The cabinet (or card) scraper is one of the most basic and versatile of tools. It is capable of removing paint or glue, shaping fine detail, and finishing a surface where the best planes fail.
I consider the use of the term “scraper” to be a little misleading. The burr on the edge of the steel acts like a plane blade in creating shavings. Its cutting angle, however, is higher than any plane.
Cabinet scrapers are typically about 6” x 2” rectangles of steel. The steel is also typically about the same thickness and hardness as a saw blade, which is one of the reasons why old saws are often cut up to become cabinet scrapers.
New cabinet scrapers may be purchased from Sandvic, Lie Nielson, Lee Valley, and Crown, amongst others.
This article provides a pictorial in preparing the cabinet scraper for use as a finishing tool. Note that it is based on the images from an earlier essay on this subject. I have updated this with additional data and references. The images depict one edge being prepared. Generally I prepare all four sides at the same time. And I also prepare both sides of the edge, thus giving 8 sides ready for use.
From beginning to end, an edge should take about 3-5 minutes. This is reduced to about 30 seconds if all one is doing is renewing a recent burr. The full treatment (which is depicted here) is only necessary when you no longer obtain shavings but, instead, are creating dust. Dust is the sign that the burr is no longer cutting. Generally after I can re-burr an edge about 3 times before jointing it afresh. I work a lot with woods like Jarrah, which is hard and abrasive, and quickly dulls an edge.
The burnisher. This is a flat and smooth length of hard steel that is used to create the burr. Please do not be tempted to use the back of a chisel or a screwdriver, or the tyre iron … they are simply not smooth or hard enough to create the type of burr that will produce shavings that rival those of a plane. Remember, the surface of the burnisher you use will transfer to the edge of the scraper steel. Buy a dedicated burnisher. They are cheap enough.
An excellent one is made by Veritas
I purchased one made by Crown – not as good but it does a fine job (the LV has three diameters for different edges, while the Crown has just one size).
Later I made one of my own from a length of carbide rod given to me by a fellow Galoot. This has a delicate and light feel – which demonstrates that the pressure with which one uses a burnisher to extract an edge does not have to be heavy. Light is good.
Here it is below the Crown burnisher..
The Scraper Holder
The holder in the presentation below is one I made from a section of angle iron (this is actually a blade holder used on the Belt Sander Grinder). What one wants is a guide that will hold the file square to the blade when it is used to joint the steel’s edge. This is done to flatten and straighten the card scraper’s edge in preparation for smoothing, which occurs before turning the burr.
Since these pictures were taken, I have purchased the Lee Valley jointer holder as it has other uses (it may be used to joint at 45° as well as 90°, and it may also be use to joint a handsaw).
The Veritas jointer:
I use a bastard file to joint the edge, and a 1200 grit diamond stone to smooth the now flat but rough edge. The edges and sides of the scraper are smoothed on 1000/5000/8000 Shaptons.
IPreparing the Cabinet Scraper
Step 1 - Joint edge of the scraper.
With the file clamped in the guide, flatten and square the edge.
It is always a good idea to use a blue permanent marker to determine where the steel has been filed.
Step 2 – Smooth the edge using the diamond stone
Repeat the previous step, this time using the diamond stone to remove the file marks.
Step 3 – Smooth the faces
the edge has been flattened and smoothed, the faces must be flattened
and smoothed. I will use W&D sandpaper on glass to flatten ½”
around the border of the scraper.
The card is now taken to the waterstones. The edges and sides of the scraper are smoothed on 1000/5000/8000 Shaptons. It is just as viable in these final stages to use sandpaper (up to 2500 grit) or diamond paste (I would go 40, 10, 1 microns). What you use to build up a smooth surface is not important. What is important is that these are square and smooth.
a recent article in Popular
Christopher Schwarz suggested using the Ruler
(of David Charlesworth) when the steel is not flat enough to smooth
easily. This makes sense to me, but my first preference would be to
flatten the steel, per se. Do it properly once, and then you do not
need to do it again.
Step 4 - Draw the edge
Drawing the edge facilitates the burr.
The burnisher is held about 5 degrees to the face and 3-5 light strokes are made. Lubricate the metal surface with a drop of oil. The metal moves more than one imagines it will from the light pressure. Experiment with less first rather than more.
that the larger the edge drawn, the larger will be the burr (which
will create a thicker, coarser shaving), but also that the resulting
burr will be more fragile and easier to fracture.
Step 5 - Turn the burr
The burnisher is held at about 10 degrees to the edge and again 3-5 light strokes are made. Feel the resulting burr with a fingertip. It should be sharp.
Finally - The proof of the pudding and all that …
Shavings in hard, interlinked and short-grained Jarrah.
The cabinet scraper may be both pushed or pulled.
When it is pushed, the double-handed grip places the thumbs at the center of the blade, which causes it to be bowed. The advantage of this is that the blade forms a camber and prevents the ends digging in (in the same way as a cambered plane blade works). The greater the thumb pressure, the greater the bow. This is transferred to the wood surface. While this may be helpful for removing isolated sections of tearout, it will leave a scalloped surface if overdone.
For this reason, when smoothing a flat surface, my preference is to pull the scraper towards myself. This action tends to keep the blade fairly straight. It is also the reason why I like to prepare the short sides of the blade. These are stiffer and, consequently, resist bowing. I find these sides ideal when scraping narrow edges.