Smithery: How to Make a Bolo or Knife

Smithery is a process of hot working the metal to a desired shape by applying high impact pressure using machine tools or hand tools. Typical products are scissors, knives, bolos and others.

Equipment Needed:

  • Smith Hearth Furnace
  • Charcoal
  • Anvil
  • Quenching tank half filled with
  • Drill Press water or quenching oil
  • Blacksmith’s Hammer
  • Tong
  • Pedestal Grinder with 0 & 120 grits grinding wheel

Materials:

  • Medium Carbon Steel (C1043)
  • Emery Cloth
  • Polishing bar/compound/
  • Buffing Cloth crap steel like leafspring, etc.
  • Drill bits (1) set
  • Piece of wood-to be used
  • Sand paper s handle of the bolo (300-600 grits)

Procedure

  1. Select scrap material of right size and thickness. Place it into the furnace until its color begins to turn yellowish. By this time, the material has reached its plastic stage and is ready to be processed.
  2. Using the tong, remove the piece from the furnace and place it on the anvil. With the forging hammer, hit the material heavily and repeatedly until the right shape is obtained. To prevent from cracking, the material should be returned to the fire if it begins to cool before the right shape is obtained.
  3. Form the handle of the bolo/knife according to the desired design by placing the part into the fire again. Hammer it until the shape is achieved.
  4. For the desired dimensions and shape of the material, process the material by grinding manually or using the grinding machine. Use the 80 grits grinding wheel.
  5. Shape and sharpen the bladed edge by using a 120 grits grinding wheel.
  6. Hardened the blade edge of the semi-finished knife or bolo by heat treatment or tempering:
    • Place the material being shaped into the furnace, position the bladed edge nearest to the fire. Heat it until the piece turns red hot in color.
    • Immerse the piece into the quenching tank filled with water or oil. If the piece turns into chocolate brown color, the piece is hard and tough—the desirable mechanical properties of metal. Repeat the heat treatment procedure if it turns white (it is hard but brittle) until the chocolate brown color is achieved.
  7. Polish the entire piece into a mirror-like finish by using different and appropriate emery cloth sanding grits (300-600).
  8. To increase/enhance its shine, use a buffing cloth with polishing compound:
    • Attach the sandpaper to a round piece of wood then attach it to the grinder. Proceed to polish the bolo. Attach a buffing cloth with polishing bar/compound to the grinder and polish the entire bolo to the desired shine.
  9. Attach the wooden handle.
  10. Lubricate the entire piece with oil to prevent rust and to preserve the beauty of the entire piece before wrapping and storing.

For more information, contact:

Metals Industry Research and Development Center (MIRDC)
MIRDC Compound Gen. Santos Ave.
Bicutan, Taguig, Metro Manila
Tel. No. 837-04-31 to 38
Fax No. 837-04-30
www.mirdc.dost.gov.ph

 

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