All
About Rasps and Rifflers in Woodworking
To see our entire
range of Auriou rasps click here
To see our entire
range of Gramercy rasps click here and here
For Nicholson rasps click here
For
more information on the history and design of rasps, click here.
A rasp
is a piece of steel with little teeth cut in all over the surface of
the tool. Rasps superficially resemble files, which have long teeth
running the width of the file. Files are
very useful and popular tools, but their woodworking use is mostly restricted
to sharpening woodworking tools. They're basically used for metalwork,
whereas rasps are used on wood and stone. (Occasionally you encounter
a woodworking "file," - just to make it interesting - but
typically that tool has teeth like those on a rasp.)
We use
the word "rasp" to denote the entire family of the tool when we're talking
generally about the use of the tool. When the particular details matter,
we say "rasps" to mean a rasp with a handle at one end. We use the term
"riffler rasp" or "riffler" to describe a type of rasp with teeth cut
in both ends, with an area to hold onto in the middle. Rifflers can
be either "file cut," with long lines of teeth, or "rasp cut," with
pointy teeth. "Riffler rasp" might be the better term to use. Chances
are if you were to go into a general tool store and ask for a "riffler,"
they would sell you a riffler file.
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Most rasps
made these days are machine made. Consequently the teeth are in regular
rows, one behind the other. What this means is that the rasp will cut
little troughs and not leave a smooth surface. The solution to this problem
is to slightly vary the tooth position so each row of teeth cuts a slightly
different path. This leaves a smooth surface. Rasps made in this fashion
are known as Patternmaker's rasps. The only rasps of this sort currently
made by machine are the American made #49 and #50 Nicholson rasps that
we stock. Auriou in France still makes a huge variety of rasps by hand,
using the same techniques and attention to detail that they have for amost
170 years. For more information on the manufacturing process
click here..
Roughness
With only two patternmakers rasps left in the Nicholson range, all you
need to know is that the #49 is slightly coarser and cuts a little faster
than the #50. The Auriou rasps have a much more complete grading system.
The process of cutting the teeth on the rasp is known as "stitching" and
the finess of the rasp - the size of its teeth - is known as the "grain."
Auriou rasps range from #1 to #15 grain. A #1 grain rasp is very, very
coarse, and the #15 grain is the very finest. In general, the very coarse
rasps aren't used in woodworking, and are mostly in demand by stone carvers.
Woodworkers are mostly interested in grains #9 to #15.
The cost
of a rasp is related to the number of teeth it has. See the photograph
on the left (actual size) to see what all the grains look like. What is
important to note is that the finer rasps have a greater density of smaller
teeth, not fewer larger teeth. Lower quality hand-made rasps will have
uneven teeth, which will cut slower and leave scratches.
The teeth
on the Auriou rasps are handed so that you can work more comfortably.
See below for more information.
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Shape
Auriou rasp
come in many different shapes: flat, round, curved, straight, etc. The most
popular rasps are the cabinetmaker's rasps. Some important features are
shared by all the styles of rasp. The flat side of a machine-made rasp is
always flat, but the flat side of a hand-made rasp is always slightly convex,
which makes it far easier to rasp a flat surface. Rat tail rasps are slightly
bellied for the same reason. French Cabinetmaker's rasps come to a point.
Machine made rasps have the point cut off. On Auriou rasps, the teeth go
out to the edge of the rasp. This feature allows you to cut into a sharp
corner. On Nicholson rasps the teeth are a little inset from the edge, which
means you cannot work a clean inside corner.
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Riffler
Rasps
There
are 8 traditional styles of riffler rasps (1-8 starting from the top
of the picture). The choice of what shape is at each end comes from
a long tradition of patternmakers who, working quickly
wanted a complementary shape on each end of the riffler. It is far faster
to flip a tool around than it is to put down and then pick up two different
tools. The eight styles of riffler are all available in different lengths
proportional to the coarseness of the grain. In addition, the length
of the blade (the cutting surface) is proportional to the overall length
of the rasp. You should select the rasp based on the size of the work
you are doing. All the Auriou rasps leave a smooth surface, so the marginal
improvement of a finer grain isn't as important as the extra speed you
get with a coarser grain and longer blade.
Auriou
riffler rasps have a smooth octagonal center section that is easy to
hold in position and more comfortable than a square. The shapes are
also extremely graceful and visually appealing. The rifflers have gentle
curves; they're not just bent in the middle. The oval shapes are true
ovals, not just flats that have been rounded off. All of this adds to
a rasp that performs solidly and cuts predictably throughout the entire
stroke.
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Usage
Rasps are a shaping tool and are designed to quickly remove wood, leaving
a smooth surface ready for final scraping and finish.
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rasps must be handled for use. There are two important reasons for this:
first, if the rasp does not have a handle, you will tend to grasp it on
the lower part of the teeth. This is not only a great way to cut yourself,
it wastes half the stroke of the file and makes every cut take twice as
long. The second reason is safety. If the rasp were to catch while you were
filing, the tang could punch its way though your hand. So please use a handle.
All of our Auriou rasps come with handles already installed. All our Nicholson
rasps are available with top quality Scroozeon handles which can be reused
for years on different files. |
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teeth on Nicholson rasps are perpendicular to the handle. The teeth on Auriou
rasps are slightly angled to favor right-handed users. If you are left-handed,
please contact us as we can order you left-handed rasp (although we do keep
some in stock). The reason has to do with the proper use of a rasp. |
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rasp should be grasped by the handle in one hand. This is where the power
behind the rasp comes from. The other hand should grasp the tip of the rasp
in thumb and forefinger, to balance the pressure on the stroke and to give
control. The teeth should be perpendicular to the direction of the stoke.
This means that with a Nicholson rasp, you hold the rasp square to the work.
Auriou rasps are handed, so you hold them at an angle to the work but push
them perpendicularly to the work. See the diagram below for clarification.
The reason for this is that it is more natural and easier to hold the rasp
at an angle to your body, which lets you stand closer to the work, giving
you more leverage. The exact angle varies but you will find your own sweet
spot fairly quickly. |
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| Use
the rasp in a long and smooth forward stroke. It will cut very fast. At
the end of the stroke, lift the rasp off the work and retract it for the
next stroke. The rasp only cuts on the forward stroke. Do not pull back
with the rasp against the work, as you will in time dull the rasp prematurely.
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Storage
and Cleaning
When you
are done with a rasp, use a brush to clean and unclog the teeth. Don't
use a file card made
of wire (steel or brass), that will dull the rasp in time. Michel Auriou
strongly cautions against this and suggests a short (3/8" long) stiff
natural bristle brush. He also suggests that after cleansing, a light
coat of camellia oil should be applied to protect the rasp from rust.
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| We
use the term "French Rasp" and Auriou almost interchangeably.
This is because Auriou is the last full range French rasp company still
making rasps in the old tradition. For more information on the history
and design of rasps, click here. |
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To see
our entire range of Auriou rasps click here
For Nicholson rasps click here
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