Soldering in Clockmaking

Soldering involves the joining of metal under heat. Solders are commonly divided into two general groups, known as hard and soft solders. The hard solder fuse only at a red heat and the soft solder fuse at lower degrees of heat.

Four general rules for successful soldering are:
1. absolute cleanliness of the parts
2. equal heating of parts being joined
3. a pure flux
4. a solder of the proper alloy

Possible heat sources are propane, natural gas, acetylene, oxy-acetylene, water torch, lamps, and irons.
Solder is made up of alloys of two or more metals and there is a wide variety. Soft solder is made up mostly of lead and tin. Generally the higher the percentage of tin the lower the melting point. For soft soldering, where temperatures of around 500 degrees F will be required, electric soldering irons will usually do the job. The major drawback of  a soldering iron in clock repair is that they must be brought into direct contact with the parts to be joined. This is sometimes difficult without dislocating the parts.

A soldering flux is a liquid, solid or gaseous material, which when heated is capable of promoting or accelerating the wetting of metal with solder.

There are some basic principles of soldering in Clockmaking.
1. Solder is not a cure-all and should never be used as a filler. Careful fitting, leaving as little area as possible to be filled by solder will produce the strongest joint.
2. Clean surfaces
3. Support each part so they will not move before the solder flows and cools.
4. Always apply flux
5. Never apply heat directly to the solder, heat should be directed to the parts to be joined.
6. Use as little solder as possible, all that is necessary to fill the joint.
7. Allow solder to cool before moving.
8. Remove excess solder

Soldering is an art, so practice makes perfect. I do not do a lot of soldering which is good in clock work but it also means I have not perfected the art of soldering.