How to Fettle a Combination Plane

If you plan to recondition an old combination plane, you will likely have to fettle the base of the plane to make it usable again. To fettle a plane is to flatten the bottom of the base plate. The base plate runs against the wood and allows the cutter, which protrudes from the bottom of the base plate, to cut the wood. If the base plate is warped, it will not allow the plane to cut evenly. This renders the plane useless for any precision work.

Plate glass
120-grit sandpaper
Precision straight edge
Feeler gauge set

Instructions

- 1
  Tape a 24-inch long strip of 120-grit sandpaper to a flat surface. Plate glass works well as it will be very flat.
- 2
  Retract the blade so it rests inside the plane and does not protrude from the base plate.
- 3
  Position the base plate of the combination plane on top of the sandpaper. Rub the plane up and down the length of the sandpaper several times.
- 4
  Inspect the bottom of the plane. You will see shiny metal where the sandpaper removed metal from the base plate. You will see tarnished metal as well. The tarnished metal indicates depressed areas in the surface of the base plate. You must sand the surface of the base plate until the entire base plate consists of shiny metal.
- 5
  Place the base plate against the sandpaper and continually sand up and down the length of the sandpaper for three to five minutes. Inspect the bottom of the base plate and then repeat the process until the entire base plate is shiny metal.
- 6
  Check flatness with a precision straight edge. You should see very little light between the straight edge and the base plate. If you can fit a feeler gauge that measures thicker than 1 1/2- thousandths of an inch, you must continue to sand until you have the base plate completely flat.

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