The iron needs to be checked for the shape and sharpness of its cutting edge and its flatness.
The usual shape of the cutting edge for a block plane iron is straight, as the plane is used mainly on edges that need to be exactly perpendicular, or square, in relation to adjoining edges.
If you need to take the camber off an iron’s cutting edge, you can do it by re-bevelling with a grinder (an electrically-powered machine for grinding metal edges) or on a sharpening stone or abrasive paper, but the latter two methods could take a long time.
If the iron’s cutting edge is already straight, take a look at How to flatten and sharpen bench plane ironsfor a step-by-step guide to ensuring your iron is perfectly flat and razor sharp.
Step 3 – Remove iron from plane
While it’s possible to check the iron’s sharpness and the shape of its cutting edge when it’s still in the plane, you will need to remove it for sharpening, flattening and to check the flatness of the bed beneath it.
To remove the iron, release the lever cap by turning the cam lever if fitted, or the thumbwheel release above or below the cap, or by lifting the top of the cap if it’s a knuckle-joint lever cap.
Lift the lever cap out then lift the blade off its bed, clear of any lateral adjustment plate and depth adjustment lug or “tooth”.
Step 4 – Check iron’s bed
With the iron removed, it’s now possible to check the bed (the sloping “ledges” that the iron sits on) for any debris.
Metal filings and other particles on the bed will prevent the iron lying flat, affecting the “trueness” of the plane. Clean out any particles with a rag or brush.
Step 5 – Refit and adjust iron
When refitting the iron, if the plane has iron depth and lateral adjustment, be sure to locate the lateral adjustment plate in the iron’s large slot.
Ensure also that the lug or tooth of the depth adjustment lever, if fitted, fits into the appropriate lateral slot of the iron. After “bedding” the iron, place the lever cap over the top, behind the lever cap screw or crossbar, and tighten with the cam, thumbwheel or knuckle-joint fastener.
Step 6 – Lateral adjustment
With a small projection of the iron’s cutting edge beyond the mouth, sight along the sole of the plane to check the iron’s lateral position.
If it’s not parallel with the sole across its width, adjust with whatever kind of lever is provided or, if there’s no adjustment mechanism, move the iron by hand to achieve the right position.
You may need to slacken the lever cap thumbwheel or screw to release the pressure on the iron before making the adjustment. Remember to tighten again afterwards. A lever cap should be just tight enough to hold the blade firmly in position, and not overtightened.
Step 7 – Depth adjustment
Sighting along the sole, adjust the depth of the blade via the adjustment wheel if the plane has one, or by hand if it hasn’t.
Again, you may need to slacken the lever cap thumbwheel or screw and re-tighten after making the adjustment.
With a block plane, you generally need minimal iron depth, particularly for end grain work. However, the first few passes when chamfering may call for greater depth until the chamfer widens out towards its required size, when you can retract the blade a little for the final strokes.
Step 8 – Mouth adjustment
If your block plane has mouth adjustment, it needs to be set in step with iron depth. A thick shaving requires a larger mouth, a wafer-thin shaving, a tight one.
Turn the front knob anti-clockwise. If fitted, turn the mouth adjustment lever below the knob left or right to increase or reduce mouth size. If there is no lever, pushing or pulling the loosened knob will move the plate. Turn the front knob clockwise to lock the mouth at the required opening.
Step 9 – Test
Now begin planing, checking that you get a shaving that is consistent across its width, that the iron cuts smoothly and there is no tear-out of the wood. Further adjust as necessary until you get perfect results.