Complete Chisel and Punch Forging: From Bar to Edge
Chisels and punches are essential tools for woodworking, masonry, and metalworking. This campaign covers cold chisels, wood chisels, punches, and proper heat treatment for each.
Chapter 1: Chisel Types
Type
Material
Edge Angle
Use
Hardness
Cold chisel (flat)
Medium-high carbon steel
60-70°
Cutting cold metal
HRC 52-56
Hot chisel (hardy)
Medium carbon steel
30-40°
Cutting hot metal on anvil
HRC 48-52
Wood chisel (bench)
High carbon steel
25-30°
Paring and chopping wood
HRC 58-62
Wood chisel (mortise)
High carbon steel
30-35°
Chopping mortises
HRC 56-60
Masonry chisel (point)
Medium carbon steel
60-70°
Breaking stone
HRC 50-54
Cape chisel (narrow)
Medium-high carbon steel
60-70°
Cutting grooves in metal
HRC 52-56
Chapter 2: Cold Chisel Forging
Cold chisel forging: 1) Start with 3/4 inch octagonal or round tool steel (S7, H13, or 1060). 2) Cut to length: 6-8 inches. 3) Heat one end to bright orange. 4) Forge cutting end: draw out to flat, 1-1.5 inches wide. 5) Forge edge angle: 60-70 degrees (blunt for cold metal). 6) Shape head end: slight chamfer (prevents mushrooming). 7) Heat treat: harden cutting end (quench 1 inch of edge in oil). 8) Temper to purple/blue (500-560°F). 9) Head should be softer than edge (absorbs hammer blows without chipping). 10) Grind edge to final angle.
Dimension
Small Chisel
Medium Chisel
Large Chisel
Stock diameter
1/2 inch
3/4 inch
1 inch
Length
5-6 inches
6-8 inches
8-10 inches
Edge width
1/2-3/4 inch
3/4-1 inch
1-1.5 inches
Edge angle
60-70°
60-70°
60-70°
Temper color
Purple
Purple
Purple
Chapter 3: Wood Chisel Forging
Wood chisel forging: 1) Start with high carbon steel bar (1/4 x 1 inch for 1-inch chisel). 2) Forge blade: maintain flat, even thickness. 3) Forge tang: draw out to 3/8 inch round, 2-3 inches long. 4) Blade should be flat on back (critical for accuracy). 5) Grind bevel on front: 25 degrees for paring, 30 degrees for mortise. 6) Heat treat: harden blade (quench in oil). 7) Temper to straw/dark straw (400-430°F). 8) Flatten back on stone (must be perfectly flat). 9) Sharpen bevel on stones (coarse to fine). 10) Fit handle: hardwood with brass ferrule.
Chisel Width
Stock Size
Tang Length
Handle Length
Best Use
1/4 inch
1/4 x 1/4 inch
2 inches
4-5 inches
Detail work, small mortises
1/2 inch
1/4 x 1/2 inch
2 inches
5-6 inches
General purpose
3/4 inch
1/4 x 3/4 inch
2.5 inches
5-6 inches
General purpose
1 inch
1/4 x 1 inch
3 inches
5-6 inches
Mortises, heavy paring
1.5 inch
1/4 x 1.5 inch
3 inches
5-6 inches
Wide paring, cleaning
Chapter 4: Punch Forging
Punch Type
Tip Shape
Use
Stock
Temper
Center punch
Sharp point (60°)
Mark drill locations
3/8-1/2 inch round
Purple
Drift (round)
Tapered cylinder
Open and size holes
1/2-1 inch round
Blue (tough)
Drift (oval)
Tapered oval
Size hammer eyes
3/4-1 inch
Blue
Slot punch
Rectangular
Punch slots (hammer eyes)
3/4 inch square
Purple
Decorative punch
Various (star, circle, etc.)
Stamp patterns in hot metal
3/8-1/2 inch round
Purple
Nail header
Tapered hole in plate
Hold nail for heading
3/8 inch plate
N/A
Round punch forging: 1) Start with 1/2 inch round tool steel, 6-8 inches long. 2) Heat one end to bright orange. 3) Forge taper: round cross-section, tapering to point. 4) Point diameter: size of desired hole. 5) Chamfer head end (prevents mushrooming). 6) Heat treat: harden point (quench 1 inch in oil). 7) Temper to purple (tough, resists chipping). 8) Use: heat workpiece, place punch on mark, strike with hammer.
Chapter 5: Maintenance and Safety
Issue
Cause
Solution
Mushroomed head
Repeated hammer strikes
Grind head back to chamfered shape
Chipped edge
Too hard, wrong angle, or hitting too-hard material
Re-temper softer, check edge angle
Bent chisel
Striking off-center or too-thin stock
Straighten while hot, use thicker stock
Dull edge
Normal wear
Regrind to original angle
Flying chips
Mushroomed head or brittle edge
Grind head, check temper
Reference Card
Edge angle matches the material (60-70° for cutting cold metal, 30-40° for hot metal, 25-30° for wood; using the wrong angle causes chipping or poor cutting). 2. The back must be flat (a wood chisel with a flat back registers against the wood surface and produces accurate cuts; a convex back makes the chisel dig in unpredictably). 3. Temper harder for cutting, softer for impact (a wood chisel edge needs to be hard (straw temper) to hold an edge; a cold chisel needs to be tougher (purple temper) to absorb impact). 4. Grind the mushroomed head (repeated hammer strikes spread the head of a chisel into a mushroom shape; these thin edges break off and fly like shrapnel; grind the head back to shape regularly). 5. A cold chisel cuts cold metal (the name means it cuts metal that is cold, not that the chisel is cold; it is designed with a blunt angle to withstand the impact of cutting unheated steel). 6. The punch makes the hole (a punch driven through hot metal creates a clean hole without removing material; the metal displaces around the punch). 7. Oil quench for tool steel (most tool steels should be quenched in oil, not water; water quenching is too aggressive and causes cracking in high-carbon and alloy steels). 8. A matched set of chisels is a woodworker's foundation (a set of bench chisels in 1/4, 1/2, 3/4, and 1 inch widths handles most woodworking tasks; they are among the first tools to forge).
