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.
To begin , let's look at what different radii look like on the bottom of your blade. Note: These drawings are exaggerated for effect.
A SMALL RADIUS CREATES
"Deep Hollow"
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A LARGE RADIUS CREATES
"Shallow Hollow"
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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: "Is there enough edge?" "Is there too much edge ?"
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 skater’s weight, the skater’s discipline, the ice temperature, and the skater’s 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.
WEIGHT
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 and advanced level can skate on smaller radii , often finding it better for fast edging and footwork and better grip when landing higher rotation jumps; particularly effective for ice dancers. Skating on too small of a radius, sometimes 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 | ||||
COMPETITIVE/ICE DANCE | INSTRUCTIONAL/BASIC HOCKEY | BEGINNER | RECREATIONAL | HOCKEY GOALIE |
3/8"-7/16” | 1/2" | 5/8" | 3/4" | 1 TO 1 1/4" |
- A US Dime is ~11/16" in diameter or has an ~11/32" radius. This is ~1/32" less than a 3/8" radius.
- A US Penny is ~3/4" in diameter or has a ~3/8" radius
- A US Nickel is ~13/16" in diameter or has a ~13/32" radius. This is ~1/32" greater than a 3/8" radius.
- A US Quarter is ~15/16" in diameter or has a ~15/32" radius. This is ~1/32" less than a 1/2" radius.
SKATERS
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: Most beginner and instructional skaters 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 common is 7/16” to 3/8” for ice dancers and in between for synchro
ICE TEMPERATURE
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 depending on weight distribution.
Skating: When skating aggressively, or with uneven weight distribution over the blade, typically caused by pronation, 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: Ifthe 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. Qualified skate technicians will always use a small T-square or micrometer to measure the blade edges across the entire edge surface to make sure that they are exactly even. Years ago, sharpeners would be seen balancing a penny across the edges, which was close, but not exactly accurate.
#2 Skate blades are not all the same thickness. 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.
For more information about figure skating equipment, read our other guides or get in touch with us. We're always happy to help!
The article delves into the intricacies of skate blade radius and its impact on performance, discussing various radius sizes, their effects on edge sharpness, maneuverability, grip, and speed. Let's break down the concepts covered:
1. Radius Basics:
- Radius Definition: The radius refers to the curvature ground into a skate blade to sharpen the edges.
- Relation to Circle Diameter: The radius is half of the circle's diameter. For instance, a 1" diameter circle has a 1/2" radius.
2. Impact of Radius Sizes:
- Small Radius (Deep Hollow): Creates sharper edges, more grip, increased surface area contact with the ice, but also more drag and less maneuverability.
- Large Radius (Shallow Hollow): Results in less sharpness, decreased grip, less surface contact with the ice, reduced drag, and increased maneuverability.
3. Factors Influencing Radius Selection:
- Weight: Light skaters can handle smaller radii for deeper hollows, while heavy skaters might struggle with too much edge and excessive friction.
- Skill Level and Discipline: Beginners might benefit from larger radii for easier learning, while advanced skaters often prefer smaller radii for precise movements.
- Ice Temperature: Colder, harder ice might benefit from slightly smaller radii for improved grip.
4. Recommended Radii:
- General Radius Recommendations: Vary based on skating discipline and skill level, ranging from 3/8" to 1-1/4" for different skating purposes (e.g., competitive, recreational, hockey, figure skating).
5. Skater Preferences:
- Hockey Skaters: Forwards may prefer smaller radii compared to defensem*n of the same weight. Goalies usually opt for larger radii.
- Figure Skaters: Varies based on program level, often consulting coaches or instructors for advice on suitable radii.
6. Blade Maintenance and Uneven Edges:
- Causes of Uneven Edges: Weight distribution, aggressive skating, and improper sharpening can lead to unevenly worn edges.
- Sharpening Techniques: Ensuring even sharpening across the blade is crucial, using tools like micrometers to measure and maintain uniformity.
7. Considerations for Edge Maintenance:
- Skating Technique Impact: Uneven weight distribution during skating affects edge wear, necessitating proper maintenance.
- Proper Sharpening Procedures: The importance of grinding the blade's center and verifying skate holder adjustments to prevent uneven edges.
8. Final Recommendations:
- Advice for Skaters: Recommendations for different skater types, disciplines, and ice conditions, highlighting the importance of consulting experts for optimal radius selection.
This comprehensive guide covers the nuances of skate blade radius, catering to various skating disciplines, skater preferences, and maintenance techniques essential for ensuring peak performance on the ice.
