Is it sharpenings, usage, or both that reduces the rocker? | Golden Skate

Is it sharpenings, usage, or both that reduces the rocker?

christy

On the Ice
Joined
Jun 17, 2014
I have a pair of Jackson Matrix blades that have been used for around 3 years for around 3 hours a week and sharpened around 20 times and the rocker is now completely flat. I always assumed that the rocker was flattened by sharpening but 20 sharpenings doesn't seem that much so I was wondering is usage also flattened the rocker?
 

tstop4me

Final Flight
Joined
Oct 2, 2015
Country
United-States
I have a pair of Jackson Matrix blades that have been used for around 3 years for around 3 hours a week and sharpened around 20 times and the rocker is now completely flat. I always assumed that the rocker was flattened by sharpening but 20 sharpenings doesn't seem that much so I was wondering is usage also flattened the rocker?
Before I answer, some more info would help. By "rocker", do you mean the main rocker, the spin rocker, or both? Which specific Matrix blade (in particular, the Legacy or one of the more advanced blades)?

ETA: Also, what ROH (radius of hollow) do you use, and what level of skating are you at?
 

Nimyue

On the Ice
Joined
May 15, 2018
If they were sharpened on a hockey blade sharpener, the rocker can be removed in one sharpen. If someone is just not a good sharpener, they can ruin the rocker in one sharpen.
 

concorde

Medalist
Joined
Jul 29, 2013
I am thinking that 20 sharpenings is about the life of a good blade.

From taking with our fitter, I get the impression my daughter's blades will only last about 18 months. She skates ~2-3 hours per day, 5-6 days a week. Her blades get sharpened about every 5 weeks. We only use a very trusted sharpener.
 

Ic3Rabbit

Former Elite, now Pro. ⛸️
Record Breaker
Joined
Jan 9, 2017
Country
Olympics
All of the above. But please, don't let just anyone sharpen your blades.
 

christy

On the Ice
Joined
Jun 17, 2014
They've always been sharpened by the same sharpener and it's been a gradual flattening of the blade, not suddenly it's flat / loss of the rocker. By rocker I mean the main rocker, not the spin rocker, although that's fairly flat now too. In terms of time I'm not surprised the blades need replacing, however it was the fact that they hadn't had that many sharpenings compared to friends who have their carbon blades sharpened every 2 weeks, and whose blades have lasted a similar time.
 

tstop4me

Final Flight
Joined
Oct 2, 2015
Country
United-States
They've always been sharpened by the same sharpener and it's been a gradual flattening of the blade, not suddenly it's flat / loss of the rocker. By rocker I mean the main rocker, not the spin rocker, although that's fairly flat now too. In terms of time I'm not surprised the blades need replacing, however it was the fact that they hadn't had that many sharpenings compared to friends who have their carbon blades sharpened every 2 weeks, and whose blades have lasted a similar time.
(1) Going by the numbers in your Post #1, you skate ~3 hrs/wk. Assuming you skate all 52 wks/yr for 3 yrs, you’ve skated a total of 468 hrs. With a total of 20 sharpenings, that comes out to an average of only 23.4 hrs per sharpening (if you skate less than 52 wks/yr, the number would be even less). That sounds short to me, even for carbon steel blades. The advanced Matrix blades have AUS8 stainless steel runners; they should last much longer than that. Even the Matrix Legacy, which uses a lower grade of stainless steel (420J), should last longer than that.


(2) With commercial sharpeners, a very good tech will remove ~0.005” per sharpening (assuming you don’t damage your edges substantially; if there is substantial damage, more would need to be removed). For 20 sharpenings, that would be ~0.10” total removed. That’s getting close to end of life for most blades. Average techs will remove more, and bad techs will remove a lot more; so your blade is probably at end of life.


(3) Assuming you use a typical freestyle radius of hollow (ROH) in the 3/8” – 1/2” range, you won’t wear down an edge completely before the blade needs to be resharpened. Therefore, wear through use won’t substantially change the main rocker.


(4) With most commercial sharpeners, the tech guides the blade by hand; i.e., maintaining the rocker is entirely a manual operation. If your main rocker has been flattened, it’s most likely due to the tech. Note: the spin rocker will flatten as a matter of course. The diameter of most grinding wheels is sufficiently large that a region of the blade immediately behind the drag pick does not get sharpened. As the main rocker gets ground down, the spin rocker flattens out. Some skilled techs with the right equipment can reprofile the spin rocker with a cross-grinder and trim down the toepick to extend the life of the spin rocker.
 

christy

On the Ice
Joined
Jun 17, 2014
Wow, thanks for the detailed explanation tstop4me. So 20 sharpenings would mean end of life for most blades? That's really useful to know so I can plan ahead. I've been getting my blades sharpened when there's an opportunity but will now try to allow more time between sharpenings.
 

tstop4me

Final Flight
Joined
Oct 2, 2015
Country
United-States
Tstop, you are a wonderful source of knowledge on blades. Thank you for your work ;)
You're very welcome. Glad to be of help. Thanks for your kind words. Now if only I were as good a skater as I am a physicist ....
 
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