the starting foot position before the process of taking the older soldier off.
The enamel dial foot is broken
Using a drill and a thin diamond disk, we take off the counter-enamel from the copper underside. Do add water, as this helps cool it down, dont’t press too hard as well.
A hard vibration that the disk makes can be very dangerous to the enamel, as this might crack it. Take a precisely centered disk, as thin and soft available.
There is a leak of counter-enamel around the foot, so it will take some time to take it off. It is very normal at the current stage, thus you must not hurry. It is very important to not damage it.
2. After cleaning a 3×3 mm space witht the diamond disk, let’s put a drop of soldering acid and some Rose’s alloy there.
Process of enamel dial soldering
Next we will need to heat up the plate thoroughly and evenly, until the alloy is melted by the heat. The alloy does not need to have a flame on it, it will soon naturally melt and turn into a drop, but will not spread all over the place, we will need larger surface area, though.
3. The alloy is stuck to the plate, it will spread itself round.
If a round drop with shiny sides becomes the outcome, it will easily fall off.
You need to ensure it is spread like so, as this is very important.
4. Take a brass rod of correct thickness, pre-tin it, and bend as shown in the photo.
Holding onto the longer part, we push another stick against where the older foot stood (here, we will need the cross we drew).
The rod is to be soldered using a thin soldering iron, the hot point moves to the needed position.
It is very important to get it very perpendicular and get it right into the cross center, otherwise the watch face will shift and so will the second dial, which will jam the second dial shaft.
repairing the enamel dial foot
The watch face is stuck onto a cork plate (wood, etc. would work as well) using paper tape.
5. Use pliers to cut the soldiered foot to the length needed.
The foot must not be bent!
If the foot needs to be moved aside or rotated – the following operations from step 4 must be repeated.
The foot must not be bent, as the contact area is large, soldiering is strong and the counter-enamel protection is missing.
Bending it will move the front plate, and cracks could appear on the front, or even bits of enamel could fall off.
6. The front of the dial is ideal as before. The temperature is too low, 120-150 degrees will not even affect the enamel.
(let’s confirm again the fact that this method s not to be used with varnish dials)
If the enamel has tiny micro-cracks or spider webs, they can grow bigger or darken on stage 2.
7. Use a thin file to cut under the watch dial screw.
Traditionally, a plate would include space around the foot for a few drops of soldier to fit around it, but sometimes it requites to cut the extras around the foot, such is easily done with a scalpel.
If you are going to repeat the following technology, please try it on a few sacrificial useless dials.
When you get the technique, the whole operation will, at most, take 30 minutes.