Metalwork - Projects - Copper Bowl Candle Holder
This is a nice project which can be used to introduce a few topics other than just Hollowing of Copper. As well as Hollowing the student will also have to learn about Annealing and Soldering. Below is shown an example of the finished project as well as the main parts of the process.
As you work on a metal by hammering, bending or rolling, you are forcing the atoms of the metal closer together thus making it harder and more brittle. Annealing is the name given to the heat treatment process of softening a metal.
To Anneal the Copper you will need a heat source such as a Gas Torch or an Oxy-Acetylene Torch. Observe the usual safety precautions when working with heat sources and hot metals. Heat the Copper Bowl evenly by moving the torch around until it just starts to turn a dull red colour. Using a Gas Torch is easier as is has a much lower heat. With an Oxy-Acetylene Torch you run the danger of burning a hole in your copper.
You can then allow the copper to air cool or you can quench it in water. Either method requires you to be careful as the hot copper will give you a nasty burn !
Step 1 : Physical Cleaning
Using emery paper, clean the surfaces that are to be soldered together.
Step 2 : Chemical Cleaning
Apply liquid Flux to the areas to be soldered together. Flux is a mild metal acid and will chemically clean the metal. Use gloves and be careful as the acid will cause damage to skin and eyes.
Step 3 : Setup
Place and position the pieces you wish to solder in their final positions. Depending on what you are trying to solder this may take a bit of ingenuity using blocks or wire to hold your pieces in place. Remember blocks of metal will act as heat sinks and if you use wire it must be of a type that will not melt ! Blocks of wood or plastic are not a good idea, I hope that's obvious ! Heat resitand blocks and steel wire are good choices.
After setup you may need to apply a little more Flux as the areas to be soldered should be lightly wet with Flux.
Step 4 : Heating
Using a Gas Torch or an Oxy-Acetylene Torch gently heat around the areas to be soldered until the Flux starts to boil away. It is now time to start applying the solder. Keep the heat applied as you apply the solder. The solder will melt and run to the areas where the Flux has chemically cleaned the copper.
Step 5 : Cooling
Allow the joint to air cool.
Tip : Sometimes soldering can be messy, especially when you are new to it as you may be surprised how little solder is needed. One method of reducing the solders flow is to use a pencil and 'colour in' areas where you do not want solder to flow.
The size that you decide to use is totally up to you. Sizes mentioned here are just a guideline and provide for reasonable proportionality. They are also the sizes used in the models on this page.
Design and Expansion
Above is an example of the project in it's simplest form. As there is a huge element of design involved when working with copper there is a lot of room to let students express themselves and expand on the above example and process.
The addition of a handle is reasonably easy either by soldering it to the side or attaching with Copper pop-rivets. All that is needed is a strip of Copper, approximately 20mm in width and 100mm or more long. The strip should then be bent around a suitable sized bar into the desired shape. Bending can be done using a hammer and a block of wood, (to prevent unnecessary damage to the Copper), or if the copper is soft enough just some wood and pressure.
Flaring the Candle Holder tubing can be achieved by using a steel bar that has a larger diameter than the tube. The end of the steel bar should be either chamfered or rounded. Gently hammer the steel bar into the top of the Copper tubing to achieve the desired flare.
There are any number of designs that could be used for the base. Just so long as there is a central portion for soldering the base to the bottom of the copper bowl. With a little imagination the base could be designed to have simple legs. One simple design I saw recently used brass screws and cap nuts through holes in the base to provide an elegant raised platform.
Piercing work can also be used effectively to enhance the appearance of the final product. This is probably a task only for the dedicated as good piercing work is a patient business. The piercing must also be done after the bowl is hollowed, as if it is done beforehand the hammering will ruin the shape of the work. This can mean some very tricky sawing positions but as you can see from the model below, the effect can be quite stunning.
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