Metalworking Lab Data Recording

Brooch casting

1. At the beginning of the casting process, the wax model and the wax wire supports are placed in a metal form with plaster. The form is then fired as follows: heat up the kiln to 300 F (all temperatures are taken in Fahrenheit), let it sit at that temperature for two hours, increase to 1350 F for a few more hours, then decrease to 1150 F and remove when ready. (this step was done for us). 

2. Rotate the casting machine 2 ½ times and place the pin in before beginning.

3. Weigh out 30 pennyweights of brass pellets and add it to the bowl in the machine for melting metal; place the fired form on the opposite side.

4. Heat the metal with a torch until melted. The torch was a small white/blue flame, but we were unable to get a reading with the temperature gun because it was too small.

5. Once the metal is melted, release the pin and allow the machine to spin and fill the form.

6. When the machine stops spinning, use the metal tongs to remove the form and quench it in a bucket of water. Once the water stops boiling, reach in and remove the form and the brooch. The plaster will have dissolved away.

7. Clip the support wires, then use the belt sander to grind down the stumps. Start with the scotch brite wheel, and then switch wheels to finer and finer grains before polishing.

8. Cut a matching wire down to a little over the diameter of the brooch, and file down the tip to make the pin.

9. Use pliers to bend the non-sharpened part of the pin around the brooch, and file down the opposite side to create a trough for the pin to lie in. 

Sheet metal brooch

1. Use a pick and hammer to tap a hole in the center of a sheet of bronze metal with a hole already punched in the middle. Use a compass to trace a large circle to the edges of the square, and a smaller circle within the larger circle.

2. Use a jewelers saw to cut around the outside of the large circle. Then, remove the blade and thread it through the punched holde to cut the middle circle.

3. File down the circle until smooth using a hand file and/or a machine.

4. Once the brooch is filed, stamp a pattern into it using metal stamps and a hammer. When the brooch warps hammer it flat with a nylon mallet. The brooch can also be curved by hammering the inside with a rubber mallet against a curved metal rod.

5. Drill two small holes into the ring and use the jewelers saw to cut between them to create a hole for the pin, then perform steps 8 and 9 from the casting instructions.

6. Polish and touch up as needed. 

Temperature Data:

All temperatures were taken in Fahrenheit. The entire melting process only took around 2 minutes, and the spinning and quenching process about the same.

Test Initial TempHalfway MeltedMelted
Example test117018232046
Our Test130015572043

The weight of the cast brooch with the wire supports before refining was 50g. The finished brooch was 24g.

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