affuteur: quand vous affutez, quel roh vous faites pour quel patineur?

[marc]

Je voulais savoir quel roh vous pratiquez dans vos pays?

cela fait 3 ans que j'affute et je vais vous dire les roh que je pratique:

5.5/16 :pour les confirmés, poids normal, pour les sauts simple et double , pour la danse solo niveau national
6/16:   pour ceux qui ont un niveau moyen et qui commance à patiner avec un coté de la lame( carre)
6.5/16:  pour les débutants, adultes et les patineurs un peu costaud

Je me demande s'ils ne se sont pas habitué à cela ...
quand j'essaie de chercher, je trouve pas grand chose si ce n'est que le roh classique est 1/2 pouce.
Et je me demande si je ne fais pas trop creux....

un ancien patineur de notre club qui faisait les triples saut faisait encore plus creux que 5.5/16 alors que moi je trouve que c'est déjà tres creux!!

Alors je voulais avoir un peu vos avis...

Bien à vous tous dans vos différents pays et merci de m'eclairer un petit peu

[Query]

There is no single standard.

I believe studies have shown that the most common hockey ROH in NHL (The major professional league in Canada and Mexico) is 1/2". But the online advice has been that it should depend on the skater's weight and aggressiveness. E.g., a lighter skater, or one who isn't very aggressive skater needs sharper blades, which is taken to mean a lower ROH. The variation with weight and aggressiveness makes sense for figure skaters too.

And I think that most people I know stay with the ROH the blade comes from the factory with - at least on factory pre-sharpened blades. That usually means 7/16" for most figure skating blades, but 3/8" for MK Dance (because it is ground "thinline" - thinner at the bottom of the blade).

But Mike C told me that many people in New York City used 1/4". And for some reason a lot of the hand tool sharpeners available cheap from China are that.

And the few people I've known who did school figures - which is now similar to what is called "skating skills" in the U.S., want longer glides, so they sometimes choose 3/4" or even 1".

I'm not sure if it makes sense to use a different ROH on synthetic (lubricated plastic) ice. Edges wear out so fast that maybe people choose higher ROH??

The best skate techs I've known give the skater what they ask for. Or they try to copy what the skater already has.

Most skate techs remove the sharpening burr, by using a flat stone, slanted slightly inwards towards the centerline of the hollow. That makes the blade less sharp, and the amount of it you use might vary. Coarse grain wheels and stones also produce a less sharp edge than fine grain wheels and stones. And the rocker length affects effective sharpness too. So ROH isn't the only factor in sharpness.

Also, some blades are said to have a dovetail shape - meaning that the sides of the blade near the bottom slant inwards, which means that the angle included between the hollow surface and the sides is less. In theory, that would let you use a longer ROH to get the same angle.

The speed skaters and Nordic ice skaters I've talked to about this say they don't use hollow.

[R45]

RoH for hockey players:
A general rule used in Europe to find a suitable radius of hollow (in mm) for adult ice hockey players, is to divide the body weight (in kg) with π (3.14).
Example: if your weight would be 80kg = 80kg /3.14 = 25mm (1").
Hockey players in the US and Canada are generally skating on a smaller RoH than Europeans.
Though, there are by now enough examples in the NHL of players using a very high RoH. Paul Coffey, Mark Messier, Matt Cullen and Sergei Gonchar being some of the most famous ones.
25mm (1") and above may sound extreme, but these players are so good at skating that it is their preference to maximize their glide and speed at the expense of bite.

My advice is: go for the shallowest hollow you feel comfortable with.
The choice of RoH is always a compromise.
With hollows such as 13mm (½ ") the edges are always biting.
The more flatter the hollow becomes the more edge control you have to apply.
At RoH 19 (¾ ") it becomes scary for most of the skaters to change skidding into controlled sliding.
From 25 (1") onwards it's all about good edge control.
You have to try it out to know how much speed and less fatigue you can gain at the expense of bite.
Keep in mind it might take a few skating sessions to utilize the benefits of flatter hollows. 
Wally, Skater and Skate Sharpener

[AlbaNY]

Back in NY the hockey players I sharpened for basically always wanted 1/2".  I can't really remember anyone asking for another hollow. 

I'm still trying to figure out the number system in Germany.  They just ask hockey or figure skater and only have those two options.  I don't get sharpenings done here and haven't gotten a mini job yet so I can't say more.  I believe I used to get 17 in Romania? 

[Query]

I saw a video once (from Blademaster's) that said there were differences between hockey in the U.S. and Europe.

In particular, in the U.S., most hockey is played on NHL size rinks, whereas in Europe, they said it was more often played on larger Olympic size rinks.

Blademaster's video said that meant the central portion of the blade should have a flatter rocker - in fact that many players wanted no rocker curvature in the middle, presumably because the larger rink let people go faster, and they could stop and change directions faster.

I don't know if that would also affect ROH.

But if it does, then a difference in rink sizes could perhaps affect figure skating too.

Even in the U.S., many figure skaters prefer to practice on Olympic size rinks - but most skating facilities don't have them.

Obviously, if a skate tech has to change ROH more often, they wear down their grinding wheel and their dressing tool more rapidly, and they also have to spend time doing so - time they could be earning money by doing more sharpenings. Even if they use different wheels for different ROH, they have to spend time changing wheels. So some skate techs (or their pro shops) try to settle on one ROH. Or push everyone to be willing to use one ROH. Some charge more for other than their preferred ROH.

Also, some people feel the ROH should depend on the temperature of the ice. E.g., many rinks set up to be best for hockey keep their ice colder (and harder) than rinks more optimized for figure skating. I was told rinks optimized for curling takes warmer ice than either.

When I sometimes had to skate on outdoor ice, which sometimes creates a lot of very rough ice, and variation in surface conditions, I kept my blades extra sharp, so I could cut through to get a better surface.

Perhaps there are also variations for humidity? Because a lot of humidity produces rougher ice too.

So not everyone will agree on what ROH should be. So a skate tech who is willing to give skaters what they want might be able to charge more - but might have to spend more time and supplies doing that.

[Nate]

I started on 1/2" but moved to 7/16" a long time ago - and because I felt like I wasn't getting enough grip.

Most blades are designed with a 7/16" recommendation, so it also made it easy from that end, as well.

It's kind of the default ROH for a lot of techs (when the skater doesn't specify anything differently) when sharpening free skating blades.

[R45]

Radius of Hollow for figure skates

Skate sharpeners are supposed to advise the skaters and help them to find the best RoH for their kind of skating.
But this is hardly the case. This is what usually happens:
•    The skater does not have contact with the sharpener
•    The sharpener does not ask which RoH the skater wants and applies the "house cut" which is usually 13mm (½")
        With deeper cuts the edges are wearing out faster than with shallower cuts.
•    The sharpener is not a skater and cannot give tailored advice.

Fortunately, some sharpeners do have the knowledge and experience to advise the skater (figure, hockey, freestyle, recreational).
There are 4 main levels of skaters:
1.    Beginners
2.    Intermediate
3.    Advanced
4.    Expert
Advanced and expert skaters can skate on any cut and the choice of RoH becomes a personal preference influenced by body weight, personal style, age, level of edge control, ...
Beginners and intermediate skaters can use some help by means of a flatter hollow between 19mm (¾") and 25mm (1").
The principle of RoH for beginners is simple:
The deeper the hollow, the more the skates control the skater.
The shallower the hollow, the more the skater controls the skates.
People these days are generally skating on a too deep hollow (figures and hockeys alike). The better your edge control, the shallower the hollow can be.
Good edge control makes your body adaptive enough to do those turns without the need for a deep hollow. If you are good enough, you never need those deep cuts. You will be able to cut those corners with the extra advantage of more glide.

[Nate]

Good luck to all beginners skating on hard hockey ice during the winter up here with a 1" hollow.

The ice up here gets too hard in the Winter for that to be generally viable - especially for beginners who are not as adept in skates.

There are a couple of rinks here with better great control (comfortable on the ice, even in winter) and ice temperature maintained for figure skaters (usually on the Olympic surface - though one is the opposite :-P), but that is more of an exception.  Lots of skaters skate at multiple rinks, so they generally sharpen for the more problematic scenario they deal with.

Flatter blades on hard ice are more problematic than sharper blades on soft ice, so that is what the skates are sharpened for.

That's generally how I approach this, as well.  It's why I moved from 1/2" to 7/16".

Skater Body Composition and the Ice they skate on have to factor into this, as well.

[marc]

Merci à tous,

je lis avec attention toute vos réponses.

ce que savais c'était que les patineurs de vitesse ont des patins tout plats dessous c'est à dire vraiment à l'equerre.

Je sais aussi que moins  c'est creux plus on va vite mais pour faire de la danse ou des figure cela accroche moins!

Mais avez vous déjà affuter des patins à des patineurs qui font des triple saut ....et etes vous sur qu'il ne faudrait pas se rapprocher du 5.5/16  6/16 ?

Je vous rapelle pour certains que je me suis mis à affuter pour ma fille, et que moi hélas je ne patine pas!!!

Il est très compliqué de trouver de vraies réferences dans le sud de la France, et l'affutage est un monde très secret....

Donc par vos réponses , je penserais faire un petit moins creux et descendre donc dans mes 3 catégories :
1 compétitions
2confirmés
3 débutant / recreatifs

[Query]

I'm basing this on "Google Translate", because I don't know French.

>What I knew was that speed skaters have skates that are completely flat
>underneath, meaning they're square.

Not flat: Most, speed skaters I've known sharpen their own skates and create a "foil edge". That means they polish and redirect the sharpening burr to extend down into the ice. The foil edge is very thin, and is much sharp than a hollow grind, so you can push better, but is still very fast. But it is also very fragile - they sharpen every time they race.

I used to sharpen my figure skates with a foil edge, but not now, because the edge doesn't last as long.

I watched a world class skate tech work, including for people doing triples and quads. He tried to get them all to use 7/16".

Sometimes he dulled the front 1/3 of the outside edge on the jumping foot, to make it 1/1000" shorter, for skaters who needed to skid into double jumps (but non-skidded jumps are "better").

But that is just one skate tech.

Blademaster says:
https://blademaster.com/pages/skate-sharpening-101
Wissota says (for hockey?):
https://wissota.com/support/skate-sharpening-101/choose-your-radius

They both make skater weight a major factor, not skill.

[tstop4me]

Advanced and expert skaters can skate on any cut and the choice of RoH becomes a personal preference influenced by body weight, personal style, age, level of edge control, ...
Beginners and intermediate skaters can use some help by means of a flatter hollow between 19mm (¾") and 25mm (1").
The principle of RoH for beginners is simple:
The deeper the hollow, the more the skates control the skater.
The shallower the hollow, the more the skater controls the skates.
People these days are generally skating on a too deep hollow (figures and hockeys alike). The better your edge control, the shallower the hollow can be.
Good edge control makes your body adaptive enough to do those turns without the need for a deep hollow. If you are good enough, you never need those deep cuts. You will be able to cut those corners with the extra advantage of more glide.

You've got this backwards.  Advanced and expert figure skaters can benefit from the extra glide of a larger ROH for maneuvers that call for extra glide, because they have developed advanced edge control to press the edge into the ice harder (to get greater bite) when they need deep edges.  Beginner and intermediate skaters have yet to develop such advanced edge control; hence, they need the assist of a smaller ROH (greater bite) to attain deep edges, at the expense of less glide during maneuvers not requiring deep edges.  If you start beginners on a 3/4" to 1" ROH, they never will develop advanced edge control:  they will spend the majority of their time skidding, going kersplat, and sitting on the ice.  They are better off starting with 7/16" or 1/2" for a more controlled bite initially and then increasing ROH as their edge control improves.

[R45]

For 3 years I offer skate sharpening in Singapore.
First sharpening is for free as well as any new RoH they want to try.
I do this because sharpening is a hobby for me, and I love to see the progress of the skaters. I am skating myself and can see what happens when they try out different radii.
With deeper hollows there is more friction to overcome and that's the struggle for beginners because they don't have the speed and the skills. For them it feels like being a train on the tracks.
A larger RoH (19 till 25mm) is more easy for them and also allows them to sense how a proper edge should feel, and at the same time be forgiving in things like T-stops and hockey stops.
This is confirmed by the experience of the skaters using different radii.
The skaters are a mix of hockeys, figures and recreational skates.
Advanced figure skaters are a small group only, there are no expert skaters, and they prefer radii between 13mm and 19mm (½" and ¾").
Advanced freestylers on hockey skates perform best on RoH 25mm to 32mm (1" to 1¼").

[Query]

So - a conclusion might be that people can't agree on what ROH is best. Much like other sports equipment decisions.

[tstop4me]

So - a conclusion might be that people can't agree on what ROH is best. Much like other sports equipment decisions.

Ultimately, there's not one single best value of ROH (or other parameters) for every skater. There's a whole host of variables involved, and ultimately it's a matter of personal preference (skaters need to try out different values and see what they like best; and this may change over time).  And advanced skaters are more adaptable than beginner skaters.  The major issue that I see is what range of ROH (or other parameters) various people recommend for beginners, who don't know any better, and are not yet in a position to experiment and find their optimal values, because they're still struggling with basics such as balance and positioning of various body parts. 

[R45]

The major issue that I see is what range of ROH (or other parameters) various people recommend for beginners, who don't know any better, and are not yet in a position to experiment and find their optimal values, because they're still struggling with basics such as balance and positioning of various body parts.

That's correct, I only give beginners a different hollow when the are ready for it.

[Kaitsu]

Like discussed earlier in another thread, we should talk bite angles instead of ROH. Then we would speak "same langue". Like already pointed out by others, same ROH will give different bite angle if the blade thicknesses varies. This should be noted example if you change from Coronation Ace to Coronation Ace lite.

Unfortunately it is not so simple that blade thickness would be the only thing in blades which is affect to the bite feeling. My favorite topic is this &#¤%&" chrome removal grinding where they basically ruin the blades, if nowhere else. These specific blades has now 7mm ROH, since 5/16" was not deep enough and I can expect that problems still continues until she changes blades. I already have challenges to dress the wheel to enough small ROH.
https://youtu.be/bBdq03asRpI

[Query]

Very cool video!

I had assumed the reverse would be true - that the chrome removal would be done using a complex grinding wheel, giving one a slight dovetail shape, that would slightly decrease the included angle (of bite).

I wonder how typical this is for new HD Sports blades.

The video is a little bit mean to HD Sports. No matter how well you do something, it is always possible to do better. They aren't a precision machine shop, creating parts to a .0001 inch precision, and charging thousands of dollars or more per blade to do it. They are creating a relatively crude tool to cut into the ice so it doesn't slip sideways. Perhaps their prices could be lower - but people continue to buy from them in large quantities.

Of course, many (most?) skate techs use a flat stone to round off the edge itself as well, to get rid of any sharpening burr that might be formed. That also affects effective sharpness a huge amount - but doesn't change the bite angle.

Plus that type of flat stone use would create exactly the shape that the video shows, because the stone is usually tilted slightly inwards towards the center of the hollow. Is it possible that was how that shape was created, rather than the chrome removal process? And if so, we don't know whether that reshaping was done at the factory, or at a pro shop.

Alternately, some skate techs, especially those using fine grain grinding wheels, and some people using hand tools, push the sharpening burr vertically, to create a much sharper blade than the bite angle would indicate - unless you count the near-zero bite angle at the end of the created foil edge.

And I believe, but haven't proved (because my microscope isn't that good) that most sharpenings create a ragged edge, sort of like a saw blade (but less regular) that might also dig deeper, and therefore act more sharp.

Also, I think much of the time, possibly most of the time, when people think they need a sharpening, they could instead just straighten the edge.

In other words, bite angle is but one of many factors in effective sharpness. Important, but not always the most important.

And without more information, we don't know whether the inward tilt that the video shows was created at the factory, or at a pro shop.