About the Art of Skate Sharpening
by George Crha
It was in England in 1870 that the hollow (then “gutter”) was first ground into the skating blade. Since this time, the machinery has improved significantly, but the skill of the operator to achieve technically perfect grind, especially for figure skaters, is sometime questionable.
Since the compulsory figures are history, the only grind that left is the free skating grind, but technically speaking we have more than one free skating grind. The depth of the hollow has to be determined by the skater’s mass and skill level. A skate sharpener with inadequate knowledge can do serious and unrecognized damage to the skater’s technical development.
Now for another example of the not-so-obvious consequence, consider the Axel jump (single, double, triple): For the top world-class male skater, the triple Axel jump marks the threshold of true champion quality. The correct take-off of the Axel is not a clean edge (as it was in the 1930’s). In the moment of quick application of forces, the skater makes a sickle-shaped slide-skid behind the center point of the blade rocker. The balance is quickly transferred to the ball of the rocker and master toe pick.* When the edge of the blade is too sharp (because of the depth of the hollow) the skater is not capable of making the necessary skid. Clean edge take-off with any broadening is working against the very principles of the laws of biomechanics. The strong pressure on the outside take-off edge provides the necessary powerful lift, which is evident in the height of this jump.
Hollow depth - bite angle to the ice
Diagram # 1:
The depth of the hollow is creating the bite angle of the edge to the ice. The flat hollow is better for the flow.
The grind is usually 5/8 inch to ½ inch plus or minus 0.
Criteria of Hollow Selection:
- Mass of the skater
- Technical level of skater
- Width and shape of the blade (shape →straight or tapered)
- Personal preference
The Blade Rocker Maintenance:
The proper curvature of the blade, which is called “rocker,” is the composite of three tune-in curves which cannot be altered (except destructively as a result of sharpening). Keeping the curves in the original state is only possible by a cross-grind technique of skate sharpening, yet almost all sharpeners use a horizontal grind technique. The horizontal wheel easily damages the ball of the rocker in the most important part (under the master toe-pick) (see diagram 2) for spinning and especially for jump take-offs.
We see how skate sharpening affects the mechanics of skating. As in any successful business/trade, attention to detail is required, but sometimes missing.
Born and raised in the Czech Republic, the son of a hockey player in the Czech elite league, Crha started skating at age 3 and was a hockey player until he switched to figure skating when he was 12. In 1957, after seven years competing as an amateur, he began a 10-year stint as a professional skater, working as many as 700 shows per year. He was part of the Vienna Ice Revue, performing all over Europe. Crha came to Canada in 1967, a year before the Soviet takeover of Czechoslovakia, first settling in Montreal before a move to New Brunswick. He also coached with the Minto Skating Club, the Victoria Racquet Club, and was hired by clubs in Kuwait and Milan, Italy. “It was an important decision to immigrate and you need some guts to do it,” he said.