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Rasps: Teeth Raised One at a Time with a Pointed Punch
A rasp is a coarse file whose teeth stand separately instead of in continuous rows. Each tooth is raised by driving a pointed punch into the face of the blank at uniform distances. Because the teeth stand apart, a rasp clogs less than a cut file on soft material such as wood or a horse's hoof. The blank is forged, annealed and ground like a file blank, and the finished rasp is hardened like a file: coated against scale, brought to a dull red heat and plunged into water, with the tang tempered so it will not snap. Machine-made rasps have uniformly stamped teeth, which line up row behind row and leave deeper marks; slightly uneven hand-cut teeth avoid this.
Advanced
2 days (annealing overnight)
Instructions
1
1
Forge the blank
Forge the blank
Forge the steel to a tapered bar, flat, round or half-round, with a narrow pointed tang at one end.
Materials for this step:
High-carbon Steel Billet0.5 kgTools needed:
Blacksmith Forge
Anvil
Forge Hammer
Forge Tongs2
2
Anneal and grind
Anneal and grind
Anneal the blank soft so the teeth can be raised, then grind the faces to a smooth, clear surface.
Tools needed:
Blacksmith Forge
Grindstone3
3
Punch the teeth
Punch the teeth
Drive the pointed punch into the face with the hammer at uniform distances, raising one separate tooth at each blow. Turn the rasp over on a soft metal plate to work the other face without crushing the finished teeth.
Tools needed:
Rasp Punch
Forge Hammer
Anvil
Pewter Plate4
4
Harden
Harden
Coat the toothed surface thickly with a salt composition against scaling, raise the rasp to a dull red heat in a clear coke fire and plunge it upright into water. If it bends, straighten it across a fulcrum before it is fully cold.
Materials for this step:
Salt1 kg
Metallurgical Coke1 as requiredTools needed:
Blacksmith Forge
Bucket
Forge Tongs5
5
Temper the tang and clean
Temper the tang and clean
Temper the tang by dipping it in molten lead so it will not snap. Scour and wash off every trace of salt, then brush the rasp with oil.
Tools needed:
Molten Lead Bath
Forge TongsMaterials
3- 0.5 kgPlaceholder
- 1 kgPlaceholder
- 1 as requiredPlaceholder
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