Plane Iron Sharpening

Take a gander at my latest plane sharpening video, and the process and tips I regularly use and recommend.

Take a look at my recommended Sharpening Supplies if you don't yet have, or are not satisfied with, your sharpening system.

Plane Iron Sharpening - process, tips, and related videos:

Definition of a sharp edge: A sharp edge is the point where two highly polished surfaces meet at an angle, rather than blending in a curve.
To achieve this easily for a plane iron in the workshop:

First prepare the back of the blade flat: (in reality it will be the last few mm's (1/8" or so) that are important, as this is, where the chipbreaker will contact it if present and, to which the bevel surface will meet) Therefore, work the back on a flat abrasive until the last few mm's are totally ground.

Next polish the back: Now work through finer abrasives until this small area is polished. To mirror polish the entire back really is a thankless task!

The bevels: It is quite acceptable to prepare a single bevel at the required cutting angle. However, by initially grinding a shallower angle, and then preparing a short secondary bevel, at just under the required cutting angle, subsequent resharpening will be quicker since less metal will need to be removed at the bench stone (of course the shallower (primary) angle will need to be reground from time to time). The very slim polished tip of the secondary bevel, is known as the tertiary bevel.

The process: Start at highest possible step, based on the appearance of the iron - e.g. small chips on the edge and plenty of primary bevel left,  start at 3. Don't worry if this sounds daunting - if you start too high you'll find you get nowhere, and you can take a step backwards. If you start too low, you'll just lose a little more steel than you need to. The more irons you sharpen, the more efficient you will become. (Step 1 can be omitted where no grinding wheel is available.)

1. Grind a shallow, hollow bevel of 20° to 25° on a coarse wheel, quenching frequently and avoiding reaching the back of the iron, in order to prevent annealing the steel.

2. Grind the primary bevel on a coarse bench stone, using a honing guide to establish the angle (20° to 25°) or by working the heel and toe of the hollow grind until a flat approaches the tip.

3. Grind the secondary bevel on a medium/fine bench stone, using a honing guide to establish the higher angle (30° to 32° is a fair choice for working soft to moderately hard woods) or by feeling the primary on the stone and then lifting the heel up appropriately to grind. The secondary bevel need not exceed a couple of mm's (1/16"), as this will impart sufficient additional support to the cutting edge, but it should produce a continuous wire edge to the blade.

4. Polish the tip of the bevel, on a fine/super fine bench stone, to produce a tertiary bevel of a mirror finish. Once again a honing guide can be used to raise the angle another couple of degrees, or this can be done purely by feel.

5. Remove the wire edge by laying the back of the blade on the last bench stone, and pulling backwards while applying downward pressure over the heel.

6. Finally strop the edge on a flat piece of leather charged with polishing compound, alternately on the iron's bevel and back, several times. The sharpened iron should easily shave the hairs off your arm!

Step 6 can often be repeated a dozen times to refresh the edge, so long as you do it as soon as the cutting performance initially deteriorates.

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