FLAT BOTTOM V Technology &
Blackstone Skate Sharpening Machines
The Flat Bottom ‘V’ (FBV) patent pending, is an evolution of the traditional method of sharpening skates. The FBV has recently been introduced by Black Stone Sports to coincide with their innovative ‘Spinner’ patent pending dressing system.
The Flat Bottom ‘V’ (FBV) patent pending, available only with the Blackstone ‘Spinner System’, offers the skater the ability to have both speed and agility. A blade sharpened with the FBV has the flatness of a shallow hollow and the edges of a deep hollow (the depth of a 2 inch radius and the bite edges of a ½ inch radius).
When using a traditional hollow, a skater would usually ask for a 1/2 or a 5/8 (referring to the radius of a circle). Asking for an FBV is a little bit different. When asking for an FBV, a skater will ask for a 90/75 or a 100/75, etc.
The first number is the width of the flat part of the blade, in thousandths, after the sharpening. This number is represented in the figure above as ‘d’. A thousandth is a way of measuring small lengths. One-eighth, 1/8, of an inch, for example, would be 125 thousandths. So, for example, the width of a 90/75 FVB (90 thousandths = 0.090 inches) is less than 1/8 of an inch (0.125 inches). Although the thickness of a blade varies from skate to skate, the typical blade is approximately 115 thousandths (give or take a few thousandths). This should give you an idea of the ratio between the blade and the flat area that an FBV puts on the blade.
The second number is the height between the edges of the blade and the flat area of the blade (in 10 millionths). This number is represented in the figure above as ‘h’. In the example given with the two FBV hollows, 90/75 and 100/75, a different angle of edge is obtained by changing the first number and keeping the second consistent, thus producing a different feel and more or less edge when skating.
When trying the FBV, a skater should understand that the feel on the first use will be different, but then after a few minutes of warm-up, the transition will be effortless and the advantages and speed of the FBV will be apparent quickly. The FBV is quite different from the circular hollow. We have found that the 90/75 is a good starting point and from there the skater can determine if the edge should be more or less sharp. Trust your pro shop for help and advice in deciding what FBV is right for you. When in doubt, try several until you find the perfect FBV.
The edges of the FBV are keener, so the same edge may feel sharper than the one you are used to. This allows you to skate on less of an edge and maintain the same bite. If you have tried the 90/75 and feel that you do not have enough edge, you should then try the 100/75. From our initial testing, we have determined that the 90/75 can be related to the edge of a 5/8 circular hollow and the 100/75 can be related to the edge of a 1/2 - 3/8 circular hollow.
The FBV provides the best of both worlds when it comes to speed and agility. With the flatness of close to a 2” radius, you will notice more speed and less drag. If you are used to slowing down when you stop pushing, you will notice your glide is a lot longer. With the FBV, you will notice a decrease in the number of strides necessary to get from end to end. Along with the increased glide and speed, you will notice that you still have a solid, keen edge to allow you to be as agile as you were before, if not more so. The result of this combination is more speed, solid edges to bite during turns and stronger legs right up until the final buzzer. With the FBV, you are able to increase your effectiveness on the ice with less effort.
History of Skate Sharpening
Skate sharpening is a process which, we suspect, started in the 1800s with a manually powered grinding wheel similar to that depicted in this picture from 1877. You can see the beginning of a radius being ground into the blade by the arc of the grinding wheel.
As time went on, the sharpening process fell into the domain of shoemakers, blacksmiths and knife sharpeners who began to use motorized vertical grinding wheels to sharpen skate blades. Discoveries about the process were made over time…one of which was that the smaller the vertical grinding wheel’s diameter (producing a larger ROH – radius of hollow), the sharper the edges of the blade became. This led to the realization that a deeper hollow (smaller radius) gave the skater greater mobility (bite) and that a shallower hollow (larger radius) increased speed (glide).
After years of using a vertical wheel it was discovered that a radius could be scribed in the face of the grinding wheel by placing the wheel horizontally and then rotating a single point diamond dresser across the front of the wheel. This innovation not only provided many variations of the radius, but also a consistent radius on the face of the wheel that could be produced and reproduced easily by any operator.
The latest innovation in the process of sharpening skates is the ‘Spinner System’ patent pending. This system uses the horizontal grinding wheel, but dresses the wheel with a ‘spinner’ instead of a single point diamond. A spinner is a disc with a radius machined on its exterior and which is then coated with diamonds. The diamond coated dressing wheel spins and, as it bumps against the face of the grinding wheel, dresses the grinding wheel with a precise radius. The spinner dressing system produces a more accurate dressing result with less effort than was previously required with a single point diamond.
The innovation of the Blackstone ‘Spinner System’ patent pending is that the operator has the opportunity to put any radius and, most notably, any ‘shape’ on the blade.
Traditionally, skates have been sharpened with a circular (arc) form on the bottom of the blade. This arc (hollow) is a piece of the circumference of a circle and can vary in depth. As the depth of the hollow changes, so does the bite of the blade’s edge. As the hollow gets deeper (with a smaller circle more of its circumference is on the blade), the edges become sharper and more pronounced. Typically this results in the skater being able to cut sharper and be more agile, but speed requires more effort. As the hollow gets shallower (with a larger circle less of its circumference is on the blade), the edges become less pronounced and the blade appears flatter. Typically this results in the skater being able to skate faster, but cutting takes more effort. (The sharper the edge, the more the blade will sink in the ice. Less edge creates more glide due to the fact that more of the blade is on the surface of the ice). Picture the difference between a quarter and a dime - the dime would produce a much deeper hollow because the blade covers more of its circumference compared to the quarter, which would produce a shallower hollow.
It is important to know what hollow you are skating on because it affects your skating technique and how your blade reacts with the ice. Also, knowing your radius/hollow will allow you to get the same sharpening you normally receive even if you travel to a different pro shop.
for technical data