Sharpening Plane Irons with The Ruler Trick

Sharpening Plane Irons- a brief overview

If any of you have seen me demonstrating sharpening plane irons at any of our events recently, you may have noticed I used a method of preparing the back of a plane iron using a thin six inch rule placed flat on one side of my sharpening stone. Attributed to David Charlesworth, a well known North Devon furniture maker, the method is commonly known as the "Ruler Trick".

To prepare the back of a plane iron prior to use can be a tedious process, especially if it isn't flat. To get a nicely polished surface on the back of the plane iron may take a considerable amount of time and effort.

The only part of the blade that really needs to be polished is the area immediately behind the edge. The finish on the rest of the back will have no influence on the sharpness of the cutting edge. Concentrating on this area of the blade only will minimise the time needed to prepare the back of the plane iron.

If we place a thin six inch rule flat on one side of our stone and lay our plane iron across it, this raises part of the plane iron. The area immediately behind the cutting edge will be the only part in contact with the stone.

Iron plane sharpening- the process

To distribute the wear evenly, work the iron back and forth on and off the stone and along the length. This will quickly achieve the desired result. If using water stones, then use the medium stone initially followed by the fine stone to polish the surface. When changing from the medium stone to the fine, be sure to wipe any residue from the blade. This is because it's best to avoid contaminating the fine stone with the coarser particles of the medium stone.

Finally, to maintain flatness on our tool blades it's essential to keep our sharpening stones flat at all times. With water stones work the stone back and forth on some abrasive paper on a known flat surface. A good example would be a granite surface plate. However, if you have one, working a diamond stone across the surface instead is a great alternative.

Please note: the "Ruler Trick" is only suitable for sharpening plane irons and not chisels. This is because the back of a chisel needs to remain totally flat. It also needs to be used as a reference surface to guide the tool.

Discover more…

Found my piece on sharpening plane irons useful? Why not take a look at our ‘Insights’ piece on Axminster Rider Bench Planes is definitely worth a read as we look at the products from concept to completion. Furthermore, The Resourceful Woodworker investigates 'Tippage' is a great insight into how to overcome issues when your plane refuses, despite your best efforts, to stay flat on the runway and tips to the side.