Skate Sharpening for Figure Skaters
Frequently Asked Questions
Your blade can be your best friend or your worst enemy. Whenever
you skate, you trust your personal safety to it. It is the origin of
every force that drives every movement that you make. If you intend to be a good
skater, you need to know it like an extension of your body; how it feels
and how to use it. You need for it to work the same all the time, so
you may find it useful to know something about how it works.
I feel that there is generally too much mystery surrounding skate
sharpening. What constitutes a good sharpening job is not mysterious
at all. I hope that these questions and answers will clear up some of
In the following, I have tried to base my discussion on sound scientific and
engineering principles, and whenever something is my opinion, I will state it
Q - Why does the blade slide on the ice?
Water has the uncommon property of expanding when it freezes. This
is one reason that you need antifreeze in your car. It is also the reason
that ice cubes and icebergs float (and why the Titanic sank). If you apply pressure
to ice, it melts. So, when the blade presses against the ice, it creates a thin
film of water which acts as lubricant, and allows you to slide. When you are skating,
you actually are sliding on a thin film of liquid water. At least this is the
commonly accepted theory (some recent research has disputed this.)!
Q - Why does the blade turn when I lean?
Next time you skate, glide straight ahead on a flat. Using your ankle
and nothing else, tilt the skate to the right or left, and feel how it
turns you in that direction. Look at the shape of the blade. Viewed from the side,
it curves up at the front and back (it has "rocker"). Pressed into the ice,
a short length of it is actually in contact with the ice. As it
is tilted onto an edge, you can probably envision that this length of contact
is slightly curved. As the blade moves along the ice, it will follow this curve.
The curve will be deeper if you lean your ankle more. It will also be deeper if
your blade is more strongly rockered, as most blades are toward the front. As you glide
on an edge, press slightly forward on it, and feel how it tries to curve more.
Q - What is the hollow?
A - You probably know that your blade has two edges, inside and outside,
and that there is a "hollow" between the edges. You may also know that the
hollow can be "deep" or "shallow", and be able to feel the difference
by running your finger across the blade.
Refer to the following figure showing a crossection of a blade. The blade is made
of a piece of steel of some thickness (a typical freestyle blade is about
0.15" thick). The bottom of the edge is ground out with a circular cross-section
(see "how is a blade sharpened", below). The radius of the circle is called the
Radius of Hollow (ROH). The shorter the ROH, the "deeper" the hollow. A blade
with a deep hollow will hold the ice better, but will also be grabbier and
Q - What is the correct ROH for me?
A - This is a very individual matter. I will state some facts, and then
An important thing to note is that ROH does not tell the whole story about
how a blade feels. The blade touches the ice only along the edges, so what's
really important is the angle between the side of the blade and the bottom of
the blade at the edge. Some blades are wider than others. Whereas an MK Phantom is
0.155" wide, an MK Dance is only 0.11" wide. If you have a geometric mind, you
can probably see that, given the same ROH on the two blades, the wider blade
will have a sharper angle at the edge. So, to give the same strength of edge,
narrower blades will need a shorter ROH.
A more acute edge angle (deeper hollow) makes the blade less likely
to side sideways, so a deeper hollow gives more secure edges. There is more to it than that,
though. It also makes the blade more determined at going where IT
wants to go, so it will be harder to control (more likely to grab or "catch an
edge"). And, the deeper cut into the ice causes more drag, so the blade
will be slower. Given these tradeoffs, one could state that the optimum
ROH is one which is just deep enough to give the skater the required
edge security, but no deeper.
My personal preference is
toward the shallow end. Especially for those learning to skate, I think that
learning proper use of the ankle to control edges is important, and that a
shallower hollow facilitates this. As the skater becomes more advanced,
they are likely to use a deeper hollow to gain security of edge. This may be
especially important to advanced freestylers desiring edge confidence on jump takeoffs.
On freestyle skates, I see ROHs varying from 7/16" to 5/8".
Personally, I use a 9/16" hollow on my Wilson Dance blade (0.14" wide). I am a
Gold level skater.
With a deeper hollow, you may be able to go longer between sharpenings.
The following graph shows bite angle versus ROH for various blade widths
(The MK Dance is 0.11" wide, Wilson Dance is 0.14" wide, most skates are
0.15" wide, Phantoms are 0.155" wide at their widest part). Given a desired bite angle and the
width of your blade, you can look up the radius of hollow required to give that
bite angle. A 10 degree bite angle is pretty deep, and a 7 degree is fairly
Note that on side-honed blades, the side of the blade where it meets
the ice is cut at an angle to the plane of the blade, so the bite angle
is effectively increased by this amount. On side-honed blades that I have
examined, this angle appears to be between 2 and 3 degrees. An exception
is the Phantom Special, on which the side is cut at an angle of about
9 degrees! Note that the geometry is slightly different for this case,
so the blade will behave differently than one that simply has a very deep
Q - What is the rocker?
A - If you look at the blade from the side, you will see that it curves up
front and back. This is rocker. Blade companies generally specify the
"rocker radius" for their different blades. If you draw a circle of this
radius (typically 7 or 8 feet), approximately the back 2/3 of the blade
will have a fairly circular contour. The radius of curvature decreases toward
the front (there is more curve), giving the blade a complex shape.
The increased curve toward the front of the blade has an interesting
effect. If you move your weight forward on the blade while on an edge, it
will want to turn on a deeper edge. You may know that you spin on this part
of the blade. You probably have also felt how the blade can grab if you
rock back on it while spinning.
A long radius of curvature gives a faster, more stable blade. This is why
speed skates have very little rocker. It is also gives less maneuverability,
which is a reason why figure skates curve more at the front.
In my experience the rocker radius that is published by the blade
manufacturers must be taken with a grain of salt. MK blades are mostly
specified to have a 7 foot radius, John Wilson blades, 8. A recent check of
many new blades from our rink's pro shop indicated that the MK blades
were pretty close to their specified 7 foot radius, while Wilson blades
were closer to 6.
Of more concern is the considerable deviation that is seen, in the
form of local "humps" in the rockers at various points on the blade, of
both brands. Their specified radius is not precisely controlled. I even
had a serious skateability problem with Wilson Dance99 blades as
a result of a hump right in the middle of the rocker.
Of course, it is also quite possible that careless sharpening can
introduce such problem as well.
Q - What is a Dance Blade?
A - If you examine dance blades, you might notice a few differences. First,
they are short. Dancers tend to do lots of tight footwork, and the short heel
gives less to get tangled up (step on, lock with your partner's blades or
your own, etc.). Secondly, they don't tend to curve up as quickly on the front,
so they are not particularly good for jumps and spins. Also, they do not
have the pronounced toepick that is seen on freestyle blades, since they
are not expected to be used for jumping.
Dance blades are less forgiving than freestyle blades. Many dancers
have experienced getting their weight too far back and falling over backwards!
Dance blades are often narrower than freestyle blades. So far, I am
unable to deduce a reason for this design feature, and have not heard it
explained satisfactorily. They are definitely harder to sharpen accurately
because of this.
Q - What does the toepick do?
A - There are two parts of the toepick, the part that hangs down (the
drag pick), and the part that sticks out in front (the master pick). The
drag pick is the last thing to leave the ice on an axle, the first thing to
touch on a jump landing, and just touches the ice on most spins.
If you rock forward on the blade, you can only go so far before hitting the
toepick.This forwardmost point is called the "Forward Balance Point". When you
spin, you are skating on this point, with the toepick just touching the ice.
Because of the toepick, note that you cannot skate on the length of
blade forward of the forward balance point..
Q - How is a skate sharpened?
A - The skate is sharpened with a rotating grinding wheel. Prior to sharpening,
the wheel is "dressed" (using a special diamond-tipped tool) in such a way that
it has a circular cross-section (whose radius is the Radius of Hollow). The
skate blade is clamped into a holder, which holds its bottom surface
perpendicular to the grinding wheel. Your friendly skate sharpener moves
the clamped blade along the rotating grinding wheel to refresh the hollow
in the bottom of the skate. The sharpening machine has a special guide
to keep the blade perfectly aligned with the grinding wheel.
The goal of the sharpening job is to remove just enough metal from the
bottom of the blade to renew the edges. A steady hand is required, so that
no part of the blade is ground more than another.
Q - Is the toepick ever ground?
A - Yes. You can see that after a blade has been sharpened many times,
the profile of the edge will be the same, but closer to the boot. If the
drag pick has been left untouched, the drag pick will be at a different
relative position than when the blade was new, and the skater's technique
will change to accommodate this. It is therefore desirable to occasionally
remove tiny amounts of material from the pick, so that the profile is
retained. This is a tricky operation, easy to overdo.
Q -My blades aren't flat on the sides - what's the deal?
A - Generally, less expensive blades are of constant thickness, with flat sides.
As you get into the more expensive blades, you may see two features: they
may be tapered from front to back (wider at front, narrower toward back),
and they may be "side honed" (material ground from the sides so that
instead of being flat, they are concave).
Depending on the blade design, side honing may create a sharper bite
angle at the edge. It definitely makes a blade harder to sharpen with level
A blade design variation worth noting is the "Coplanar". These blades have
the high quality steel and stronger construction of high-end blades, but are
of constant thickness throughout, thus easy to sharpen well. In addition, they have a
unique mounting geometry with certain claimed advantages (because of their flat,
coplanar mounting plates, they can be repositioned on the boot without changing
the blade angle.).
Q - How often should I have my skates sharpened?
A - "When they need it". It depends on how much you skate and how hard
you skate. If your edges are damaged or no longer feel secure, then it's certainly
time. I try to remember that nice feel of freshly sharpened skates, and
when they don't feel that way, it's time.
If you examine the bottom of the blade right after sharpening, the bottom of the
blade will have a uniformly satin sheen. With more skating, the blade bottom near the
edge will begin to appear dull. As these dull bands get wider, you might want to
think about resharpening your blade.
When I sharpen, I use the fact that a sharp edge does not reflect
light. If you view the edge under a strong light, the degree that it
reflects is a gauge of its dullness.
Q - Are new blades ready to skate on?
A - Figure skate blades generally come from the factory already sharpened.
My observation is that this sharpening job is generally of low quality,
usually having a very coarse grind and rather unlevel edges. I have also
observed considerable variation in toepick height between two blades of
a pair (this leads one to wonder about the quality control in the curve
of the blade!). Also, the factory ROH may or may not be appropriate for the
I always sharpen new blades before skating on them.
Q - How can I tell if the edges are level?
A - Ideally, the centerline of the hollow is halfway between the two
sides of the blade. If it is not, one edge will be higher than the other,
and will have a sharper bite angle. If too far off, the effect will be assymetrical
edge strength (for example, inside edge grabby, outside weak), and flats that
want to turn.
Your skate sharpener should always check that your edges are level after
sharpening. Although perfection is neither possible nor necessary, large
errors are unacceptable. A common way to check this is to balance a
coin (or other straightedge) on the bottom of the blade, and "eyeball" it.
I think that this method is really too imprecise to detect any but really
gross errors. I use a miniature, precision machinist's square to check that
edges are square with the side of the blade. Other devices for checking this
are also made. Note that side-honed blades are much more difficult to
check, because side of the blade is not flat.
Q - Do nicks have to be completely removed by a sharpening job?
A - Not really. It is extremely important that any deformation of the
metal on the side or bottom of the blade next to the nick be ground
away. I observe that a slight "hole" in the edge is generally not noticeable,
and in the interest of prolonging blade life, I generally do not completely
remove large nicks.
Q - Can I sharpen my own skates?
A - A handheld stone can be used to lightly hone the side of an edge,
slightly refreshing it, or especially to remove a nick. It is rather
risky to attempt honing within the hollow by hand.
One can purchase products that contain a cylindrical hone mounted
in a guide that holds the hone centered over the hollow. There is no
reason that these cannot work, but bear in mind that the width of the
groove in the guide needs to match the width of your blade (beware of
tapered blades!), and the radius of the hone needs to match your
I see no reason why the mechanically inclined skater who can afford it
should not purchase their own sharpening machine and do their own skates.
Q - What does a sharpened edge look like?
A - If you examine a sharp edge in a strong light, you should see
no reflection from the edge, even looking with a strong magnifier.
Q - How should I deal with my skate sharpener?
A - I suggest that, once you find a skate sharpener that you like,
stick with them. The reason for this is simple. Every skate sharpening
machine has slight differences. A blade can be resharpened on the same
machine with minimal metal removal, protecting your blade investment.
You should be prepared to interact a little with the person who sharpens
your skates. Hopefully, they will be willing to discuss any problems that
you perceive. The most important piece of information that you will need to
supply is the radius of hollow that you want:
- You should know it, in inches.
- You should be able to say "match what I have" and have the sharpener do it.
- Your sharpener should keep records of your sharpenings, and be able
to tell you what you use.
Q - How long should it take to "break in" freshly sharpened skates?
A - Most skaters are conditioned to expect a bit of an adjustment period after
having their skates sharpened. The common symptom is that skates feel
"grabby": edges catch, and stopping is difficult. Skaters with newly sharpened
skates are often seen doing things like dragging their skates sideways on the
ice, running blocks of wood along their blades, etc., to dull them into skateability.
The correct expectation is that properly sharpened blade should have little or no
adjustment period. It should never feel grabby. It should simply feel more
secure. (exceptions are the cases of changes made to a blade, such as
correcting previous sharpening errors or changing the depth of hollow, or
sharpening an exceptionally dull blade).
The edge of a well sharpened blade should feel very smooth as a
finger is run along the edge: proper edge finishing will have removed the metal burrs
that can cause grabbiness, and give the edge a smooth, not draggy feel.
Be careful: a sharp blade can cut (though a well-finished blade is less
Q - How can I monitor the quality of my sharpenings?
A - First, you should be alert to any differences in the feel
of the blade after sharpening. Are your jumps or spins different?
Do the edges grab, especially one more than another?
When you buy a new blade, take a few minutes to trace its contour
on a piece of paper. Occasionally, after sharpening, compare the blade
to this contour and note any visible changes to the rocker. In particular,
if the same person has been sharpening your skates, visible changes are
something they should want to know about.
Q - How long should blades last?
A - If I have previously sharpened a blade, I find that each sharpening removes
only about 0.001" of metal (a typical piece of paper is about 0.004" thick)
on a resharpening. If there is 0.1" of sharpenable depth on
the blade when new, this means that you might get as many as 100
sharpenings out of a blade. With monthly sharpenings, this would give a blade
life of up to 8 years. Sharpenings to restore edge level will take off much more
metal. So will sharpenings to change radius of hollow. I believe that skaters
typically get much shorter blade life, for various reasons. Still, a careful
sharpener can do much to prolong blade life, and protect the skater's investment.
Larry Commerford wrote saying that he believes that my 0.001" is optimistic, and
that 0.004" or 0.005" is more realistic, in his experience. He says that he sharpens
mainly skates from precision team members, and that they are typically
pretty chewed up. I would have to agree that my 0.001" is a "best case"
number, coming from an ice dancer who babies his skates.
I have seen some skate sharpeners "flat grind" a blade before sharpening it.
This practice will obviously do much to much to shorten blade life.
Q - What are common sharpening flaws?
A - While the goals for good sharpening are quite easy to quantify,
skate sharpening is a manual operation, and as such is very much a "craft".
The most often seen flaw is unlevel edges. If the centerline of the grinder is
not aligned with the centerline of the blade, one edge will be higher
(and sharper/grabbier) than the other. The effect of this is that one edge
will grab while the other seems weak. If really bad, a flat will pull to the right
To achieve an even grind, the sharpener must move the blade along the rotating
wheel with constant force and speed. With time and repeated sharpenings,
it is inevitable that errors will accumulate, and show up as uneven rocker.
The degree to which this happens is a measure of the skill of the sharpener.
Sometimes a particularly heavy hand in sharpening can alter this curve in
Q - Where can I read more about blades?
A - An excellent reference is the publication "Skateology", written by
Sidney Broadbent, and available from
Iceskate Conditioning Equipment, Co.
5265 West Quarles Drive
Much of the information contained in these Q/As comes from this manual.
If you are reading this on the web, you may be interested in
investigating the relationship between ROH, blade