If any of you have seen me demonstrating sharpening 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. This idea is attributed to David Charlesworth, a well known furniture maker from North Devon, and 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, and to get a nicely polished surface on the back of the 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 as the finish on the rest of the back will have no influence on the sharpness of the cutting edge. Concentrating our efforts 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 and the area immediately behind the cutting edge will be the only part in contact with the stone.
If we now work the iron back and forth on and off the stone and work along the length of the stone to distribute the wear evenly we 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 as it is best to avoid contaminating the fine stone with the coarser particles of the medium stone.
One final point worth noting is that to maintain flatness on our tool blades it is essential to keep our sharpening stones flat at all times. With water stones, this is best carried out by either working the stone back and forth on some abrasive paper on a known flat surface such as a granite surface plate or, if you have one, working a diamond stone across the surface instead.
Please note: the “Ruler Trick” is only suitable for use with plane irons and not chisels, as the back of a chisel needs to remain totally flat and used as a reference surface to guide the tool.