Craftsmanship Improvement Method
Craftsmanship Improvement Method is a method to reduce technical problems which one repeatedly experiences. We all find during the learning process that there are times when the same problem presents itself over and over again.
Sometimes when beginning one overworks pieces to death in attempts to effect repairs, getting ever deeper into a mess by trying to fix the mistakes, rather like when I was learning to cook and I made about a gallon of completely inedible curry starting with a small pot full. All attempts to rework it failed leaving me with a lot of horrible food.
This is a method to reduce technical problems which one repeatedly experienes. We all find during the learning process that there are times when the same problem presents itself over and over again. Sometimes when beginning one overworks pieces to death in attempts to effect repairs, getting ever deeper into a mess by trying to fix the mistakes, rather like when I was learning to cook and I made about a gallon of completely inedible curry starting with a small pot full. All attempts to rework it failed leaving me with a lot of horrible food.
All this thinking and writing is so much work that the next time one is about to make the same mistake one remembers this and so avoids the problem and breaks the repetitive circle.
It also offers a way of successfully approaching technical problems one has not encountered before and improves one’s understanding of the material.
The steps may be summed up as:
If working in a group give yourselves a time limit to the discussion at each stage.
- List (choose most appropriate solution)
- Identify the defect or problem in the work.
- List as many repair options as one can think of, even ridiculous ones. Include “sending it out for someone else to do”.
- Identify the point in time when the problem occurred.
- Identify the cause of the problem at that point in time. If you have to call people and ask for the reasons do so. Also this may require some reading. In a group some semblance of an answer can usually be figured out.
- List ways of avoiding the problem at the moment when it occurred. All of them, as wide ranging as you can think of including sending it out.
- Choose the most appropriate solution for the particular piece and choose that solution next time it occurs.
- Identify and list the indicators of the problem’s occurrence so that it may be recognized before it happens in the future.
- Identify defect or problem in the work. e.g. Pits throughout a silver cast piece.
- List repair options.
- planish surface closed, emery, polish lightly.
- file flat, solder sheet on surface, finish.
- emery, polish till below pit level – this probably won’t work.
- flood surface with solder – will not work.
- texture entire surface to make pits part of design.
- fuse surface lightly with hot flame and refinish – this is rather difficult even with experience.
- electroform metal over the surface and refinish.
- otherwise cover with metal (sprayed metal, vapour deposition etc) and refinish.
- use a rotary burnisher with the flexible shaft, emery and polish.
- burr a hemisphere into each pit individually, solder small sterling balls into the depressions.
- Identify the point in time when the problem occurred. e.g. pits are identified as gas bubble pits. Pitting must have occurred during the melting, casting and freezing of the metal.
- Identify cause of the problem at the moment it occurred. e.g. Excess oxygen or other gases dissolved in molten metal (silver) during the melting process. During freezing the oxygen comes out of solution, is trapped in the freezing metal and forms small holes – porosity and pits, often near where the sprue enters the model. If the pits are accompanied by pinkish-purple discoloration around them and “comet trails” (little pointed tracks that appear when polishing because there is hard inclusion in the metal which acts like a rock on a windy beach to protect the metal behind it from the buff-thus creating a “comet trail”) then overheating has occurred an copper oxide inclusions have been formed. If the pits are not all rounded and appear to have shiny interiors when encountered during sanding then they may be due to shrinkage problems and an insufficient or illogical supply of material to the cooling casting from the button.
- List ways of avoiding the problem at the moment when it occurred.
- Melt in an oxygen free atmosphere.
- reducing the flame and a chunk of charcoal in the crucible.
- use of an induction melting crucible, sealed from the air with a layer of charcoal on the molten metal, sand may also be used, neutral gas atmospheres may be added.
- Add a precipitant to the melt just prior to casting. In refineries a tiny piece of zinc is sometimes added before casting to remove excess oxygen. Other chemicals are also added in this way but this method releases toxic gasses or metal (zinc) fumes.
- Choose best solution and apply it next time.
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