Standardization of equipment terms within ice skating :)

[Query]

There isn't any real standardization of terms within the skate community, in part because there hasn't for the most part existed any big standard places for skate techs to go to school in being a skate tech, or any books on the subject. What literature exists disagrees on terminology and techniques. I get my term definitions from various techs, as well as the web sites belong to equipment manufacturers. But they don't all agree.

And the hockey community seems to use different definitions of terms from the figure community too (e.g., a hockey sweet spot might be the point near the center with minimum curvature and/or horizontal alignment).

Even basic terms like "Rocker" have different definitions. E.g., the cusp(s) between the main rocker curvature and spin rocker curvature that I have learned to call the "sweet spot(s)" is what some people call the "Rocker(s)", which is quite different from the longwise radius of curvature I have learned to call "Rocker" or "Rocker curvature".

Again, some people use "dovetail" cut or grind (fatter at the bottom) for what I and some other people call "side honing" (i.e., fatter grind at the bottom) - but "side honing" is used by others to refer to any design feature that makes the sides of the blade non-flat or non-parallel - such as tapered (which I think usually mean in front, but is sometimes used to mean fatter in back), or parabolic grinds. I think "hollow" has a pretty uniform definition within the figure and hockey communities, but a hollow ground knife is one with inwardly curved side-honing.

I think MK and Wilson could have standardized terms, at least within the figure skating community, but, as you have observed, they haven't been all that open in explaining blade design features and parameters. In effect, the terms become cool-sounding buzzwords without uniform meanings. E.g., I have never understood how a blade can be simultaneously "parabolic" (thinner in the long-wise middle) and "tapered" (see above), but they have advertised some skate blades that way.

So - standardization of blade design terms isn't part of this sport. You have to guess what definition each person is using.

It's not unique to ice skating. I sometimes find it amusing to go through a committee-written science textbook, and note the inconsistent formulae and the inconsistent technical definitions implied by them.

Can you folks come up with other examples and definitions?

[MCsAngel2]

Footbed vs. insole. One refers to the removable piece your foot rests on, the other refers to the inside bottom of the boot. The problem is, which term goes with which definition is not standardized and I have seen each term used in both ways! Gets confusing sometimes.

[tstop4me]

Getting all concerned to agree on definitions is only half the battle.  Getting all concerned to use them is the other half.  I worked for ~15 yrs as a telcom systems engineer.  A big chunk of my responsibilities was writing requirements for the design, test, and field engineers.  Wherever an industry standard term existed, I used it.  But often the other engineers stuck to their own lingo.  E.g., in cellular telephony, standards documents use the terms "forward channel" and "reverse channel"; but design, test, and field engineers would always use "downlink" and "uplink".

In the US, standards for thermal fusion of metallic joints fall under the auspices of the American Welding Society (AWS).  There is an AWS standard defining "solder" vs. "braze" vs. "weld"; this standard has been accepted as an American National Standards Institute (ANSI) standard, so it's authoritative.  By this standard, the proper term is "silver braze"; "silver solder" is designated obsolete, and current use is not supported.  Yet, I frequently see "silver solder" in reference to joints in traditional design figure skate blades (blade body thermally fused to a sole mounting plate and a heel mounting plate).  Eclipse uses "silver welds" or "full silver welds" for their blades (beats me what the difference is), and that's just plain wrong.

[Query]

Oh dear. I saw "Silver solder" once - I think it was in MK and/or Wilson literature, and kept using it, because I assumed they were an authoritative source about their own blades, to the extent that they do describe them.

But the question is, do MK/Wilson still use it? I should check their current literature and ads.

Or maybe trademarks and patents... Maybe they are designating a slightly unique or proprietary process.

Or maybe Britain (where MK/Wilson are located) follows a different standard?

How about the units for blade length, rocker and hollow radii: In countries where the metric system is the legally preferred standard for many things, such as Europe, are those measures still usually in inches?

I have noticed that hollow size in what I have read for skating are measured in radii, as are the size of the Pro-Filer sharpening stones - but if you buy abrasive cylinders (called by many other names, like "round stones") from other sources, they are usually sized by diameter (E.g., a diameter of 1 inch is a radii of 1/2 inch)  - an important distinction, if you buy your abrasive cylinders from someone other than Edge Specialties.

[tstop4me]

I have noticed that hollow size in what I have read for skating are measured in radii, as are the size of the Pro-Filer sharpening stones - but if you buy abrasive cylinders (called by many other names, like "round stones") from other sources, they are usually sized by diameter (E.g., a diameter of 1 inch is a radii of 1/2 inch)  - an important distinction, if you buy your abrasive cylinders from someone other than Edge Specialties.

This is not really an issue, as long as the size of the cylinder is specifically listed as "radius" or "diameter".  For mechanical parts, "diameter" is commonly used in instances in which the cross-section is a full circle; e.g., diameter of a circular hole, cylindrical rod, or drill bit.  Tools such as micrometers, calipers, hole gauges, and bore gauges can readily measure the diameter.

"Radius" (as in radius of curvature) is commonly used in instances in which the cross-section is an arc (part of a circle).  E.g., machinists use radius gauges to measure the radius of a rounded corner.  For skate blades then, "radius of hollow" and "rocker radius" follow this convention.  Since Edge Specialties stones are specialized for skate sharpening (rather than general purpose abrasive grinding and polishing), it makes sense for them to designate their stones according to the radius of hollow produced. 

[Query]

I can't find "silver" in a soldering or brazing context on MK's or Wilson's current websites, except .

BTW I notice that MK - and therefore probably Wilson too - now say their blades are "laser cut"
  https://www.mkblades.com/about-us

Skater's landing says

The solder used to attach the blades onto the soles of the boot may not hold up to the stress of repeated landing from jumps. Wilson and Eclipse products are all silver soldered. MK silver solder theirs, too, but the top quality blades such as Vision, Phantom, Gold Star etc. are hand brazed with bronze, to make the attachment stronger and more secure.

There is a lot more information at Skater's Landing on blades - too bad it isn't from the manufacturers themselves, which would be more authoritative. But note that they prefer "radius" to "rocker" or "rocker radius".

Tstop4me, you said you had a different definition of "sweet spot" than I do. What is it? Mine is the place(s) that the rocker radius changes - e.g., between the main rocker and the spin rocker.

[tstop4me]

Tstop4me, you said you had a different definition of "sweet spot" than I do. What is it? Mine is the place(s) that the rocker radius changes - e.g., between the main rocker and the spin rocker.

* As I previously posted, a proper response will require preparation of drawings, which I plan to do.

* In the meanwhile, I'll provide you with a summary of major points.  You'll probably have follow-up questions.  If you do, I'll address them later in my more detailed response, which will include the drawings.

* You have previously referred to the transition point between the spin rocker and the main rocker as a "cusp".  "Cusp" has certain mathematical definitions, which I do not intend to get into [even mathematicians don't agree on a single definition].  But I'll simply give one example of a cusp that readers here are familiar with:  that found in the trace of a three turn.  In a well-executed three turn, the pattern formed on the ice looks somewhat like the numeral three:  3 (not to scale; not exactly this shape).  The point at which the turn is executed (front-to-back or back-to-front) is a cusp.  One characteristic feature of a cusp is that it's a sharp point. 

In a skate blade, the only places in which we would want a cusp is at the tips of toe picks.  We want the working edges of the blade (the edges that contact the ice) to be smooth along their entire lengths; hence, we do not want cusps along the working edges.

* Your definition of a sweet spot leads to the following consequences:  (a) The position of the sweet spot depends only on changes in the curvature of the blade.  It does not depend on the position of the tip of the drag pick.  (b) As the blade is repeatedly sharpened, if the original profile of the blade is maintained, the position of the sweet spot along the blade remains constant.  (c) If the blade has multiple changes in curvature (such as the compound spin rocker of the Coronation Ace), the blade will have multiple sweet spots.

* From my reading of the figure skating literature, the "sweet spot" is defined in the context of a scratch spin.  There are geometrical complications arising from interaction of a blade with an actual ice surface;  I won't address those here.  Here is a simplified procedure that gives a close approximation of the sweet spot.  Place the skate upright with the bare blade in contact with a flat surface (such as a wooden or plastic cutting board).  Rock the skate forward until the tip of the drag pick just touches the flat surface.  Look at the blade from the side.  In the ideal case, the blade will touch the flat surface at one other point, the tangent point; this is the sweet spot on the blade [in an actual case, the blade will touch the flat surface along a region, rather than a point; but I won't address this complication here].

* In the context of a scratch spin, if you don't rock forward enough (drag pick not touching the ice), you will be spinning only on a single point further back along the blade.  If you rock forward too much (working edges lifted clear off the ice), you will also be spinning on a single point, the tip of the drag pick.  [Again,  I'm using "single point" for a simplified discussion.]  But if you rock forward just right (Goldilocks scenario), you will be spinning on two points, the tip of the drag pick and the sweet spot; consequently, the spin will be better controlled and more stable.

* As a consequence of this definition:  (a) The position of the sweet spot depends on both the profile of the blade and the position of the tip of the drag pick.  (b) As the blade is repeatedly sharpened, even if the original profile of the blade is maintained, the sweet spot moves backward (assuming you don't trim the drag pick), because the position of the tip of the drag pick relative to the edges changes as the edges are ground down.  (c) If the blade has multiple changes in curvature, there is still only a single sweet spot [here I'm talking about a normal figure skate blade profile, not something anomalous like a serpentine profile].

* Note that commercial blade maintenance gauges (such as Sid Broadbent's Wellness Gauge and the PBHE Blade Curvature Gauge cited previously) use the definition of a sweet spot I've given.   They therefore work independent of whether the spin rocker is round or flat, short or long.  There is no error in accidentally characterizing the main rocker in the case of a short spin rocker; the tangent point is the tangent point, irrespective of the portion of the blade you ad hoc classify it to be in.  [Although the various zones characterized as "Good", "Repair", and "Discard" are based on Wilson/MK spin rockers.]

[Query]

https://www.wolframalpha.com/examples/mathematics/calculus-and-analysis/applications-of-calculus/cusps-and-corners says

Cusps and corners are points on the curve defined by a continuous function that are singular points or where the derivative of the function does not exist. A cusp, or spinode, is a point where two branches of the curve meet and the tangents of each branch are equal. A corner is, more generally, any point where a continuous function's derivative is discontinuous. Use Wolfram|Alpha to locate and visualize cusps and corners.

This is consistent with my usage.

https://www.lexico.com/en/definition/cusp defines the first generic definition of cusp as

A point of transition between two states

However you can also find mathematical definitions more like yours, in which the tangents are NOT the same, e.g., at Merriam-Webster, or for that matter, the second definition at https://www.lexico.com/en/definition/cusp.

I have no idea why different people in mathematics define the term differently, but there are other examples of that sort of thing - e.g., some people define 1 to be prime, but most specifically exclude it from being called prime.

My understanding has been that the transition between the spin rocker and the main rocker should be fairly abrupt, though that isn't always true. However, AFAIK, you are right that none of the major figure skate blade makers make it a change of direction (i.e., make the tangent direction change), which is the second mentioned definition of a cusp on a curve. BTW I do create a very slight change of direction there, to emphasize the spot, and make it easier to feel - like the bottom of a top, but not visually obvious. I find it easiest to find that spot if I can just barely feel the transition. But I've never met a skate technician who told me they did that too - though many skate technicians sometimes re-emphasize what I call the sweet spot in other ways.

Most of the coaches I have had say, BTW, that on an optimally performed scratch spin, the toe pick does NOT quite touch. That leads to a faster spin. Thus, there is only one area of contact. However, many skaters initially let the drag pick just barely touch in order to feel the optimal spin point. However, one of my past coaches said that in school figures, she was once taught to create a "loop" on some types of 3-turn, in which there were two points of contact, moving in opposite directions. But I haven't found anyone else who confirmed that.

In any event, both the toe pick and the further back spin point on the blade do sink somewhat into the ice. According to  one expert skate tech I consulted, almost the entire bottom of the blade between those two points go into contact, and you can see this by marking it with a pencil - the pencil marks will rub off. Thus, the non-skating zone that Broadbent and others refer to may not be technically correct. BGW, remarkably enough, some very good jumpers actually make all the picks, not just the drag pick, touch, especially on toe jumps. (I'm not nearly flexible enough to do that.)

The usage of "sweet spot" that I use is consistent with what several fairly expert skate techs used in discussions with me. But this is just an example of how different people define things differently.

What would you like to call the transition point between the two rockers, assuming you do want it to be fairly abrupt.

[tstop4me]

What would you like to call the transition point between the two rockers, assuming you do want it to be fairly abrupt.

* I would simply call it the transition point between the two rockers, and leave it at that.  I would avoid specialized terms that could cause confusion unless they are necessary (e.g., specifically distinguishing different geometries).

* Note that the generic definition of "cusp" that you cited

"A point of transition between two different states."  (https://www.lexico.com/en/definition/cusp)

is used in a figurative, not technical, sense.  Specific examples in that link include:

    'those on the cusp of adulthood'

(click on "+ More example sentences")

    'He is also a black man coming-of-age on the cusp of two shockingly different decades, the 1950s and the 1960s.'
    'It is one of rapid change, on the cusp of something new, different, and exciting.'
    ''The economy is virtually firing on all cylinders again, and is on the cusp of a new era,' he says.'
    'Mind you, sometimes, now and again, Nature confounds us by letting an early break of fair skies extend itself a little, hover on the cusp of change and then, once the weather men are completely confused, settle in for a long hot summer.'

.....


* With respect to your citation from WolframAlpha (https://www.wolframalpha.com/examples/mathematics/calculus-and-analysis/applications-of-calculus/cusps-and-corners/), that link includes two specific examples of cusps:

https://www.wolframalpha.com/input/?i=cusps+of+sqrt+%7Cx-2%7C+-+cbrt+%7Cx%2B2%7C&lk=3

https://www.wolframalpha.com/input/?i=cusps+1%2Bx-%28x%5E2%281-sqrt%287%29x%5E2%29%5E2%29%5E%281%2F3%29&lk=3

Each example includes a plot with the cusps highlighted as red dots.  Note the distinctive sharp points.

[Query]

Whatever.

The way I see it, the lack of a standards body, or common educational materials, means that each good skate tech gains expertise largely on his or her own, and ends up making up his or her own terms.

I use the terms the way the people I know best used them, but that can therefore be completely different from what many others use. That makes things interesting, but also confusing.

So maybe you are right - the differing definitions of "sweet spot" mean that my usage of that term creates possible confusion.

But that is true of many things in skate equipment terminology. E.g. - "hollow" in most of the literature pertaining to non-skating blades refers to a form of side honing in which the top and bottom of the blade are thicker than intermediate height levels (BTW I'm not knowledgeable enough to why many such high end blades, even kitchen knives and razors, are slightly "hollow ground".), but I think it's usage in hockey and figure skating is pretty uniform in terms of referring to a recessed line or curve down the middle of the bottom. And I only recently realized that many people in the skating community use "rocker" to refer to long-wise curvature transition points - which I call sweet spots - not to the curvature itself. So should one also abandon "rocker" and "hollow"? You have to start somewhere.

Even pretty basic things like shoe sizes not only differ significantly country-to-country, but also brand-to-brand, and sometimes model-to-model within the same brand.

Even the medical community doesn't completely agree on technical terms - e.g. "pronation" and "supination" have one one meaning to podiatrists, and a somewhat different meaning to surgeons who work on feet. (I found found a warning to that effect in educational materials designed for physical trainers, who sometimes take instructions from both.) Again, "stress", "strain" and "lateral" have one set of meanings to the medical community, but quite different meanings to the physics community. (I presume the physics community and engineering communities use the same definitions of these terms as each other, but might be wrong even there.)

[tstop4me]

Whatever.

The way I see it, the lack of a standards body, or common educational materials, means that each good skate tech gains expertise largely on his or her own, and ends up making up his or her own terms.

I use the terms the way the people I know best used them, but that can therefore be completely different from what many others use. That makes things interesting, but also confusing.

The key take-away is the consequences of particular terminology, as I pointed out above. 

In some instances, there are no consequences.  If I'm a skater purchasing blades [rather than a producer making blades], am I going to choose among blades depending on whether the joints are advertised as soldered, brazed, or welded?  Probably not.

But if you ask a tech to produce cusps somewhere along the edges of your blades, don't be too shocked if your blades end up with  sharp-pointed pick-like structures pointing out from the edges or sharp-pointed notch-like structures pointing in from the edges.  If you complain, "What the __ did you do to my blades?", he can chirp back,  "You asked for cusps, I gave you cusps."

And if your coach asks you to stand by the boards and rock your blade back-and-forth to find your sweet spot, and you reply, "My blade has two sweet spots at which the curvature changes.  Do you want me to find the rear sweet spot or the front sweet spot?", don't be too shocked when she looks at you totally puzzled.  But since you're paying her $X/hr, you can debate it with her as long as you please.

[Query]

Excellent points. But I sharpen my own blades. And I'm not taking lessons from a coach at present. The only cost comes from making irreversible mistakes.

Some coaches would have an idea what I wanted - I know of a few who sharpen their students' blades. Also I knew a ice/roller/inline speed/hockey/figure coach who also ran a skate shop, where he sharpened figure, hockey and speed skates, as well as skis, fixed bicycles, and rebuilt skates. He gave me a lesson on how to sharpen using Pro-Filer, and played around a lot with equipment in general. He was a real artist. I really should check up on whether he is still around.

OTOH, the coach I liked best, as a coach, told me I was spending too much time learning about equipment, and was not herself not all that knowledgeable about such things. And that was the coach who was best at the physics-based descriptions of skating technique that I often need.

[tstop4me]

If you have no need to communicate with anyone else, standardization of terminology is unnecessary.