Ice skating blade descriptions often feature a specification called When blades are manufactured (or sharpened), part of the decision to be made is what ROH to cut into the blade. Typical values for ROH might be between \u00bc” and 1\u00bd”, but more commonly for figure skates you’ll see values from 5\/8″ to 7\/16″. But what does this all mean?<\/p>\n Somebody who has never looked closely at an ice skating blade might have assumed that the blade surface (the part that is skated on) is flat, so looking at the blade end-on (rather than side-on), one might assume it looks like this:<\/p>\n <\/a><\/p>\n In an ideal world, a perfect skater could (would?) use flat blades. The disadvantages of the flat blade though are that unless the skater were always 100% perfect in their movements, they would likely fall regularly, especially after jumps. Using a non-flat blade surface helps us get better grip and control on the ice, and since we are all terribly imperfect, that’s the norm.<\/p>\n With that in mind, the blade is ground (sharpened) using a curve, creating a kind of arch shape over the ice. This means that the blade actually touches the ice on two rather sharp edges:<\/p>\n <\/a><\/p>\n The arch creates an empty space between the blade and the ice, and this is what is being referred to as the To create the hollow, take a circle with the desired radius, center it horizontally on the blade, then move it until the bottom corners of the blade just touch the circle at those two points. The arc between those points is the curve we want to cut into the blade:<\/p>\n <\/a><\/p>\n A larger radius means a larger circle, so the hollow that is cut out will be shallower. Conversely a smaller radius means a smaller circle, which leads to a deeper hollow.<\/p>\n Radius of Hollow (ROH) therefore refers to how deep a hollow is cut into the blade surface, and the value given represents the radius of the imaginary circle from which the hollow’s arc (curve) is taken.<\/p>\n The images above show an exaggerated representation of the ROH on the blades in order that it’s more obvious what’s going on. Drawn at scale, here is a 3\/16″ width blade (fairly typical) with four different ROH:<\/p>\n <\/a><\/p>\n It’s a bit hard to see the difference, so here’s a close up of the same four ROH profiles:<\/p>\n <\/a><\/p>\n The difference is hopefully visible now, but looking at a skate blade I suspect I would be hard pressed to identify which\u00a0ROH had been used!<\/p>\n The two sharp parts of the blade touching the ice are the One reason to use a reputable skate technician to sharpen your skates is to ensure that they are capable of aligning the cutting tools very precisely. If the tool is off-center even by a small amount, the results can be anywhere from irritating to disastrous:<\/p>\nRadius Of Hollow<\/q> (ROH). Ever wondered what it is?<\/p>\n
Radius Of Hollow<\/h1>\n
hollow<\/q> in
Radius of Hollow<\/q>. As for the radius part, you probably know that a radius is the length from the center of a circle to the outside (i.e. it’s half the diameter, or distance from side to side).<\/p>\n
ROH Drawn To Scale<\/h2>\n
Edges<\/h1>\n
edges<\/q>. I’m going to state what’s probably obvious here and confirm that the sharp part on the outside of each foot is known as the outer edge and the one on the inside of each foot is the inner edge.<\/p>\n
Misalignment<\/h1>\n