Deciding which Sharpening Strategy
The
problem with sharpening threads on forums is that they all end up the
same way - a million different methods and recommendations ...
proving that everyone is wrong and I am the only one with the secret
to the right way to do this!
When
deciding on a sharpening strategy, it is important to consider the
type of steel you are sharpening. The softer steels, such as O1
(including laminated blades, even the Japanese with very hard cutting
layers) can be honed on the full face of the bevel. However the
harder and more abrasion-resistant steels, such as A2 and PM-V11,
really need to be sharpened with a microbevel. The microbevel may
either be a tiny secondary bevel or it may be a product of honing on
the face of a hollow grind.
Generally, secondary bevels are
easier to do with a honing guide if you are starting out, or if you
have no intention of developing the handskills involved. With the
latter, lifting the blade a couple of degrees as you move to the next
higher grit, requires some practice to achieve relative accuracy, and
for this reason fewer stones are preferred (less error
involved).
For those freehand honing directly on the hollow,
as I do, the process is made quicker if the hollow is done well. The
best hollows are those that leave very little steel to hone, and the
edge is straight. A straight edge may not require a coarse stone (eg
1000 grit) to straighten it before moving to a middle stone (eg 6000
grit).
The process is similar when using a honing guide: a
straight primary bevel can be more easily converted to a secondary
bevel with a middle stone if there is little work to do. This is why
grinders such as the Tormek, belt grinders, and dry grinders with CBN
wheels score so highly - they leave a cleaner and straighter primary
bevel. Tormek blade guides, and similar blade holders, such as the
Veritas, also facilitate a straighter grind and edge. Excellent work
may be done freehanding and with white and pink wheels, but these do
require more hand skill.
More commonly, for those
starting out, the magic bullet is not a great grinder or the best
honing guide or the stones one uses. The magic bullet is knowing what
to do, and what to do is to create a wire edge each time you hone a
bevel (whether primary, secondary or tertiary). That is a guarantee
that you are honing to the edge of the blade, and that is what you
MUST do to create a sharp edge. All the above comments are geared
towards achieving that wire. Anything less and all you are doing is
polishing above the cutting edge. It looks pretty but is
dull.
Honing on a full bevel is easiest when the steel is
soft, and this is especially important if using the slower cutting
media, such as oil stones. I included laminated Japanese blades in
this category since the backing layer is often very soft cast iron
and the hard cutting later is very thin - essentially the same deal
as a honing on a secondary bevel.
Paul Sellers once posted a
confronting video in
which he sharpened plane blades with a 250 grit medium. The planes
cut. Some (like myself) commented that this was not a true
representation of sharpening needs, that is, the wood was soft and
straight grained. But the point is that even a low grit can do the
job. 16000 grit waterstones are not automatically the answer.
The
other recommendation is that what ever you use, use it for one year
before you make any further changes. It takes time to get the best
out of something.
For the record, I mainly use a worn 600 grit
diamond Eze-lap diamond stone (which does not get used until the
third honing - and can be delayed longer if I use my hardwood strop
more frequently before the blade dulls appreciably), Medium and
Ultra-Fine Spyderco ceramic stones, and end with Lee Valley green
compound on a hardwood strop. I hollow grind on a 180 grit CBN wheel
on a half speed dry grinder. This system has been in place a few
years now and I have not wished to change it.
Regards from
Perth
Derek
July 2017