Metal and wooden scrub planes are similar in use, although the wooden plane may be a little lighter.
The blade of the scrub plane is usually set a little more “aggressively” than that of other planes – that is, it projects further through the mouth.
Deep and narrow is the rule for the scrub plane. The blade is narrow and it cuts deeply into the wood for quickly reducing the width or thickness of the workpiece.
Planing the face of a piece of wood (reducing its thickness)
Step 1 – Mark workpiece
With a pencil and straight edge, mark the depth you wish to plane down to on the edge of the workpiece and ensure it is properly held on the workbench between stops, or with some other securing device.
Place the toe of the plane flat on one of the corners of the workpiece and exert some downwards pressure on the front of the plane by pressing down on the front handle or knob.
If it’s a wooden plane and there isn’t a front handle, press down on the front of the stock.
Step 4 – Angle of planing
Push the plane across the face of the workpiece at an angle of between 30 degrees and 45 degrees to the grain of the wood.
Transfer the downwards pressure to the rear handle, or rear of the stock, as you approach the end of the stroke. This avoids the iron cutting too deeply at the end.
Step 5 – Lift and return
Lift the plane slightly after the cutting edge passes over the far edge of the workpiece and return it to a point slightly less than the plane’s width to the left or right of the first stroke. You should see that the first stroke has made a slightly hollowed out gouge diagonally across the workpiece.
Step 6 – Second stroke
Make your next cutting stroke alongside the first one, slightly overlapping it, and continue right across the workpiece.
Step 7 – Work from opposite end
When all of the side being planed has been covered with gouges in one direction, repeat steps 3 to 6, but this time starting from the opposite end of the workpiece.
Step 8 – Check pencil mark
Keep checking how close you are getting to your pencil mark, and stop just before you reach it.
When the workpiece has been reduced close to the required thickness, a jack plane can be used along the grain to make the final reduction and smooth out the gouges to a flat finish
Alternatively, if the criss-crossing, latticework effect left by the scrub plane is a desirable feature of the end product, then the scrub plane can be used to complete the reduction, with the effect left unrefined.
Dealing with tear-out
Tear-out of the far edge of the workpiece is often a problem when scrub-planing at 30 to 45 degrees across the face.
You can avoid tear-out by first planing a bevel on the top edge of the far side of the workpiece. The bevel needs to go down to the pencil line. Now when you plane across the face, the bevelled edge will prevent the wood from breaking out.
Planing the edge of a workpiece (reducing its width)
Step 1 – Mark with pencil line
Make a pencil line on the side of the workpiece indicating the depth to which the piece is to be planed.
If the grain slopes upwards at all towards the edge to be planed, ensure it is sloping away from the direction of planing, not towards it, to avoid tear-out. Turn the workpiece around if necessary. Any split will then move upwards into the chip being planed off, with no damage to the workpiece.
Step 5 – Position plane
Position the toe of the plane at the end of the edge to be planed.
Step 6 – Plane along grain
With downward pressure on the front of the plane, move the plane forwards with the grain, along the full length of the edge.
Step 7 – Lift and return
Transfer the downward pressure to the rear of the plane as you near the far edge.
With the blade having gone beyond the far edge, lift the plane slightly and return it to the starting point.
Step 8 – Repeat
Repeat steps 5 to 7 until you reach a point very slightly above the pencil line, with the edge being planed as level as possible along its length.
Other planes – jack, fore, jointer and smoothing – may now be used to further level and smooth the wood.