Sports Science Friday: Livin' on the edge

The weather service claims that Ann Arbor is due for 7-12 inches of snow today. We shall see how much truly falls--but I'm sticking with the winter sports ice theme no matter! While the chemical proclivities of ice are somewhat fascinating, what one can DO on the ice is pretty cool. There's olympic curling, figure skating, ice dancing, hockey, speed skating, and the IM sport favorite: broom ball. Ok, now all of you out there 'fess up: you know that you have definitely watched curling on a boring Sunday afternoon AND you definitely know who Dick Button is. Admit it. It's ok. You will not forfeit your 'man card'. Promise. And I promise not to subject you to the science of triple salchows, or images of Brian Boitano in spandex. Really.
Oh no, dear reader. Today's Sports Science Friday is allllll about the blade! en garde!

Skate sharpening is a pure science unto itself and equipment managers the world over know exactly how their guys want their skates hollowed. What? A hollow skate? Dumb girl...skates are made of steel they ain't hollow. HAH! Wrongo.
If you look at the bottom of a skate you will see that it actually is comprised of two thin blade edges separated ever so slightly in the center. The distance between the edges is called the radius of the hollow (ROH), the deeper the hollow the sharper the 'edge'. Goalies like flat hollows as they need to move from side to side and don't want an edge to catch. Super skater-finessers want a deeper hollow so they can 'dig in' to the ice and push off for quick starts and stops. It's about balancing glide and slide vs. grip and go.

The radius of the hollow is measured in 8th's of an inch. The term comes from the idea of the curve or hollow as the arc of a circle. (oh crap...now I gotta dig out the geometry). Actually MikeD at HFBoards is gonna break out the geometry--I'm just gonna recap. Remember that the radius of a circle is actually 1/2 the diameter of that circle. r = D/2. The depth of the hollow is 'simply' the arc of the radius of an imaginary circle ground into the bottom of the skate. The smaller the radius, the deeper the hollow. So a 5/8" ROH is deeper than a 1" hollow. The trick is making sure that the edges are even. If the hollow is off-set than one side will be 'deeper' than the other, producing 'stick' when one tries to skate. According to sharpeningsolutions: "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 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."

So all this blade stuff is REALLY important. Because if you are an NHL Ice Girl......ya gotta look gooooooood. I think you guys will like Yanina from the Chicago Blackhawks. Or this girl from New York: