LEARNING ABOUT SKATE SHARPENING
Even and Uneven Edges
This article is intended to
help you understand the principals and theory of skate sharpening and to
help you accurately and consistently communicate, to the person
sharpening them, how you want your skates sharpened. E.G.: "I
want a 15/32" (just under 1/2") radius grind".
It is not our role to dictate or prejudice your view on skate sharpening. With that in mind....
It's been called a groove, a hollow grind, or a ground radius.
You could refer to it as: "I want a 5/8" radius" or "I want a 1/2" radius"
By grinding a radius into your skate blade you are making your edges sharp and depending upon the radius you choose, you are also making your edges more (or less) pronounced.
From grade school math, you may recall that a 1" diameter circle will have a 1/2" radius.
A 4" circle will have a 2" radius, a 3/4" diameter circle will have a 3/8" radius, etc, etc.
The diamond dresser attachment on most skate sharpening machines will dress (shape) the grinding face of the grinding wheel to the curvature shape of any radii between 1/4" and 1-1/4".
This is the radius that will be transferred to the skate blade by grinding.
WHAT RADIUS IS BEST ~ THE MEANING OF "SHARP"
Choosing a radius can be as simple or as complex as you want to make it. The following discussion will allow you to understand skate sharpening. You should also be able to then form opinions on your own.
A SMALL RADIUS CREATES
A LARGE RADIUS CREATES
After a skate has been ground it will have sharp edges regardless of how big or small the radius is. Keep in mind that the long speed skating blades used in the Olympics are honed flat with no radius. They are looking for maximum glide. While they are careful in the turns, don't ever doubt that these blade edges are not sharp!
The real questions are:
If immediately upon use a skater claims the skate is not sharp enough, they are usually saying, "this skate does not have enough edge on it to suit my skating".
How much edge a skater can tolerate is affected by four main variables. These are the skaters weight, the skaters assignment, the ice temperature, and the skaters skill level.
Warning: in no case should a radius smaller than 1/4" be attempted. Besides being too sharp for anyone, this will weaken the sharpeners grinding wheel and will create a safety hazard.
An extremely light skater can tolerate very small radii (producing a deep hollow and lots of edge). They do not have much weight to bear on the ice.
Beginner level skaters can learn most skills (particularly the hockey stop) easier by grinding their skates with a very large radius. As they progress the radii is decreased back to a normal level.
A heavy skater trying to skate on a small radius (too much edge) will bite into the ice so hard that they will have trouble stopping without chatter or going over the top of their skates. They will also loose glide to excess friction and be working harder. On the other hand, they will be able to hold a very tight turn!
Professionals can skate on smaller radii as they have the combination of leg/ankle strength and talent to get away with it.
Skating on too small of a radius feels like skating on soft ice.
While 3/8" radius edges are more pronounced than 5/8" they are also more fragile and less durable.
|A "general purpose" chart for radius by weight is as follows:|
|VERY LIGHT||AVERAGE||HEAVY||HOCKEY GOALIE|
|3/8"||1/2"||5/8"||3/4"||1 TO 1 1/4"|
Hockey: 1/2" seems to be the most common radius for kids through high school. Forwards generally prefer smaller radius than defense men of the same weight. Goalies generally prefer very large radius so that they can "kick out" without catching an edge.
Figure: kids (under 60 lbs.) can skate on a 1/2" radius. A 5/8" radius will take care of most recreational skaters.
When figure skaters get to the level where they are in a serious program, they will be under the guidance of a coach or instructor. The skater should consult these people for advice on the best radius for the program they are performing.
Most rink managers shoot for an ice temperature of approximately 25 degrees Fahrenheit. A temperature of 17 to 23 degrees is considered "hard hockey ice", 25 to 26 degrees is considered good figure skate ice. Slightly smaller radius may be used on colder/ harder ice and vice versa.
What causes Even and Uneven Edges
Skates needing to be sharpened do not just have dull edges; they will also have unevenly worn edges.
Skating: When skating aggressively, particularly in hockey, the inside edge is worn off more than the outside. Furthermore, the inside edge is worn mostly under the ball of the foot and not much at all near the tail of the skate blade. If you don’t believe this, go inline skating for a week and don’t rotate your wheels!
Improper sharpening: If the blade is not ground down along on the absolute middle of the skate blade it will always have uneven edges. There are two ways this can happen.
#1 The outside edge, which is higher, is therefore “sticking out” further than the inside edge and must contact the grinding wheel first. The high material will then be taken off and the grind will drop into the center producing even edges It's the center of the Blade that must be the guide, not the center of the worn radius. If this rule isn't followed, you get uneven edges.
#2 Skate blades are not all the same thickness. “Standard” (if there is any such thing) hockey blades are .110" thick but differences in thickness occur between different brands and even within a brand. So the skate holder adjustments must be verified with every sharpening and not left at some arbitrary "standard" setting. If this rule isn't followed, you get uneven edges.
The oldest way to check for even edges is to place a coin flat onto the bottom of your blade. If your edges are even, the coin will form a 90 degree angle to the side of the skate blade. There are two problems with this method. The coin tends to easily fall off the blade and the coin does not extend far enough out either side to magnify any error.
In the second drawing, we are using a 6" flat object. We now have 3" of material sticking out both sides to magnify any error and make it more easily recognized.
a clever measuring tool in use
is a 6" long flat piece of aluminum angle with a magnet glued to
the middle. This will hold the device in place even on stainless steel
skate blades. Or, in a pinch use a plastic credit card (or drivers
license) and hold it in place with your finger tip. You don't need to be
a rocket scientist to check for even edges!!!
Most skates can get along without cross grinding. However, if the skates are in poor condition, a cross grinding may be necessary. Blades that have been beat up by walking on concrete, are badly rusted, or have a sizable nick/gouge, would all be candidates for cross grinding.
Cross grinding (roughing) prior to sharpening can get the blade quickly below the problem area and create a nice starting finish. Keep in mind that cross grinding skates that don't need it wastes blade material.
Last updated 03/11/2004