Techniques/sharpening

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Knife Sharpening - An aide Memoire

Starting Point: Shape of knife already done and rough bevel created

General Notes=

  • Can sharpen anywhere from 7 degrees (razor blade) to 45 degrees (axe head)
  • Sharpness depends on what you're cutting, not much point going above 1000/1500 (and strop) with wood
  • All Stones used wet- to aid lubrication and cleaning off swarf
    • Water stones:
      • kept permanently submerged in water.
      • Only use water. Certain stones can be used with oil but then can never be used with water again.
      • Water stones may not be completely flat from previous use (dished). Can flatten with 400 Diamond Stone
    • English stone can be kept dry but needs to be soaked in water for half an hour before use.
  • Both Water and English stones need even more care on push stroke to prevent nicking stones.

General Process

  • Firm Pull stroke on stones, very light push stroke (to prevent nicking stones)
  • Should only have to do 400 Grit when first shaping edge, unless you've badly nicked the blade
  • Clean Knife between grits - otherwise previous swarf can scratch blade - water and wipe
  • Alternate both sides until there's a burr one side all along blade that can be pushed to the other side. Can feel burr with finger
  • Then do 10 strokes on one side, then the other. Then 9 strokes on each side... repeating down to 1 stroke.
  • Repeat for each grit

400 Grit Diamond Stone

  • Result under microscope: Dull with obvious scratches
  • Can feel burr with finger

1000 Grit Diamond Stone

  • Result under microscope: Silky matt consistent across bevel with less obvious scratches
  • Repeat above process, can still just feel burr with finger

1500 Water Stone

  • Result under microscope: Bright silky matt, little scratching
  • Repeat process - likely trouble to feel burn with finger

3000 English Stone

  • Result under microscope: Shiny, no scratches

4000 F3 (triple fine) Water Stone

  • Result under microscope: Shiny but reflective, matt mirror

Often stop here, apart from stropping

Could continue to repeat process with 8000 stone

  • Result under microscope: Visible shine to cutting edge across whole blade

Stropping 30000 grit

  • Done to polish edge to help, to help item being cut slide across blade.
  • Result under microscope: Definite shine, like mirror
  • Only pull strokes, 30/40 on each side with stropping compound

Time Taken=

  • 30 mins for 4000 grit, 10 mins for each after that
  • Highend tool steel - double numbers above
    • Very high grade (e.g. D2, CPM140) - 6 hours total

Resharpening Blade

Minor touch up- strop Otherwise start at 1500/ 3000