|Basic techniques of blacksmithing: A Manual for Trainers |
source ref: t0021e.htm
Total Time: 3 hours
* To identify and discuss different types of chisels and steels suitable for making chisels
* To practice uncoiling an automobile spring
* To hot-cut steel
* To make a cold chisel blank
* To use a grinding wheel and practice grinding techniques
MacPherson, "The Cold Chisel"
Weygers, pages 45 and 59
Materials: Automobile coil spring, 112" to 5/8" diameter (1¼ cm) (each team should have one coil spring available at their station), several types of chisels, woodworking, metalworking, stoneworking, etc.
* The chisels distributed in Step 2 should be assembled in advance.
* The procedure for making the cold chisel should be prepared on newsprint and ready to post in Step 9.
Step 1. (5 minutes)
Explain the objectives and outline the procedures.
Step 2. (10 minutes)
Identify and pass out several different types of chisels. Ask participants to try to determine the uses, properties, and forging methods of each one.
* Have the group compare the shape and design of the chisels.
* If possible, invite the group to experiment cutting with the chisels.
* Discuss the significance of the angle of bevel in cutting edges.
* Ask participants to speculate on the type of steel and temper of the various chisels.
* Also ask participants to give examples of how they have used one or more of the chisels in their work.
* Describe some potential dangers in chisel use, e.g., chipping the blade, striking hand with hammer.
Step 3. (5 minutes)
Ask the group to refer to the list of scrap metals from the last session and identify which ones would be most suitable for chisel-making.
Step 4. (5 minutes)
Display a cold chisel and ask the participants to explain its properties and uses.
* Refer the group to Session 4 when they used a cold chisel to cut round bar.
* Have them discuss other potential uses.
* Based on the chisel's function, ask the group to determine its carbon content and temper.
Step 5. (5 minutes)
Light your forge.
* If coal is used as a fuel, demonstrate how to build a fire using coke remaining from the first fire.
* If possible, ask one member of the group to review the steps involved in lighting the forge and have another assist you.
Step 6. (10 minutes)
Heat and uncoil two linear feet of bar from an automobile spring.
Emphasize to the group:
* the correct positioning of the coil spring in the fire
* the periodic turning of the spring to prevent burning
* the banking of the fire around the spring
* the importance of even heating
* the proper use and type of tongs for holding the spring
Step 7. (5 minutes)
Explain to participants how to determine the length of bar necessary to forge a chisel, to determine the point, and to hot-cut the bar accordingly.
Be sure to point out:
* that the spring should be cut most of the way through, then broken, to avoid damaging the hammer on the hardy
* that the hardy should be removed from the anvil when finished
* safety hazards involved in the process (i.e., hot foot)
Step 8. (25 minutes)
Have participants go to their assigned stations and ask each team to light the forge, heat and uncoil the available spring, and hot-cut the straightened bar to be used for the chisel.
* To make sure all participants understand the task, ask for a volunteer to repeat the steps. Also, ask if there are any questions before beginning.
* During the work, circulate among the stations providing input when necessary and encouraging appropriate hammering and accurate blows.
* Be sure to point out any hazardous practices.
Step 9. (5 minutes)
Reassemble the participants around your station, and explain the steps involved in making a chisel.
* Point out what you expect to accomplish during each heat and mention that they can expect to accomplish less for each heat.
* Have the steps outlined and posted on newsprint.
* The following steps may be included on the list:
- forge stock into eight-sided octagonal bar
- forge main bevel
- grind cutting edge
- chamfer striking end
Step 10. (10 minutes)
Demonstrate the forging of the cold chisel.
* Refer to each step as you work.
* Before you grind the demonstration chisel, point out injuries which can occur from improper grinding practices (i.e., the importance of wearing safety glasses).
Step 11. (5 minutes)
After the demonstration, review the steps with the group.
* Ask if there are any more questions before the group makes their chisels.
Step 12. (1 hour, 15 minutes)
Have participants return to their stations and forge, grind and chamfer the cold chisels.
* Again, circulate among the stations, giving input regarding hammering techniques, safety, etc.
* Have teams who finish early assist others in the final steps of grinding and chamfering.
Step 13. (10 minutes)
Reconvene the large group and ask the participants to identify and discuss problems encountered while making their chisels.
Step 14. (5 minutes)
Conclude the session by explaining to the group that they will temper their chisels during Session 8, "Heat Treating."
Briefly mention that the chisels are incomplete until annealed and tempered; two processes which will be discussed in depth during Session 8.