Hand lapping is a time honoured process for imparting extremely precise surfaces onto hard materials. In the modern woodworking shop it remains an accessible method that saves time and effort by bringing blades to a condition where they are very easy to hone.
The MJ Platt & Co. Kanaban lapping plate begins life as a billet of hot rolled, low carbon manganese steel. We choose this material because it was shaped above its recrystallisation temperature, giving it the twin virtues of being soft and completely free of any internal stresses, so it holds grit and flatness beautifully.
After carefully machining away the outer crust of the billet, the ends are milled square and the long sides of the plate are given a hand curled finish – a traditional technique that produces a durable finish for surfaces that will be handled. The working faces are then precision surface ground in multiple orientations to be flat to well within +/- 0.012mm or half of one thou inch.
For the abrasive, we recommend Chemico grinding paste, let down with a little WD40 as necessary. Chemico contains silicon carbide grit in a tenacious lithium grease base, the abrasive particles are very hard, sharp and brittle, so they break down in size but continue to cut – effectively taking themselves through the grits. You can go back to 80 or 220 at any point by adding more, but you don’t need to worry about cross contamination or having separate plates for different grits.
Your MJ Platt & Co. Kanaban lapping plate is not corrosion resistant, we recommend storing it lightly oiled, protected with fresh VCI paper, and kept in a warm dry place.
If you are not familiar with lapping, please review the frequently asked questions here.
Dimensions: 14mm x 70mm x 200mm or a strong ½” x 2-3/4” x 8” (+/- 2mm)
Hardness: 140HV (just below the beginning of the Rockwell C scale)