Cabinet/Card Scrapers

Cabinet/Card Scrapers

One of the most useful, versatile and inexpensive items, which should be in every toolbox, is the ordinary cabinet scraper. Few are aware of how to use this workhorse correctly, and even more do not know how to sharpen it. I would like to share how to make this ancient tool perform magic in situations where much more expensive tools struggle.

Scrapers are a whole class of tools used by woodworkers and woodturners. While we strive to bring the edge of planes and chisels to a polished, acute edge, free of burr, we purposely bring the edge of a scraper to a tiny, well-defined burr and then proceed to use the tool by dragging the burr against the wood. It is the burr that does the cutting, and raising this burr along the edge of a steel scraper is a bit of an art.

Tools for sharpening a cabinet scraper
A file and a round burnishing rod are two tools essential to sharpening a cabinet scraper.

As you can see in the photo at the top of this page, cabinet scrapers come in a variety of shapes. They are often sold in a set of three to cover a variety of scraping tasks. This set, made by Crown Hand Tools in Sheffield England, a rectangular cabinet scraper (often called a card scraper), one with inside and outside radii at each end and a French curve. The card scraper is used on flat surfaces.

The edges of the middle scraper can also be used on flat surfaces while the ends will fair and smooth concave and convex surfaces. Some part of the French curve will generally shape and smooth complex shapes and often saves the day. The set from Rockler costs a mere $21.

Scraping wood with a sharp chisel
Traditional woodworking tools such as this chisel or a plane blade are ground and polished to an acute cutting angle — 25 degrees, in this case. They raise a chip and leave a smooth finish in their wake when cutting clear, straight-grained wood. They do not rely on a burr to provide the cutting action.

While chisels and plane blades are tempered to a hardness on the Rockwell C Scale (HRC) of 58 to 64, a cabinet scraper wants less temper, so they are generally delivered at HRC 50 to 55. The lower temper is necessary to allow burnishing that creates a sharp burr at the edge. Burnishing is both a tool and a process. A burnisher is a round rod with a handle that is a bit like a file without any teeth. In fact, it is delivered with a polished surface and is HRC 64 or higher.

Sharpening a Scraper

Rockler cabinet scraper sharpening system
Rockler’s unique 3-in-1 Cabinet Scraper Sharpening Tool, integrates a double-cut file, 2,500-grit diamond stone and a hardened-steel burnisher in the same tool to simplify the entire process of sharpening a flat-edged cabinet scraper.

The process of sharpening a scraper in my “More on the Web” video that supports this article. In a nutshell, the process involves filing and honing the scraper’s edge square and smooth, then using the burnisher to distort the steel into a tiny burr that curls over the face of the scraper. It’s not particularly difficult, but it does require practice.

Filing down damaged card scraper edge

To prepare a scraper for burnishing, the work-hardened area is first removed with a mill file. This will be followed by a whetstone to smooth away file marks.

Drawing of damaged card scraper edge from over burnishing

The result of over-burnishing by pushing down too hard or taking too many strokes is a ragged edge rather than a continuous sharp one.

Diagram of proper angle for burnishing card scraper

Once the edge is filed and stoned smooth and square, a burnisher is sloped 5 to 15 degrees downward from the edge and drawn across the corner of the scraper to form a sharp burr. Definite pressure is necessary. Do not make the burr too big or it will split into segments at the burr’s point. You may turn burrs on both corners of an edge.

Applying pressure to burnishing tool during sharpening

The process work-hardens the edge, so it cannot be repeated without using a file to remove the workhardened area. The edge is then refined with a fine stone to form perfect corners. Back to the burnisher to create a new burr again.

Using freshly burnished card scraper

Cabinet scrapers have a wide variety of uses — removing depressions or torn-out grain, flattening misaligned joints, cleaning off dried glue or removing old finishes. So much utility from a small piece of steel!

Antique scraping plane from Stanley

Until 1943, Stanley made the #112 Scraping Plane. It’s a scraper on steroids with a much heavier blade that does not cramp your hands.

Using a Cabinet Scraper

Smoothing lumber with a card scraper
While it only removes small amounts of material, it does not tear when going against the grain in figured woods. It will also smooth a low spot that may not be smoothed with a plane or sander without removing a lot of surrounding material.

Once sharp, the scraper is held in both hands with thumbs flexing it into a gentle arch and tilting the tool slightly forward. The burr is engaged against the surface of the wood and pushed to scrape tiny, fine curls. Holders for card scrapers, which put a slight side-to-side bend in them with a handle at each edge, can make using a cabinet scraper much less tiring on your hands.

Diagram of a cabinet scraper burr
Card scrapers are burnished to a pronounced burr. The scraper is leaned forward and a slight side-to-side bend is induced into it by the user. It can only cut to the depth of the very sharp burr.

A scraper used with skill can cut through tiny depressions or torn-out grain without leaving marks. It can cut with or against the grain with equal verve and is handy for flattening uneven joints or removing dried glue residue.

Rockler rubber cabinet scraper holder
Rockler offers an adjustable holder for card scrapers that features soft overmolds to help make using these tools even easier and more comfortable.

When you need to get into areas that planes or sanders will not reach, here’s the tool for the job. It is also the best tool for stripping off an old finish. I use a card scraper every winter to scrape wax from my cross-country skis. You can’t beat the price-to-utility ratio of this simple, handy tool!

Posted in: