Robert Sorby varekatalog Robert Sorby catalogue 2018-2019 | Page 52

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Sharpening
Sharpening tools is an integral part to all woodworking. Blunt tools are not only dangerous, but they also
make hard and laborious work of what should be a pleasurable activity.
Since the early days of steel production efforts to improve sharpness and
edge retention have manifested themselves in a range of new materials
and treatments. Many of these claimants have flooded the market in recent
years. Powdered metallurgy, cryogenic tempering, A2 and M2 are just a
few of the materials available to woodworkers the world over. All of these
possess their own strengths and weaknesses.
For example, cryogenic treatments can work on large sections of steel
but after many controlled cutting tests we have found no advantage
whatsoever on smaller sections such as turning tools. Powder Metallurgy
is a similar story where again after rigorous testing we were unable to get
any significant extended cutting life from the tool, this also showed a loss in
tensile strength against traditional
raditional M2 with the correct heat treatment.
Despite all these new materials,
aterials, traditional steels still continue to thrive
and be used for the manufacture
ufacture of woodworking tools. Here at Robert
Sorby, we believe these traditional steels, with a touch of the new, can
offer clear advantages over
ver these alternatives.
Robert Sorby uses a traditional
itional modern day carbon steel for the production
of its bench chisels, upon n which a variety of hardening and tempering
processes are used. These
se will be specific to each individual chisel. Every
Robert Sorby chisel is hardness
rdness tested before it leaves the factory to ensure
it is correctly hardened and
nd tempered to give the woodworker the best
possible working edge. You
ou can see the hardness mark just behind the
cutting edge. Carbon steel
el has a very fine grain structure that allows the
production of a cutting edge
dge which can be sharpened to better than 0.5
micron. To you and me, that is four times sharper than a razor blade.
Turning tools began life being made from carbon steel, offering the
woodturner an extremely sharp edge to slice through the wood fibres.
However, for turning tools,
s, that sharpness has a weakness; it is unable
to retain the sharp edge for very long, making sharpening an often highly
repetitive process (on an 8" x 4" deep bowl, a bowl
gouge will need to cut for r 8 miles to complete
the bowl). Robert Sorby were the pioneers
of M2 high speed steel (HSS)
HSS) for the
production of its turning tools. This
material has never achieved
ved the
heights of sharpness given
en by
carbon steel due to its grain
rain
structure, but that slight
loss in sharpness is heavily
vily
outweighed by the edge
retention HSS achieves. This
enables the woodturner to
remain at their lathe with h a sharp
edge for longer periods. Robert
Sorby has stayed in close e
contact with material
developments, and the Robert Sorby Excelsior range is witness to that as
the HSS blade is coated in titanium nitride. This coating enhances the sharp
edge of the blade and allows it to stay sharp up to four times longer.
Having sharp tools is only part of the equation, knowing what they are
made from and how they are made is of equal importance when sharpening
your tools. A cutting tool is all about the best balance between hardness,
toughness, and edge retention. Too hard and it becomes brittle with little in
the way of toughness, too tough and we have to compromise hardness and
edge retention. Robert Sorby have been making cutting tools for over 200
years. How many other manufactures have the confidence to offer a lifetime
guarantee?
Every cutting tool we sell:
• Is hardness tested before it leaves
the factory.
• Comes with
a lifetime
guarantee.
• Is manufactured in our own
factory in Sheffield, England.
• We don’t just brand it Made
in Sheffield it is made in
Sheffield, England.