We compared 14 methods to find the fastest way to prepare this useful tool.
Editor’s note: this article originally appeared in the February 2007 issue of Popular Woodworking
Scrapers are one of the most misunderstood but useful tools in a woodshop. A scraper in its basic form is simply a piece of hardened steel with a small hook that is created by pressing on the tool’s edge with an even harder rod of steel. This tool is capable of making tear-out free cuts in hardwoods that no plane can manage.
But how to sharpen a scraper is a mysterious or confusing process for many woodworkers. One reason for the confusion is that there are many different published techniques out there, many of them offering conflicting advice.
So I compiled a list of 14 different techniques for sharpening this rectangle of steel that have been published since 1875. All of the 14 techniques basically agree that there are three steps to sharpening a scraper: Filing the edge of the tool, removing the file marks with a sharpening stone and then creating the hook (sometimes called the burr) with a hardened rod of steel, usually called a burnisher.
But none of the accounts agree on the details. Should you file the edge of the scraper with the file parallel to the edge or at an angle (and if so, what angle)? What kind of file should you use? Should you stone both the edge and faces of the tool? To what grit? And how should this be done?
Do you have to burnish the faces of the tool before turning the burr of the scraper? If you do, what angle do you use? And how should you burnish the edge to create the hook? At what angle? Do you slide the burnisher along the edge as you turn the burr?
So one weekend I tried all these techniques then compared the results. I used high-quality scrapers from Lee Valley, Bahco (formerly Sandvik) and Lie-Nielsen. All of the published techniques basically worked and created a tool that made shavings. Yet some techniques were faster, some required fewer hand skills to master and some made a hook that really grabbed the work.
After trying these techniques, applying my own training and talking to an expert on steel tooling, I think I’ve found a 15th way to sharpen the tool that doesn’t require a lot of equipment, and is fast and is easy for beginners.
Like Any Tool’s Edge
What’s important to understand is that a scraper is like any cutting tool and it responds to your sharpening efforts in the same, predictable way.
A sharp edge is the intersection of two steel surfaces (in a chisel, it’s the bevel and the face, which is sometimes called the back of the tool). Any cutting edge is at its sharpest when these two surfaces meet at the smallest point possible.
The edge becomes more durable as it gets more polished by higher grits. Polishing removes tiny scratches in the steel, and scratches are the places where the edge begins to break down and become dull.
A harder steel can also contribute to a more long-lasting edge. However, if it is too hard it can be fragile and susceptible to shock.
All these rules apply to scrapers. The cutting edge of a scraper is two surfaces: the edge and the face. The more polished those two surfaces are, the more durable and sharp the edge is. So with that principle in mind, here’s the thinking behind my scraper-sharpening technique.
Step 1: File the Edge
A permanent marker will help you determine if you have filed the edge sufficiently. Once the color has been removed, you are ready to stone the edge of the scraper.
The edge of the card scraper should be filed square to the tool’s faces (all the sources agree on this). You should use a fine file. Look for one with single rows of parallel teeth (this is called a single-cut file) and teeth that are fine, usually labeled “second cut” or “smooth.” Scrapers are soft and easy to file, so a coarse file will create deep scratches that are difficult to remove.