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44 INSTRUMENTS AND APPLIANCES
Temperature Color Use
2i7° to 232''C light yellow enamel chisels, burnishers.
243°C medium yellow excavators, scalers.
258°C brown-yellow pluggers.
266°C brown-purple saws, shanks of instruments.
279° to 299°C blue spring temper.
Technical Exercises in the Working of Steel
1. Making Smooth Broaches and Canal Explorers.—Cut
piano wire of the desired gauge to the required length and
file to a point with a long taper; or utilize old, worn pulp
canal cleansers for the same purpose by filing off the barbs
and reducing to the desired size and taper. Remove file
marks and polish with emery paper. These may be later
used in the technic course as canal explorers and dressers.
The points of those intended to be used for explorers and for
placing cotton dressings in canals, where they are to be left
temporarily, should be filed to a sharp point. Cotton,
wrapped around a broach of this kind, has a natural tendency
to come off. Those intended for swabbing and drying the
canals, where it is desired to withdraw the cotton with the
broach, should have their ends cut off square^ with a pair
of scissors, when it will be found that, when wrapped with
cotton, they will retain it very readily.
2. Making Hooked Extractors.—Place the point of a
piano wire broach (as made in No. i) on an anvil. Lay the
sharp blade of a knife J^ inch from the end, with the edge
of the blade pointing toward the shaft of the broach. Elevate
the shaft of the broach, when the hook may be made at either
a right, acute, or any desired angle, depending on the degree
of elevation of the shaft. File the point to the desired length
and sharpness. Polish as before.
3. Exercises to Illustrate Annealing, Hardening and
Tempering
44 INSTRUMENTS AND APPLIANCES
Temperature Color Use
2i7° to 232''C light yellow enamel chisels, burnishers.
243°C medium yellow excavators, scalers.
258°C brown-yellow pluggers.
266°C brown-purple saws, shanks of instruments.
279° to 299°C blue spring temper.
Technical Exercises in the Working of Steel
1. Making Smooth Broaches and Canal Explorers.—Cut
piano wire of the desired gauge to the required length and
file to a point with a long taper; or utilize old, worn pulp
canal cleansers for the same purpose by filing off the barbs
and reducing to the desired size and taper. Remove file
marks and polish with emery paper. These may be later
used in the technic course as canal explorers and dressers.
The points of those intended to be used for explorers and for
placing cotton dressings in canals, where they are to be left
temporarily, should be filed to a sharp point. Cotton,
wrapped around a broach of this kind, has a natural tendency
to come off. Those intended for swabbing and drying the
canals, where it is desired to withdraw the cotton with the
broach, should have their ends cut off square^ with a pair
of scissors, when it will be found that, when wrapped with
cotton, they will retain it very readily.
2. Making Hooked Extractors.—Place the point of a
piano wire broach (as made in No. i) on an anvil. Lay the
sharp blade of a knife J^ inch from the end, with the edge
of the blade pointing toward the shaft of the broach. Elevate
the shaft of the broach, when the hook may be made at either
a right, acute, or any desired angle, depending on the degree
of elevation of the shaft. File the point to the desired length
and sharpness. Polish as before.
3. Exercises to Illustrate Annealing, Hardening and
Tempering
