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Forged Centre Punch, Hardened and Tempered
A centre punch marks the spot for a drill. It is forged from tool steel like a cold chisel: the point is tapered at a yellow heat and ground to an angle between 60° and 90°. Only the point is hardened: heat the end about 3 inches back, dip the point in water at about 70 °F (21 °C) while moving it, polish it, and let the heat left in the shank run down until the point turns brown or purple, about 500–525 °F (260–275 °C); then cool it completely. A good punch marks tool steel without its point going dull.
Intermediate
1–2 hours
Instructions
1
1
Forge the taper
Forge the taper
Heat the end of the tool steel bar to a yellow heat and forge a long taper to a blunt point; finish just above the hardening heat, never hammering it black.
Materials for this step:
Octagonal Tool Steel Bar1 pieceTools needed:
Blacksmith Forge
Anvil
Forge Hammer
Forge Tongs2
2
Cool and grind
Cool and grind
Let it cool slowly, then grind the point to an angle between 60° and 90°.
Tools needed:
Grindstone3
3
Harden the point
Harden the point
Reheat about 3 inches of the point end to the hardening heat, keeping the tip high in the fire. Dip the point into clean water at about 70 °F, moving it so no sharp line forms, then plunge briefly and lift out with heat left in the shank.
Tools needed:
Blacksmith Forge
BucketForge Tongs4
4
Temper
Temper
Polish the point quickly and watch the colours run down to it; when the point is brown or purple, cool the whole punch completely.
Tools needed:
Emery ClothBucket5
5
Test
Test
Strike a mark in a piece of tool steel; the point should not dull.
Tools needed:
Forge HammerMaterials
1- 1 piecePlaceholder
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