Hand and Cabinet Scrapers

Scrapers are among the earliest tools used by man.  Broken flint, chert, jasper or obsidian produces a razor sharp edge.  Rocks from stream banks or river bottoms that have conchoidal fractures, have smoothed spear shanks and arrow shafts for thousands of years.  It is impossible to make anything sharper than fractured obsidian volcanic glass.  Broken glass is still used as a fine scraper for crafting gunstocks and other fine woodwork.  Scraping is a method of removing fine shavings from wood that are scraped rather than cut as with a hand plane.  Metal scrapers differ from glass scrapers, as the angle of attack of the blade is shallower than with a glass scraper, which relies on its extremely sharp edge.  The metal scraper made of thin flexible steel and usually has a burr turned on its working edge.  This burr is small yet very sharp.  

Dressing the blade:  The scraper blade is made of quality high carbon steel of a uniform thickness of about .032 inches, and is formed into a variety of shapes, rectangle, swans neck, convex, concave, etc.  The edges of the scraper must be square to the flat sides no matter the outside shape of the scraper.  The first thing to do with a new or dull scraper is to flatten off the old burr if any, and to dress the sides flat.  This is easiest done with a file.  The outside edge of the flat side of the scraper must be shiny everywhere there will be a cutting edge.  This is done on both sides of the scraper, which gives you twice as much sharpened edge for cutting.  Some woods will dull a scraper quickly, the more edge you have sharpened, the more time between re-sharpening.  Once the sides are properly dressed the first time, you will spend less time in the re-sharpening process.  You can produce a smooth cut by draw filing the sides and the edges.  While it is usual to use a file along its length, and that is how you join the edge square, to get a smoother finish with a file you ‘draw’ the file perpendicular to the work rather than parallel to the work.  It is easier to draw file the flat sides to get the shine all the way around the cutting surfaces. The next step is to join the thin edge and this must be perfectly square.  There are special tools that hold a file or piece of file perfectly square to the surface being worked, these made for joining saws during sharpening, to join scrapers and to sharpen ice skates.  A wooden block can be modified to hold a file at 90 degrees.  I have used such tools, but after sharpening scrapers for nearly 30 years, I can get it square with a flat file.  Once the edge is joined, I draw file the entire edge to get it just right.  I put a slight belly in my flat hand scrapers and slightly round the square corners; this prevents the sharp corners from digging in and spoiling the work.   A small triangular file is best to join the inside edges of the inside curves on a swans neck or gooseneck scraper, a round file is not aggressive enough, it doesn’t have enough contact of its cutting teeth.  Now we have a metal hand scraper with perfectly square and smooth edge that already has a sharp 90-degree angle, and this is where the burr is to be formed by burnishing.  A burnisher is any piece of hard smooth steel, such as a screwdriver shank, drill bit shank, any piece of metal that will turn the burr on the steel scraper.   If your burnisher has a defect, a dent, gouge or burr it will damage the edge, the burnisher needs to have a smooth even surface.  Again, any oval, round, triangular or other shaped piece of steel will work, use what ever is handy and large enough to keep your fingers well clear of the edge you are working.  Place the scraper flat on your workbench with the edge at the edge of your workbench.  Hold down the scraper securely to the bench with one hand and with the other run the burnisher along the edge to be sharpened, on the flat of the blade, polishing and forming what will be the inside of the burr once its been turned down.  You first form a small burr on the top edge of the scraper and then turn that edge back down to form the burr.  Hold the burnisher almost parallel with the scraper on the bench; tip it a degree or two to form this first small burr.  One smooth continuous stroke is best, but you can go back over the edge, just make sure to maintain the same angle and that the burr is uniform.  This initial burr is so small it is more easily felt than seen, so brush across it lightly with your finger and feel for the drag.  Do not slide your finger along the burr, it will cut.  Use caution from this point forward, you are dealing with very small, extremely sharp cutting edges. Now it is time to put on the money edge.  This is a little tricky, some people prefer to clamp the scraper in a vice and finish the burnishing process bearing straight down.  Most continue to use the workbench and hold the scraper with the edge just over the edge of the workbench.  In either case, the burnisher is then used to turn the small burr back.  Working on the outer edge, the burnisher is placed at a 90-degree angle to the flat side of the scraper then pushed or drawn upon what would be the cutting edge if it were a plane iron or chisel.  If you were converting a freshly sharpened plane blade into a scraper this is exactly how it would be done.   Again, a smooth firm stroke is best.  You are now burnishing the burr back around to form a small hook.  This is usually done in a two-step process.  First turn the burr at about 85°and then turn it again another 5° or so to increase the curve and make the small hook that is the cutting burr.  As you use the scraper you will be able to monitor its sharpness by feeling the edge for the burr.  When the scraper is sharp it will remove fine shavings, as it dulls, it still scrapes but the shavings will be powdery.  The burr can be turned again to re-sharpen a couple of times, then the process needs to be repeated to produce a fresh cutting burr.

You can also use the scraper without the burr after the edges have been squared up.  This can be used where only a very fine scraping is required, where the burr cuts too much.  This is useful for scraping finishes flat.  The blade is held at about 60°angle and the blade is not flexed.

I will first discuss the hand scraper and finish with the cabinet scraper. There is nothing quite like a freshly sharpened hand scraper.  Used properly it produces a finish on wood that cannot be duplicated, doing in seconds what takes hours with sandpaper, and done well requires no further work prior to finishing.  Stain is better accepted in scraped wood, the pores of the wood are open and not sealed as sanding does.  The finish will penetrate and protect scraped wood better than a sanded surface.  With practice you can remove irregularities and produce a flat smooth finish on your work.  Scraping also deals with problems encountered in working wood with hand planes.  Difficult wood grain like birds-eye, curly, quilted, interlocking, crotch or burl grain can be more easily smoothed with a scraper than with any other tool.  The scraper is held with one or both hands, flat scrapers are held with both hands and the thumbs flex the scraper so the leading edge is convex and the angle of the scraper is tipped forward at about an 80° angle or less.  The burr is turned so in order to engage the cutting edge the scraper must be tipped forward.  Holding the scraper in two hands and flexing it concave gives the cutting edge a skew angle that as with every other cutting application produces the best results.

The cabinet scraper is in effect a hand scraper placed in a handled device.  Made of metal or wood these tools are excellent for fine finish work as the tool body holds the scraper at a uniform angle for flat results.  When hand scraping, the tool gets hot and your thumbs get tired.  The cabinet scraper isolates the heat and does not require the thumbs to maintain the convex flex of the scraper blade.  The tool itself holds the blade at 85° or less and provides the flex and secures the scraper blade in place.  Some cabinet scrapers do not have an adjustment screw to vary the flex of the blade.  A small piece of veneer or thin leather can be placed behind the blade in the cabinet scraper body so when the blade holder is secured the blade will flex.  The blade is placed so that just the center edge protrudes.  If the Scraper is adjustable, the blade is placed in the tool and secured with each side of the blade just at the sole of the scraper and the blade holder tightened.  When the adjustment screw is operated the blade flexes out and the scraper blade will begin to cut.  The further the screw is advanced the greater the cut of the scraper.

  The blade of the cabinet scraper is sharpened differently from a regular hand scraper, although a burr is still turned and does the cutting.  The cabinet scraper blade is sharpened like a plane iron with a 60 to 70° angle.  A slight belly is filed into the scraper as the angle is filed and the sharp corners slightly rounded to prevent digging in and ruining the work.  Burnish the flat (non-bevel) side as you would a hand scraper producing a shiny edge.  Place the blade with the bevel up in a vice and secure it firmly.  Burnish the sharp edge over 15° and produce a uniform burr.  Because of the bevel, the burr is much larger than on a hand scraper.  A cabinet scraper can do more work and is less tiring than a hand scraper, but used together produce results unobtainable by any other means.  Cabinet scrapers can also hold a tooth or key blade that produces toothing or keying for gluing.  I made a toothing blade by engraving small parallel grooves close to each other on the flat side of the cabinet scraper blade.  I used an engravers burin to form fine teeth on the edge of the blade.  Using the toothing scraper in a cabinet scraper body will smooth irregularities from surfaces prior to gluing.

Summing up, yes, you have to buy or make these scrapers, dress the blades, etc., but the results are worth the trouble.  Not only are they faster than sandpaper in many situations, but the final finish is better, better in a couple of ways; since the wood fiber is sheared cleanly rather than sanded to a fine pulp the grain appears clearer and deeper, and since the grain isn’t filled in with fine dust the wood accepts stains more readily.  You would have to look at a finished, properly scraped wood surface to see the difference.  And, best of all, its done by hand, quietly and skillfully.