Mamod Steam Engines: How To Solder 

Quick Start Instructions:

Soldering a copper to brass (for example).

Clean the join areas with emery paper - if necessary.

Using your mini blow torch, do not heat up the area excessively otherwise you will damage other components and paint unnecessarily.

Use plumbers or electricians type solder and it will need to be in thin rod form.   

Apply plenty of flux paste with a small brush to the two contact areas avoiding getting it on places you do not want the solder to run to (otherwise you'll get too much around there).

Place both surfaces together, heat up both (if they are not already seated together which they can be), apply the solder gently and gingerly to the hot join (not into the flame) causing it to melt and flow and then immediately withdraw the heat.  It will be solid in seconds.

Detailed Instructions:

There is nothing particularly difficult about soldering; it is just a matter of getting the methodology right. Like most things in life, if you don't try it you never will succeed. And when you succeed, practice a bit more and you will be amazed at your results.  So, here we go.

I would like to say at this point that your first attempt may be a complete failure. Please then pick yourself up and try again whilst checking out additional instructions on the internet from places such as Youtube.

Let's say at first that a botched soldering job is a real eye-sore so, as I said, it's as well to get some practice in -

on scrap bits or non-critical jobs. The main fault that is seen (apart from a dry joint caused by using insufficient heat) is an excess of solder used on the joint resulting in it flowing all over the work.

The secret of good soldering is as follows:

• Ensure there is a close-fitting join prior to soldering.
• Making sure the work is CLEAN before starting - break this rule and you will have to do it again.
• Fluxing the work thoroughly (using the right flux: simple, basic paste found in B&Q).
• Using the correct amount of heat - too much and you will soften the metal.
• Using the correct amount of solder (and size of rod) for the job.- try not to get it in places it shouldn't be. 
• Applying the solder at the correct time and place - not into the flame.
• Controlling the flow of the solder - pull it back to reduce the amount being melted .

It is absolutely essential that the joint faces be quite clean and oil-free to obtain a sound joint. The solder will not flow across nor bind to a dirty metal surface. All joint faces should be cleaned with emery and/or wire wool to brighten the metal surface. Always wear eye protection.

Regarding the use of flux. Make sure all joint faces are thoroughly coated and dribble some extra along the joints to make a fillet to be sure. The first application of heat should be gentle to vaporize the water leaving the flux intact; then gradually increase the heat until it melts. The inexperienced will soon discover that you need a surprising amount of heat to make the solder flow.

The first sign that you are nearing the required temperature is when the flux turns to a brown sticky goo; it will change from this appearance to a light-amber mobile liquid as the correct temperature is reached and it will seem to crawl all over the surface of the metal.

When you are sure the right temperature has been reached then move the flame away from the work and just touch the solder rod to the joint, it should immediately melt and flash around - if it doesn't then the work is not hot enough. On NO account should you have the solder rod poking into the flame whilst you are applying heat, not only is it likely to melt and a blob will fall off and stick just where you don't want it, but you are likely to end up with an un-sound joint through lack of heat even when it appears to flow. It is the hot metal that should melt the solder.

Tip:

With fine solder wire, snip a length off and wrap it round a joint before heating; but if you do this put the solder on first and cover it well with flux, then heat the work indirectly - i.e., don't blast the flame at the solder but to one side of the joint. When it's hot enough the solder will melt and flow normally.