https://www.cutoutandkeep.net/projects/joining-pieces-of-flat-metal • Posted by The Crowood Press
The first example will explain the general principles of soldering. The edge to edge joint is the weakest of all joints and it is worth considering how you would make this stronger for some applications. For example, a ‘scarf joint’ is when the metal is cut at an angle, allowing a larger surface of the metal to be joined, and a ‘step joint’ is when the ends are cut with two levels, ov e r lapping the edges. These are sometimes only possible with thicker sheets of metal and with practice, as precise work is required. Other options could be considered to strengthen the joint that affect the aesthetics and it is worth considering how the added details will add to the overall design. For example, the edges can completely overlap each other or an extra piece added overlapping both ends; this is often called a ‘strap joint’.
The first example will explain the general principles of soldering. The edge to edge joint is the weakest of all joints and it is worth considering how you would make this stronger for some applications. For example, a ‘scarf joint’ is when the metal is cut at an angle, allowing a larger surface of the metal to be joined, and a ‘step joint’ is when the ends are cut with two levels, ov e r lapping the edges. These are sometimes only possible with thicker sheets of metal and with practice, as precise work is required. Other options could be considered to strengthen the joint that affect the aesthetics and it is worth considering how the added details will add to the overall design. For example, the edges can completely overlap each other or an extra piece added overlapping both ends; this is often called a ‘strap joint’.
Joining pieces of flat metal Scarf joint Step joint Butt joint Lap joint Strap joint Strap joint A variety of joints. Wet or dry the edges. Wash your hands to ensure that the flux or work does not get any gr ease or dirt on them. If needed pin the work to the heat r eflective brick. Flux the joint. Place the solder so it will be easier to clean up later. Heat the work with a bushy flame, if your torch is not adjustable start with it a little further away. Remove the heat when the solder has flowed. Let the work cool before moving it. Then cool completely in water. Place the piece in warmed pickle solution. Remove from pickle when oxides and flux residue have gone. Rinse to remove any traces of pickle. Use a bushy flame Remember the equipment section of this book, which stated ‘the lower flow temperature of the pewter solder will create a weaker bond more like glue’ when using it to solder other metals. A pointy hot flame heats silver solder too fast, creating a similar bond. It causes the solder to flow, but not permeate the surface of both pieces of metal. This may be strong with a little wiggle test but later one piece may break cleanly away from the other.
Ensure the edges that are going to be joined fit together, file them if not. Even a small gap can cause problems when soldering or result in an unsightly flaw. I
f you have filed them then this will also clean any grease and dirt away.
If the edges are flat you may still need to clean them. For this example, wet or dry paper on a flat surface has been used to keep the edges sharp and fitting together well.
Wash your hands to ensure you do not contaminate the flux or work with any grease or dirt for the next stage of the process.
Put the work on the chosen heat reflective surface. Here we are starting simply with a standard heat reflective soldering brick. Pin the pieces if they need to be held in place. This will depend on size, the heavier the pieces the less likely they are to move.
Apply flux to the edges of the metal where it is going to be soldered. For this example borax is used. Borax may bubble and move when first heated, but it will also take a while to burn away, making it a good flux to practise with.
Place a small piece of solder overlapping the joint; take some time to think about this. Consider where would be the easiest place to clean up the solder if it flowed a little in the wrong direction. For this example, the solder is placed at one end of the joint, as it is easier to clean the end of the finished item rather than the middle. Hard solder is used as this is the only joint that is going to be made on this piece.
Heat the metal with a bushy flame; this is known as a reducing flame, which means it is using a lot of fuel and in turn absorbs the oxides that stop the solder flowing. The bushy flame will allow both pieces of metal to be heated at the same time to the same temperature. There is no advantage of heating it up fast with a hotter flame. Apply the heat to the whole piece, moving the flame constantly across the work as if painting the metal with the flame. Use the midpoint of the flame rather than the tip or right up to the torch end and move away a little if the metal is heating up too fast. Remember to heat the metal not the solder; the metal should be able to transfer the heat to the solder. If both pieces are the same temperature the solder will flow along the joint.
Remove the flame when the solder has flowed. If you have a longer join, heat the metal slightly more where you want the solder to flow as it will flow towards the heat.
When the redness of the metal has dulled, cool the work in water. It is advisable not to put hot metal straight into the pickle.
Place your piece in a warmed pickle solution. Remember to use brass, copper, wooden or plastic tweezers as steel may create a reaction in the solution and plate the pieces with a layer of copper.
Remove the metal from the pickle when all the oxides and flux residue have gone. Copper will look a little pink while silver will look white at this stage.
Rinse your work thoroughly. You may want to also scrub it a little with a nylon brush, water and pumice to ensure all the dirt and pickle has been removed.