Ron Hock's Sharpening Notes...
Tips on Keeping Your Blades Sharp!!
I finally got around to writing my own instructions
for sharpening after using a reprint from Woodsmith Magazine on our blade
wrappers for over twelve years. I heartily thank them for their generosity
but I always wanted to use my own words about techniques that work for me. These
same notes now appear on our blade wrappers.
I also recommend Leonard Lee's The Complete Guide to
Sharpening from Taunton Press and Brian Burns' Double Bevel
Sharpening from Palo Alto Publishing. You can't have too much information.
Can sharpening be fun?
woodworkers find the sharpening process a pleasant pre-work meditation,
most of us would just as soon get it out of the way and get busy woodworking.
There is more to sharpening than I can cover here and I refer you to any of the
many excellent books on the subject. What I offer here, in extremely condensed
form, are some ideas and methods to help make the task less forbidding.
First, The Goal: A sharp edge only exists where
two planes (i.e., the back and the bevel of a plane iron or chisel, or the two
bevels of a knife) meet with zero radius. Of course, "zero
radius" is a theoretical ideal that eludes us as we move to the next, more
There will always be some radius to an edge but The Goal is to minimize it. (Our
fine-grained steel helps you here; the hardened particles in our steel are very
small, allowing a smaller radius to be sharpened.)
Next, Getting There: Any of the popular abrasive
devices can and will sharpen your blade. The choice is yours. The venerable
"Arkansas" oilstones are legendary and keep their shape and flatness
with little maintenance. These are a natural, quarried product that will last a
lifetime. Man-made waterstones were more recently introduced from Japan, having
a long history there as a natural stone. These stones sharpen more quickly
because they are softer and thus wear faster, exposing fresh, sharp particles as
they wear. However, their softness requires they be flattened often to avoid
their tendency to "dish," which makes accurate blade flattening and
Many woodworkers use a series of
sheets of wet-or-dry sandpaper as their abrasive medium. A piece of glass serves
as a flat base-plate and the sheets are simply switched as the blade is honed
through successively finer grits. The low start-up expense, ease of use, and
variety of grits (up to 2000-grit or finer from the auto supply) make this a
great way to get started. Then there are diamond stones (great for coarser
work), lapping plates (those who know them, swear by them), ceramic stones,
leather strops (excellent for final finishing), and an overwhelming selection of
powered machines all designed to make this task easier. Whew!
If you have a method that you
like, that works for you, stick with it, use it. The following steps are
mostly generic and you can follow along regardless of your abrasive proclivity.
If you're new here and "grit-less", head to the store that sells
automotive paints and related supplies and buy a sheet or two each of 180-grit
(180X), 320X, 400X, 600X, 1200X, and 2000X. Some folks like to use 3-M #77 spray
adhesive to stick down the sandpaper sheets; they sell it where you buy the
sandpaper. Next, to the glass shop for a piece of 1/4" glass about a foot
square. A marble floor tile, or scrap piece of monument or countertop granite,
works well, too. Now go clear a spot on a workbench for the glass or tile.
With a new blade, start with the 600X paper. If the back needs a lot of
flattening, don't be afraid to use a coarser grit to save time. When
resharpening a blade, if the edge is chipped or horribly dull you may need to
start coarser: 320X or 180X may be necessary.
Honing guides are useful things. If you have one, now is a good time to use it. Most block and
bench plane blades are ground to 25° but some smart folks argue that there need
only be clearance under the heel of the bevel. In other words, since the average
bench plane blade is bedded at 45°, any bevel angle less than that will provide
the needed clearance. And a thicker bevel is stronger so the edge should last
longer. Bench plane and block plane blades have traditionally been beveled to
25°. Our blades for the handmade wooden planes were specified by James Krenov
to have a 30° bevel. Chisels get different bevel angles for different tasks:
25° or lower for paring, 30° or so for chopping. Experiment a bit with
different angles to see which one works best for the wood and your style of
A honing guide helps with all this by establishing an angle and sticking
to it. It can also shorten the whole process by letting you raise the blade a
degree or two so that you're only honing the very edge. The angle of the bevel
is determined by how far the blade sticks out of the honing guide.
At least one brand tells you right on it how far to extend the blade for a 25°
or 30° angle. If your honing guide doesn't tell you how far to extend the
blade, you'll have to experiment and measure to get what you want.
No honing guide? That's okay,
but you'll have to exercise a bit more diligence and control while honing the
bevel. It is important that the bevel be maintained throughout the sharpening
process. If you rock the blade, the bevel will end up convex, "roundish,"
and the actual angle at the sharp edge will be greater than you intended. Not
the end of the world, but it makes apples-to-apples comparisons between woods,
steels, tools and bevel angles impossible. You can cut an angle template from a
piece of cardboard, or whatever, and use that to check the angle as you go.
Start by "grinding" the bevel until a burr forms on the
back. It may not be very visible, and will get smaller as you move to finer
abrasives, but the burr will catch your fingernail. If the edge radius is large
(which is a fancy way of saying "if the edge is really dull"), it may
take a while before the burr will appear but it must be there or you haven't
done enough work. It's the burr that tells us when the two planes have met (that
zero radius thing, again.)
Now flip the blade over to do
the back. Flattening the back is as important as honing the bevel. I repeat:
Flattening the back is as important as honing the bevel. Think about it:
in a bevel-down
plane, like all bench planes, the back of the blade is the
cutting edge. So you have to make the back flat to insure that the
edge is straight, smooth and sharp - without waves, valleys or
"teeth". Many woodworkers believe that the whole back, from the edge
to the slot, should be flattened and honed. Others figure that a stripe about an
eighth of an inch back from the edge is sufficient since the chip breaker rarely
exposes even that much. Your choice.
If you can leave the honing guide on
the blade, just hang it over the edge of the stone or plate. If it's in the way,
you'll have to measure and reset the blade extension from the guide each time
you change grits. Start with the coarse abrasive you've been using and rub the
back using even, firm, down-pressure and take even, steady strokes keeping the
blade flat on the surface. Do this until your scratches are uniformly all
over the area you want to hone. It's quite common for a plane blade to have a
slight "hollow" in the back and the early honing will reveal an arc of
fresh metal along the edge and sides. You can expand this area as far as you
want until the whole back is covered with the coarse scratches. When you're down
far enough, and the planar surface of the back meets the planar surface of the
bevel (zero-radius!) you will raise a burr on the bevel side. You're there.
Change to a finer grit and
repeat the above process. Once the back has been ground flat with the first
grit, it gets much easier and goes much faster. It's a good idea to angle the
blade slightly while working on the back and to change the angle with each
successive grit. That way, you can readily see when you've honed off all the
scratches left by the previous grit; another clue that it's time to change to a
Check the blade to be sure that it is staying square. If it's not, push a
little harder on the high corner while honing the bevel to bring it back square.
Proceed through the grits until you run out of them. After a few, the honed
surfaces will begin to act as mirrors; a sure sign of imminent sharpness.
For most efforts, the 2000X paper is
as fine as you need to go. But if you're doing the final planing on a surface
that you don't want to degrade by sanding, you may want to go beyond the 2000X
paper to a 6000X waterstone or a strop charged with chromium oxide compound
("green oxide" or "knifemaker's green"). The 6000X
waterstone is a soft "stone" of cerium oxide that cuts fast but can be
tricky to use because the blade wants to stick to the fine surface. Slow
strokes, plenty of water and patience are required. The strop can be leather,
cardboard, or wood; a flat, fine textured surface that will take the crayon-like
super-fine abrasive is what you want. It's best to gently pull the blade across
the strop or you risk cutting into it. Be careful to keep the back flat against
the stone or strop and the bevel at the correct angle; you don't want to round
off the edge.
To test for sharpness, you can
always shave the hairs on your arm (or wherever). A sharp edge will cut hairs
with very little pressure. But if you're running low on hair (or just hate that
patchy look) there are other ways. A sharp edge will catch on the flat of a
fingernail or plastic pen barrel while a dull edge will skid a bit. It's really
that simple; try it a few times to feel it but it takes only the lightest touch
and if it skids, it's dull.
Also, you can see if a blade is sharp. Closely examine the edge with good
light and if the edge reflects at all, it's dull. (Remember that zero-radius
stuff? It's the blade's edge radius that reflects light and if there is no
radius -- The Goal -- there will be no reflection.)
If you've just done a chisel,
block-plane blade or other breakerless blade, you're done! But if you're
working on a bench-plane iron, you're not done until you've polished the breaker.
Make sure the breaker, when tightened in position on the blade, makes complete
contact along its edge with no daylight showing; no gaps at all where a shaving
could catch. Now polish the breaker ramp-surface. How much work is needed
depends greatly on its condition, of course, and how smooth is enough is a
matter of experience and performance. Use the same abrasives starting no coarser
than you must. Breakers usually aren't hardened so the work should progress
quickly. Rock and slide the breaker along the different grits until all coarse
scratches are gone and the ramp area looks and feels smooth. Now you're
Resharpen often and lightly,
no coarser than necessary, to insure good cutting performance and save time in
the long run. Good luck, have fun, and... "Ommmm"
Hock Handmade Knives
For more information about the finest replacement blades for hand planes and more,
visit Hock Handmade Knives at http://www.hocktools.com