Rasps, Files, Rifflers and Floats

These are handy tools for shaping wood.  While some files are meant only for metal they can be used on wood.  But wood files, rasps, rifflers, needle files and rasps and floats are made exclusively for shaping wood.  I will go through the different types and talk of different cuts and names for various methods of referring to these tools.  These tools always work better when they are used with the grain of the wood.  End grain wood is worked from the outside to the middle to prevent chipping out.  You will notice that filing or working in one direction on end grain works better than the other and some difficult end grain is best worked across the end grain against the direction of the grain in the end grain. Both rasps and files come in a variety of shapes.  Round, square, triangular, flat, half round or combination such as flat on one side and half round on the other (called cabinet rasps or cabinet files) are common shapes that are available.  Special knife-edge files or rasps and other shapes made for different applications.  Most files and rasps especially the flat ones come either blunt or tapered.  The blunt being the typical file shape and the taper design going to a ‘point’ is handy for getting into tight areas.  If a files or rasp have no teeth on one or more edges it is said to have a ‘safe edge’, that does not cut.  When lengths are given they do not include the tang.  The tang is the thin pointy projection from the end of most files and it is a good idea to have a handle or handles for your rasps and files.  It is not a good idea to permanently install a rasp or file into a handle.  The handle needs to be periodically removed for particular filing or rasping applications and you will want to be able to remove the handle for cleaning and sharpening.

It is interesting to note that the Native Americans used rasps and files that were traded from the invaders, but they also found a different application.  Many wooden artifacts of the post contact era were decorated with files and rasps that were heated up in a fire and used to brand the tooth pattern into the objects.

Rasp – The rasp is an aggressively cutting tool with sharp teeth in the surface that act like a series of small gouges and tear the wood away with a minimum of work.  The teeth are cut one at a time using a cape chisel to raise each tooth and then heating and quenching harden the file.  There are coarse shaping rasps that hog out wood quickly and fine cabinet rasps for smoother wood removal.  Quality rasps have random teeth, loosely following a pattern and these types of rasps produce smoother cut.  A fine grade of rasp is called a cabinet rasp; with fine teeth it produces a relatively smooth finish that is easily smoothed with a file or scraper

File – The file has finer straight teeth usually cut at an angle, sometimes cut at two angles that produce a series of fine cutting blades that produce very smooth results.  These are cut by hand using a straight sharp metal cutting chisel in fine parallel lines, the file is then heated and quenched to harden.  The file removes less than the rasp but produces a smooth finished end product.  Files come in two general cutting patterns: the first is single cut, these are parallel teeth cut into the file at an angle to the length of the file.  This type of file produces the smoothest results.  Double cut has the same pattern as single cut but then a second set of teeth is cut at the opposite angle producing a rougher and coarser tooth pattern.  Double cut files are more aggressive and are not a smooth as single cut.  There are several distinctions between these two cutting types depending upon the coarseness or fineness of the cut.  Coarse is usually a large tooth double cut and removes the most wood and leaves the roughest surface.  Bastard cut is also a double cut pattern and produces an aggressive cut but leaves a smoother surface.  Smooth cut is usually a fine single cut tooth pattern that produces as the name implies a non-aggressive yet very smooth cut.  There is also a finer version called the dead smooth cut and the name tells it all.

Riffler – Rifflers are either rasps or files that are smaller and usually shaped and are placed at the ends of a forged handle where these small tools are gripped.  This usually means that you get two tools, one cutting head at each end of the handle.  Used especially for carving and smoothing delicate intricate work.  Follow the same procedures for using, cleaning and sharpening as you would with a regular file or rasp.  Besides the advantage of being able to get into tight areas, the handle of the riffler offers a convenient place to hold the tool but also provides good control for the tools use.  When you get a selection of rifflers, keep them where they will not bang into each other dulling the teeth.  A block of dry wood with holes large enough for the heads and spaced so the other ends can’t touch each other is a good way to store rifflers.  Because of the delicate points on the ends of rifflers, take care when using, it is quite easy to snap them off.  Never force or pry with the riffler.  Properly hardened, the handles will be softer but the heads can be quite brittle because of the necessary hardness required for the teeth to do the cutting.

Needle Files & Rasps – These are miniature versions of rasps and files with straight handles instead of tangs.  They are used for more delicate and smaller intricate work.  While these tools are handy, they are subject to breaking, so use caution and a gentle hand when using these handy tools.  I have made a set of miniature chisels from old broken needle rasps and files, they are usually made of quality steel.

Float – The float is like a file but with much larger teeth.  There can be as few as 4 or 5 teeth per inch and the tool acts like a very wide rip saw but produce incredibly smooth finished results.  The teeth act like plane irons or chisels and produce very fine shavings.  These are perhaps the most obscure of the rasp / file group.  It was mainly used by plane and toolmakers to shape the hard beech that many of these old planes are constructed.  In particular the throat that holds the wedge and blade.  These angled mortises have much exposed end grain that needs to be made perfectly flat and at an angle to accept the blade and the wedge that secures the plane iron.

Using – Files and rasps are made to use only in one direction, the opposite of the point of the tang.  Using files backwards, yes they will cut somewhat, but this will dull the file as the teeth will be rounded over, they are not made to be used in this manner.  Take full long strokes with the file or rasp, do not just concentrate your use in one area of the tool, use all of its cutting length.  Start shaping with coarse rasps then move on to finer cut rasps and then on to double cut file and then to a single cut file or float.  Files are particularly useful on end grain.  But remember use them only on the push stroke, don’t even drag it back over the work, lift it up and place it down to avoid excessive wear on the teeth.

Cleaning – The standard method of cleaning files and rasps is to use a file card.  A file card is a flat piece of wood with steel teeth set in a binding material that is attached to the wood handle.  The teeth are the same material used in wool cards to prepare wool for spinning.  A wire brush will also work, I would recommend using a brass wire brush as a steel one will tend to dull the teeth.  Another method of cleaning is to immerse in water and the wood in the teeth will swell up and come out easier.  The file or rasp should be dried thoroughly to prevent uneven rusting and pitting from occurring

Sharpening – While there is nothing quite like a brand new file or rasp, used files and rasps can be sharpened to a certain degree.  The nature of the steel in the file and the shape of the teeth allow for a rather simple method of re-sharpening old files and rasps.  The method is to first clean any debris from the teeth and clean any oil or grease from the surface with alcohol or soap and water.  Once the metal is clean it is placed in a bucket of salty water or brine.  All of the teeth of the rasp or file should be immersed in the brine, the tang or handle does not need to be in the solution.  What happens is that the steel of the file or rasp begins to rust.  The metal at the teeth will rust more on the flat parts of the metal than on the edges.  Consequently the file or rasp teeth are actually sharpened.  While they might not be as sharp as when new, this method will get extra use out of tools that are far too frequently discarded.  Remember when a file or rasp is all used up and can no longer be sharpened, it is an excellent source of fine steel that can be made into other tools such as turning chisels and plane blades.  The traditional method of sharpening was to soak the files or rasps in a bucket of urine, which makes the best sharpening solution.