Modifying Skate Fit and Balance:
Blade & Balance
Some of the comments here assume that your sharpener is expert enough to reshape
your blade profile - especially the sweet spot of your blade. And perhaps to grind
off the end if it is too long. That isn't a big deal, but many, perhaps most
sharpeners aren't at all that competent. You are often lucky to find a sharpener who
doesn't accidentally change the shape of your blade, or takes off so much metal
every time that you need a new blade every few sharpenings. The only option for some
people is to get a blade whose initial shape and size works for them. Unfortunately,
for many people, that means buying several expensive blades until something works
right. If you've a good coach, they may be able to give you a good guess, but their
own foot shape is probably different from yours, so that doesn't always work.
Fitters are told to select the blade length and mount position by the boot outsole
length and position, but there is usually no reason why that should happen to be
best for you, and makes no sense whatsoever.
As far as blade shape and length, where the blade
sweet spot (the cusp where the long-wise "rocker" curvature changes - but be warned that not everyone uses that definition) is relative to
the ball of your foot matters, and how easy it is to reach your toe pick. If the
sweet spot is just a little bit forwards of the ball of your foot (where it bends),
which makes it easy for you to control motions back and forth across the sweet spot,
and the toe pick feels like it is where you want it to be, then the blade is right
for you. But you have to be able to feel where your sweet spot is to take full
advantage of it - so if the other things check out, ask your sharpener to work on
that. The blade length therefore the position of the back of the blade matters if
you lose balance, or if you tend to accidentally cross step one blade on the other.
Two great pages on blade shape that among other things explains the relationship between the sweet spot and your foot shape are
Scarlet Skater: Choosing Figure Blades
and
Scarlet Skater: Figure Skate Blade Profiles
A good sharpener can emphasize the sweet spot (make
it a sharper transition or make it change directions a little), to make it easier
for you to find. He/she can also move the entire blade forward and back to play with
the toe pick position.
Things Affecting Balance
I herein summarize other sections pertaining to
balance.
1. As mentioned on a prior page, if your foot isn't
as tight as you can stand, without hurting or squishing your toes together, the boot
may be too loose, by size or by lacing, so you tend to lose control of what the boot
is doing - in which case you need to tie the laces tighter, or add stuff inside to
take up space. It may also be too tight or loose in specific points; that too was
discussed on a prior page.
2. I would look first at whether it is equally easy
to reach an inside or outside edge before you have put much weight on the foot.
(Test all 8 edge combinations of inside and outside, left and right, forward and
back: LFI vs LFO, RFI vs RFI, LBI vs LBO, RBI vs RBO.) In particular, I want the
relative height of the left and right sides of the insole to be such that when I put
my foot on the ice, it naturally places the edge in the middle, between the inside
and outside edges, and I want to have equal pressure on the left and right sides of
the bottom of my foot.
We have already discussed taping and shimming to equalize pressure on prior pages.
E.g., if your foot is easier to put down initially
on an inside edge than an outside edge, stick tape underneath one side of the
insole. I think that for most people, you would stick the tape on the bottom of the
insole underneath the inside edge of your foot. (However, for reasons I don't fully
understand, some people find it works better to stick the tape on the bottom of the
insole underneath the outside edge of your foot, so try that too.)
(Also, if it is easier to put down initially on an
outside edge than an inside edge, reverse "inside" and "outside" in the above
discussion.
The front and back of your foot are different, so
you can use a different taping front and back to reach both forward and outside
edges symmetrically.
Note that shimming - i.e., placing tape between the
outsole of the boot, and one side of the blade mounting plates, has almost the same
effect - but may be better if there isn't enough space inside the boot for tape
under the insole, and your foot feels too tight.
3. Is it equally easy to hold inside and outside
edges in 1-foot glides once the initial edge has been placed?
Many people have one or both feet collapse
asymmetrically as they put weight on them. If it is substantially easier to hold
inside edges than outside edges while gliding on one foot, your blade may be mounted
"wrong", for moves beyond the first several lessons, as many (perhaps most) beginner
blades are. What you probably want to have happen is for the foot to naturally hold
the edge that you initially put it down on. Offsetting the mount to the inside may
make your weight tend to shift to the outside, as you put weight on it, which is
what you want.
The front and back of your foot are different, so
you can use a different sideways offset front and back, so you can hold forward and
backward edges.
4. If your boots and blades are set up to make you
naturally symmetric, and it is still hard to hold your outside edges, then body
posture, muscle strengthening, and lots of practice, are all you can do.
Further Balance Info
You should feel comfortable skating balanced over one foot.
Check your balance while skating on one foot glides. (But some coaches prefer to
balance on
two feet, because they spend most of their time that way.)
Make sure you do not need to use muscles on one side more than the other of your
foot and leg to maintain balance,
and that both sides of the bottom of your feet press with equal pressure on the
bottom of your boot.
The position and orientation blades are mounted in
affects your balance and foot pains quite a bit.
As mentioned earlier, I prefer to modify
balance by changing the shape of the insole, so the blade can rest under the part of
the foot and body best designed to bear its
weight. Most boot fitters offset the blade mount to one side to achieve this.
If taken too far, offsets makes your foot very sore, and results in unequal loads
on the sides of your bone (creating possible bending and fracture) and can create
overuse injuries of your muscles and ligaments. Offsets can also twist the boot out
of the shape intended by the
boot maker. At least one prio boot maker, Klingbeil, voided warranties if the boot
had such
twisting. But offsets work quite well if they do not have to be offset more than a
very small fraction of an inch (a small
fraction of a cm).
Incorrect skating technique can also create
imbalance,
and generally will for beginners, who usually place all their weight on the inside
edge - ask your coach if this is the
problem. This is
because most beginners are afraid to put weight on the outside of their blades, for
fear of
falling over. Asymmetric or uneven blade edge sharpening can create the same effect,
so look at the edges carefully.
If the mounting plates are mounted to the boot sole
in such a way there is any space between it and the boot sole anywhere,
the plates and the blade will warp and twist, which makes it hard to skate. Some
blades and boots are "co-planar" which
means the parts of the sole where the plates mount, and the mounting plates
themselves are in one plane, making it easy to
move around to your preferences, but some (I think Klingbeils) are not. You can use
a belt sander to make a boot co-planar.
But some blades have the front and rear mounting plates in different planes, in
which case you would not want the
boot bottom to be co-planar.
Another technique to fill the spaces is to use "shims" - e.g., thin pieces of
leather or athletic tape - between the boot and blade so they
do match. If you need a thick shim, sand it into a wedge shape, so it will press
equally on different parts of the
area of contact.
The blades should also be vertically aligned when
you are balanced over one foot, so you don't
tend to skid. Shims,
or appropriate sanding of the bottom of the outsole, can fix this problem too.
Optimal Blade Placement
Most people's bones, muscles and ligaments are organized for weight support
to go through a line from about the middle of the heel, to the midpoint between the
big and second toes. That is the line along which blades should usually be mounted.
The mounting plates should usually be mounted to be centered forward and back in
relationship to the foot.
Generally speaking if that does not create balance,
it is because of unequal pressure on the two sides of the insole, or on the sides of
the boot -
discussed earlier. But the exact placement that makes your feet most comfortable and
least sore may vary.
Mounting blades
Do a "test mount" using the sliding hole slots in
the blade mounting plates to make sure you have it right. You have
to skate gently, avoiding jumps and only doing gentle step turns.
Once you have the mounting position right, you can
do a final mount by adding an extra screw to the front
and back section of the mounting - two if you do high jumps -
using the round holes. Leave the slotted hole screws in place to help hold the plate on.
Follow Bill Schneider's
recommendations on
screw types, sources and sizes. He buys screws from
McMaster-Carr in the US.
Bill says poorer quality screws often rust or break.
Bill and others say round head screws, whose heads have flat bottoms, grip the
slotted (test mount) holes better. Flat head screws, whose heads have conically
shaped bottoms, fit the round (permanent mount) holes in most blade
mounts better - but I suggest
you look at the mounting plate holes to be sure. (My note: round top head screws
don't always have flat bottoms to the heads,
nor do flat top screws always have conical bottoms to the heads - and it is the head bottom shape that matters.)
He buys #6 size, 18-8 thread stainless steel screws with "sheet metal" (i.e.,
self-tapping, not "machine screw") threads.
For slotted holes use round (or pan) head screws:
#6 x 1/2" (part #92470A148)in front, #6 x 3/4 inch" (part #92470A151) on
heel.
For round holes use flat head screws:
#6 x 1/2" (part #90065A148) in front, #6 x 3/4" (part #90065A151) on heel.
If you strip a screw hole, use #8 screws instead of #6. Larger, but they still fit
the mounting holes.
Self-tapping screws always work better and are less likely to split and damage the
material (in this case, the sole)
if you first drill a smaller diameter "pilot hole" and use it to guide the screw
when you screw it in the first time.
When screwing a self-tapping screw in or out, always press down on the screwdriver
with about 5 pounds or so of weight,
to avoid stripping the hole or the head of the screw - especially with soft
materials like leather, or with those
awful Phillips head screws.
Bill prefers Phillips head screws because they are easier to use with powered
screwdrivers. I
prefer [i]anything[/i] else, hex head screws best, because Phillips heads strip
(become too damaged
to remove with a screwdriver) very easily,
and then have to be removed with
screw remover/extractor tools
(there are ones that fit reversible power drills too - Alden GrabIt is a good
brand). Another approach is to use a tap and die set to create a new
reverse direction screw thread inside the original screw,
and then screw a reverse threaded screw in to force it out. Both these things have
the potential to damage your delicate
leather sole, so be careful. I think Phillips head screws are the universal symbol
of shoddy construction!
If after doing a "permanent" mount, you decide to
change the mount position, or you change blades, you
need to fill in the old holes for two reasons:
- Water gets into the hole, creating rot.
- If the hole positions overlap, you won't get a good strong connection if the
old hole is left open.
If the hole is only stripped and doesn't hold the
screw in well, you can avoid filling
in the hole by just using a slightly higher
diameter screw, as per Bill's recommendations.
Filling the hole can be done two ways.
- Fill the hole with an appropriate caulk, like Shoe Goo. This is
very simple. Wait 24-72 hours for Shoe Goo to
fully set before re-drilling in approximately the same place. If the holes don't
overlap,
that isn't an issue. Shoe Goo sticks to leather, rubber and plastic soles (e.g.,
PVC plastic). You can speed the set up a lot with heat from a hot air drier, but I
haven't played with this much.
- You can roll up a small sheet of leather to just over the diameter of the hole,
and pound it into the hole with a rubber
mallet. This is much faster, but don't hit your fingers.
Someone who is skilled with power drills could do
something much more elaborate, which lets you easily and quickly
change blades. Drill the holes all the way through, and use a nut inside the boot,
under the insole, to screw a bolt into.
Drill a shallow inset in the bottom of the boot, so the nut wouldn't push into the
foot. Show skaters sometimes do this
because they often skate on "artificial ice" (lubricated plastic), which wears down
edges quickly, so they may change blades every hour or two,
between sharpenings.
Obviously a fully drilled hole would be a lot harder to undo and relocate.
Interestingly, it is the mounting method many roller
skates use.
Be sure to periodically retighten your screws. If
they come loose, your holes will strip.
Ultima Matrix I Blade System With Removable Runners
Caution: An old style (Jackson) Ultima Matrix
mount system had relatively inexpensive removable blade runners - a
great idea implemented badly. (Don't confuse it with the newer Ultima Matrix
system which does not have removable runners.) It had very soft aluminum bolts and
nuts, and very small hex key heads. They keep coming loose, and need to be
tightened often, and the hex keys would wear a little larger and rounder every time
you tighten them or replace blade runners.
This is a problem partly because many people like me
who still have these mounts find
they need to remove the blades to sharpen them, because the old Matrix system gets
in the way of most sharpening machines.
It helps
to buy several hex key sets, whose hex keys invariably have almost infinitesimally
different sizes, and to buy both metric and ASE (English measure) sizes,
and to use the key that fits the current hole size as closely
as possible. That way they wear more slowly. It also helps to buy a spare set of
bolts, just in case the hole became too rounded to be
practical. The soft aluminum threads also strip easily, so put the nuts on
carefully.
The problem is so severe that I considered grinding
down stainless steel bolts and nuts to fit, but never got around to it.
In addition,
the blades would "click" and move around every time you touched the ice, because
there was a little space between the top of the runner and the surface
it should have touched, and Ultima hadn't taken thermal expansion and contraction
into account - many people found it helped to add in a little foam pad
in between. Unfortunately, Ultima dealt with the problems by stopping the manufacture of this otherwise very cost effective system, and stopped
selling the blade runners, leaving a lot of us in the lurch. Hockey boots have had
several different removable blade runner systems. Recently, at least two hockey companies
have provided very quick runner interchange systems that allow you to remove and
insert a blade by squeezing a trigger-like device.
Ultima's basic idea, with sideways mounted bolt and
nut that go on either side of the blade, was simpler and better,
if they had used the
right materials. It is a shame no one else has stepped in to make new runners
that fit the Ultima Matrix system, or to make stainless steel
or titanium bolts and nuts that fit, or to make a better engineered removable figure
skating blade system altogether.
Not only would such a system be more cost effective than replacing the blade and
mounting plates, but it makes it
easy to change blades for remote or delayed sharpening. People also often used to
put their skates in carry-on luggage, but placed two pair of
blade runners in different pieces checked luggage, to comply with some airport security people who are afraid blades are dangerous, while making it
likely that at least one pair would arrive without getting lost.
Blade Sharpening
It is very important that figure skate sharpening be
done by someone
who knows how to sharpen figure skating blades. Ask your coach and ask good skaters
around the local rinks
to find the best sharpener in the area.
Hockey blades are sharpened quite differently. A
single poorly done sharpening can ruin an expensive blade. For example, a hockey
sharpener may shave
off the toe pick, or round off the back of the blade. Speed skating blades are also
sharpened differently.
Poor sharpeners may also use a "hollow radius" - a measure
of the concave curvature across the smallest blade dimension, between the inside and
outside edges, that is
different from what you are
used to. If it is too large, your blade will act as though it is not very sharp, and
you will skid easily.
If it is too small, it may act sharper, and bite into the ice more than you are used
to, and the sharpening
will also wear down and need to be redone more often. Further, each time the hollow
radius is altered, the
sharpener wastes a lot of metal, and therefore greatly shortens the lifetime of the
blade. Each sharpening wheel
is shaped a little different, so going to multiple sharpeners will again waste a lot
of metal. A good consistent
sharpener only needs to remove 2 or 3 thousandths of an inch to keep the edge keen,
though they must remove
more if you wait long enough to let the bottom go flat. (Letting the bottom go
somewhat flat isn't bad in itself,
if you don't need and like sharp edges. It is a matter of taste.)
Poor sharpeners may also alter the "rocker radius" -
a measure
of the convex curvature along the long dimension of the blade. A good sharpener can
"fix" the rocker profile and
restore it to what it was, but doing so wastes a tremendous amount of metal.
(Blades with 8' rocker radius - less curvature - are supposed to go faster than 7'
rocker blades, though the fastest figure
skating blade I've used - the MK Dance - has 7' rocker radius. They are also
supposed to have better stability for jump landings. Blades with shorter rocker
radius -
more curvature - turn, spin and twizzle better.
Poor sharpeners may also fail to understand that
good figure skating blades are designed with more than one rocker radius. This is
partly to create a "sweet spot", approximately below the ball of your foot, where
spinning is easier because it has a curvature discontinuity
(like a top) or a region of reduced rocker radius. You will spin like a top if
the blade is shaped like a top, with a sudden convex change of
rocker where you want to spin, or with a lower radius rocker ("spin rocker") where
you want to spin.
The rocker change is also partly to create a region next to the toe pick which
is not skated on, in order to make the transition to the toe pick stronger. See, for
example,
these blade shapes, and these toe pick shapes.
Please recognize that blade shapes are
controversial, and not everyone agrees
on the best way to shape or sharpen a blade. It must work with your individual body.
If a bad sharpener creates
a uniform rocker radius, with no sweet spot - extremely common - it will be harder
to turn and spin. A very good sharpener
can restore the original shape, or give you a custom rocker profile.
If you sharpen your own blade, or even if you don't,
it is a good idea to photocopy
the blades (be careful not to scratch the glass) when they are as new as possible.
This lets you restore the original
rocker profile, if desired. It is very easy to accidentally alter the profile over
time by many sharpenings. Some
sharpeners insist on modifying the original profile before selling you the blade -
but I encourage you to photocopy
them first, in case the sharpener eliminates the sweet spot, or makes you unhappy.
If you like what they did, photocopy that.
A poor sharpener can also make one edge longer than
another - making
it hard to stay balanced - or make the edge heights non-uniform, making skating
quite difficult.
If you walk off-ice with your blades, even if it is
on the rubber mats often used
just outside the skating area, it can completely destroy the sharpness of the edge,
in a step or two, especially if you
use very sharp edges. Use blade
guards, which you remove as you step onto the ice. But, if you step onto the
ice while wearing
the guards, and don't realize it, you may fall, so be careful. An alternative
adequate for rubber mats, but not
for harder surfaces, is to walk on your toe picks, but that requires some balance. I
often use hard plastic
blade guards to walk on, but switch to breathable terrycloth guards afterwards to
prevent rust (see next page).
Quick and dirty instructions for sharpening figure skating blades, using hand tools:
If you can find out your ROH, you could start by
buying a Figure Pro-Filer kit.
It's not fast enough for major blade shape modifications, but it is a good tool,
for under $100, that imposes a constant ROH.
However, the gap widths on Pro-Filers vary. You may
need to file it if your blade won't fit, or add tape on each side of the gap if it
is loose. (In fact, thin tape is a good idea, so it doesn't scratch the blade.
If that is too expensive, I also like the old
Berghman skate sharpeners, which I think stopped being made around 1950 or 1960,
but are still available on
Ebay cheap. The cylindrical sharpening stones these tools use are a bit coarse and
crumbly, and they only come in 1/2 inch ROH. Be sure to tape the insides of the part
that grips the blade, so it doesn't scratch the blade either.
Wet the blade and the cylindrical diamond-dust
abrasive (coarse) stone in the sharpener with water, not oil, because oil sometimes
gets messy in your bag. Sharpen until you feel a very slight burr on each side of
the blade, reversing the orientation of the sharpener every few strokes. Then use a
wet flat stone (like you can buy at a dollar store) to hone (polish and push the
burr from horizontal to vertical) - that burr, which you can think of as a
flattened, stretched, knocked down tip of the edge, becomes the final tip of your
edge. (The edge on almost any steel cutting tool, such as knives, works the same
way.)
Total time is a few minutes / blade. Try to remove
as little metal as you can each sharpening. If you can measure that with a calipers
or micrometer (use very little pressure, so as not to damage the edge), .003 inches
or less is about right.
Sharpen roughly every 40 hours of use. Some people
sharpen more often, but do a very slight quick sharpening each time - if they love
very, very sharp blades.
I only use the coarse grain (diamond-dust) Pro-Filer
stone. The fine grain stone is nice after you have used the coarse stone if you want
extremely sharp edges.
The biggest things to pay attention to are:
- Don't damage your toe pick if you don't mean to, or you will be just like the
local sharpener you disliked. Be careful to make the sharpener stop before you get
there - maybe even put tape over the toe pick at first. Of course, once you have
removed enough metal, you may need to trim your rearmost toe pick so you still have
about the same roll from your sweet spot (see below) to touching your toe pick.
- Don't make an uneven edge, left-to-right. Use a balanced straightedge tool (like
a Popsicle stick) to verify that the two edges are level. Also, do an equal number
of strokes with the sharpening tool turned around helps keep things symmetric. An
uneven edge is a bit unpredictable, and makes it harder to skate well.
- Trace the original profile (the lengthwise shape). Try to maintain it.
- Don't loose your sweet spot. The sweet spot is the point, around the ball of
your foot, where the rocker (lengthwise) curvature changes. It represents a place on
the blade you can feel, where you can therefore balance. It will naturally wear to
be more uniform, but the abrupt change in curvature - you can substitute a very
slight (probably invisible) abrupt change in direction - is what you feel. People
like me who have trouble spinning sometimes need a spot we can feel.
OTOH, most sharpeners kill the sweet spot almost completely after a few sharpenings
- and a lot of skaters are still able to skate much better than me, so the need for
a strong sweet spot is a matter of opinion. Also, I like the sweet spot around the
ball of my foot, where I find it easiest to balance, but others might be happier
elsewhere.
- Don't scratch up the sides of your blades. Scratched up sides slow you down a
little. This is a little hard to do, because it scratches a little when you use the
flat stone. It helps to wet the sides of your blades too, maybe even oil them.
- I only actually sharpen every other time or so. The other times I just re-hone
the blade. I use a small piece of hard leather to push the edges outwards to be a
little bit more horizontal, than repeat the honing step. If it feels sharp - i.e.,
if you can still feel the edge - you don't need to sharpen. Honing instead of
sharpening every other time roughly doubles the lifetime of the blade.
- If your blade varies in width near the bottom, e.g., if it is tapered (thinner
at the ends than in the middle) or parabolic (thinner in the middle), sharpening is
a lot harder, and may not be worth it. If you mess it up, you can get a wavy shape,
with variations in the effective thickness of your blade, that could make skating
harder.
If the blade is thicker at the bottom, each time you sharpen, the blade will get
thinner. All you can really do is to measure the width at various points along the
length of the blade, and keep the relative widths (the differences between widths at
various points) the same.
- If your blade varies in width near the bottom, e.g., if it is tapered (thinner
at the ends than in the middle) or parabolic (thinner in the middle), sharpening is
a lot harder, and may not be worth it. If you mess it up, you can get a wavy shape,
with variations in the effective thickness of your blade, that could make skating
harder.
Each time you sharpen, the blade will get thinner. All you can really do is to
measure the width at various points along the length of the blade, and keep the
relative widths (the differences between widths at various points) the same.
- Rotate the cylindrical stone every few sharpenings, so it doesn't get flat in
one place.
Rocker Curve Templates
I have often argued that the most common rocker
radii measuring tool has measurement errors, because it only looks at 3 very small
points, and because it doesn't measure down the blade center or along the edges, but
is offset in such a way as to be sensitive to nicks and scratches along the sides.
(E.g., it may not measure the same radii along both sides.)
I believe you can get a better measurement by visual
comparison.
If you want to measure your blade rocker, download
and print this image of rocker curve templates:
If that doesn't show on your browser, look here
If your printer scales it right, the horizontal grid
lines will be .25" apart, and the curves will be .35" apart on the x-axis.
Otherwise, enlarge or shrink the printed page by the appropriate factor to make it
so. Cut the templates out, leaving a little white space around the boundaries, then
place one behind your blades, so that you can just barely see how the blades compare
to the black lines on the paper. There is not much visible difference between 7',
7.5' and 8' rockers - which is why some of us aren't sure it matters much. On the
other hand, spin rocker radii (the part forwards of the sweet spot) curves are a lot
different, and many of us think that matters a lot.
References
MK/Wilson Blade Mounting Instructions
Mounting
Blades to New Boots by Bill Schneider - well worth a look, especially if you
want to do your own
initial mount.
Common Skating Injuries And What To Do About Them
says mount position should vary for people with foot abnormalities such as
pronation or supination.
SkatingForums.com thread on Blade Sharpening Information/FAQ
Skaters Landing TV (Episode 3 is on blades.)