Wear on 11-1/2 year old blades

[Bill_S]

I skate in Coromation Aces. The pair that I currently use was purchased new in late 2007 with a new pair of boots. That's 11-1/2 years of wear on them, but they were never machine sharpened. I've always used a Pro Filer to sharpen them. I estimate that I sharpen about 4-5 times per year.

I'm having a bit of trouble spinning these days, and the cause is probably me. However, the recent frustration did cause me to revisit the blade rocker out of curiosity.

When I purchased the new skates, I traced the blade profile onto a sheet of paper, and put it away for reference. Today, I did two things.... 1) I placed the skate blade edge against the old tracing to see how much has been worn away by skating and sharpening, and 2) I traced the blade as it is today for some Photoshop work.

Here's the blade held against the tracing made in September of 2007. I aligned the toe pick and the tail of the blade to see how the working part compared.

(On some computers, you can click the picture to enlarge it)



Here's a tight crop of that area...



I made a rough measurement with a steel engineer's ruler and the wear is less than 1/16th of an inch over the years. However, the middle part is worn, but the tail and the part just before the toe pick is not. This flattens the blade rocker.

Here's a Photoshop-created comparison between the old and new tracings where you might be able to see the worn part and how it fairs into the rest...

(click to make big on some screens)



My conclusions are that the amount of wear is not bad at all, but the subtle reshaping of the rocker might have an adverse effect on my spins. Maybe I CAN blame the equipment, or then again, maybe it IS just me.

Time for new boots and blades to tell whether I'm to blame, or if the equipment is.

[Christy]

I recently replaced a pair of blades that had been sharpened about 20 times by a very well respected sharpener and the rocker was almost flat. It sounds like your's have been sharpened twice as many times.

[Loops]

My blades have also historically been machine sharpened, my old Prof's by a well respected sharpener.  (I won't include my blades since moving to France, because the sharpening is 'bof' as we say here).

I've never traced mine, like you did, but I could visibly see that they were flat as a pancake.  I've noticed the same with some friends of mine here, who are also on old blades (but again, 'bof' sharpening). How they turn, twizzle, and spin, I've no idea.

I would be very curious to see someone who has traced the profile of their new blades, then again after some number of sharpenings (even better if they did it periodically), just to see how much faster the machine sharpening wears, and whether or not its more pronounced over the rocker (my working hypothesis would be that it is more pronounced).

I have to say, I've been profiling these new blades (CorDance), I've sharpened 3 times since september....  My jury is still out.  Perhaps I'm not spending enough time sharpening them, but I'm having, right now, to really resist hard the temptation to let our one competent guy have a go at them.  I just am not getting the grip I like on the ice.  Before they wrecked my old blades though, I was also one of those who sharpened every 20 hours or so.

[tstop4me]

I have to say, I've been profiling these new blades (CorDance), I've sharpened 3 times since september....  My jury is still out.  Perhaps I'm not spending enough time sharpening them, but I'm having, right now, to really resist hard the temptation to let our one competent guy have a go at them.  I just am not getting the grip I like on the ice.  Before they wrecked my old blades though, I was also one of those who sharpened every 20 hours or so.

I assume you're talking about your results with the Pro-Filer (http://skatingforums.com/index.php?topic=6837.0 , Post#12).  So far, my experience with the Pro-Filer is that I haven't been able to achieve as deep a hollow as that achieved with an equivalent proper machine sharpening.  I splurged on a hollow depth indicator (HDI) gauge (http://pro-filer.com/hdi/).  With a 3/8" radius of hollow (ROH) machine grind by a competent tech, the measured depth of hollow (DOH) is close to the expected value.  With the 3/8" ROH Pro-Filer, the measured DOH is consistently less than the expected value.  I'm working on improvements to my Pro-Filer sharpening; I'll see if they help.  I also improve the bite with steeling the edges, as discussed here:  http://skatingforums.com/index.php?topic=8207.0.

By the way, does the Coronation Dance have a thinline profile?

(Sorry for the digression from the OP).

[Loops]

Yes Tstop, you assume correctly. No the CorDance are not slimline.

[tstop4me]

....
I made a rough measurement with a steel engineer's ruler and the wear is less than 1/16th of an inch over the years. However, the middle part is worn, but the tail and the part just before the toe pick is not. This flattens the blade rocker.
....
My conclusions are that the amount of wear is not bad at all, but the subtle reshaping of the rocker might have an adverse effect on my spins. Maybe I CAN blame the equipment, or then again, maybe it IS just me.

Time for new boots and blades to tell whether I'm to blame, or if the equipment is.

(a) Even if, during a sequence of sharpenings, you perfectly maintained the entire rocker profile from just behind the drag pick all the way out to the tip of the heel, you would still eventually degrade the spinning characteristics of the blade.  Assuming you don't accidentally damage your drag pick, the amount of wear on your drag pick is not significant.  As you sharpen the edges, you remove metal along the edges, and the vertical distance between the tip of the drag pick and the edges increases.  Consequently, the sweet spot moves longitudinally away from the drag pick towards the heel, and the heel lift decreases ... negatively affecting your spins.  Of course, any unintentional flattening of the spin rocker will increase the negative impact.

If sharpening has not removed too much metal (and I believe your 1/16" removal is not too much), you can move the sweet spot forward again by trimming the drag pick.  Some skate techs I know grind down the drag pick a bit, and then use a cross-grinder to touch up the region just in back of the drag pick.

(b) Your Pro-Filer results over the course of a decade+ (less removal near the toe and heel than near the middle of the blade) are interesting.  I've thought about that potential consequence.  Near the middle of the blade, for each sharpening pass, a localized region of the blade gets ground by approximately the entire length of the stone.  Near the toe of the blade, however, the drag pick serves as an obstruction, and a localized region of the blade gets ground by approximately only half the length of the stone.  Near the heel of the blade, the same holds unless you pull the stone from toe to heel and pull the Pro-Filer completely clear of the blade.  So you would need extra localized passes near the toe (and maybe near the heel) to compensate.

[Bill_S]

I've occasionally dressed the tail and the blade area behind the pick even more than the rest to overcome just what you say.

That leads to a conclusion.... I didn't do it enough over the years.

I'm not about to grind the tail down 0.050" to 0.060" inch by hand. I can remove ~0.001" per hour by hand, so I'd spend a whole working week in the attempt.

That's when I wish that I had a powered sharpener for aggressive metal removal. Then again, it's probably time for new blades anyway. I got MANY more years of usage from these than most people.

I'm being like the driver complaining about a new rattle in a car that has 250,000 miles on the odometer.

Loops: When sharpening, lightly slide a fingernail against the side of the blade toward the edge to feel if a slight burr is developing. It's easy to feel it, and that means that your sharpening is adequate in that spot. If the fingernail slips past the edge of the blade with no resistance, you haven't sharpened enough.

I feel for the micro-lip or burr along both sides, and front-to-back to make sure that the sharpening is even. I allow at least 45 minutes to an hour to get a wicked-sharp edge.

[Loops]

Will try feeling for it. I was looking, but visually and don't see much of anything. Is your timing of 45 min to an hour per blade or overall?  I assume overall, but want to be clear. I might spend about 15 mins per blade. But i don't time it. I have been suspecting that I don't spend enough time.... live and learn!!!

[Bill_S]

That's overall time for both blades.

You also need a beginning hollow that's close to the ROH of the ProFiler. If not, it will take extra work rounding out the hollow until you reach the edges. Once you have reached good edges by hand, maintaining them is not difficult, but does take time.

The fingernail test used with your diamond stone should tell you when to switch to the polishing stone.

[tstop4me]

Will try feeling for it. I was looking, but visually and don't see much of anything. Is your timing of 45 min to an hour per blade or overall?  I assume overall, but want to be clear. I might spend about 15 mins per blade. But i don't time it. I have been suspecting that I don't spend enough time.... live and learn!!!

* Heed Bill's advice to feel for the burr with your fingernail.  Otherwise, you can get a nasty cut.

* I've found that if there is too much gap between the guide block and the blade, I don't develop a well-defined burr.

* You might find it useful to track the total number of strokes.   Since we stroke at different rates, it's the total number of strokes (among other variables) that determines how much material is removed.

[Bill_S]

To clarify the fingernail test, I thought that an illustration would be in order...



Don't use much pressure. The nail should glide up lightly.

[Query]

First of all, I think you have done a great job of prolonging the life of your blades. About how many hours have they had on the ice?

If you aren't careful, sharpening tends to blur the "sweet spot" - the place where the rocker curvature abruptly changes from the main (back) rocker radius to a shorter (front) spin rocker radius. That's true whether you use a hand tool like Pro-Filer, or the bench power tools like pro shops use. Especially if you use long continuous strokes of uniform pressure from front to back and/or vice-versa - usually a great technique, but occasionally, you may want to re-emphasize the sweet spot. You may even want to move the sweet spot to the position on your foot you want to spin over.

My personal feeling is that it is easier to spin - though I am awful at it - if you can "feel" the place where that rocker changes, and spin there. Otherwise it is too easy to rock forward and back, because you can't feel where you are on the blade. Of course many good spinners don't need this - they can feel exactly what their body is doing, and don't need this type of help. I've seen some people, especially kids, spin incredibly well on incredibly badly sharpened blades. I don't know how they do it.

Depending on the blade design, the main rocker is approximately 7' - 8' radius, and the spin rocker, probably just ahead of the balls of your feet, has a .75' to 2' radius. If I remember correctly, many Ultima blades have about a .75' spin rocker, and many MK blades have about a 1.5' - 2' spin rocker. Some Wilson blades have two sweet spots up front - separating 3 different zones of rocker radius. I don't know whether the original Coronation Ace does.

The method I think you once posted of measuring the rocker radius using a straight edge may not accurately measure the short spin rocker zones, because it requires too long a length of uniform rocker radius. That's why I instead try to place the blade against curved lines like
  http://mgrunes.com/boots/rocker.png
Print it. You may have to cut away the area around the desired curve so you can lay it right alongside the edge of your blade. Unfortunately, if your printer is in poor condition, it may not print with uniform curvature. For calibration purposes, you could check your printer scaling - the horizontal grid lines will be .25" apart, and the curves will be .35" apart on the x-axis. It may help to use a magnifying glass to see the very small blade deviations from the printed curve.

However, I'm not sure the exact rocker radii matters all that much, for most purposes. They can even be a bit non-uniform, though I personally try to avoid that. I believe it is the sharp transition between two zones, creating the feel-able sweet spot, that matters most. (A sharp transition at the sweet spot may also help you initiate turns. Though, at least for me, initiating turns is easy - checking turns is the hard part. Alas, I don't know if any blade characteristic makes checking turns easier.)

I see no reason why the back of your blade should matter that much, because most of us don't spin there. I wouldn't grind down the back. All that would really do is give you a smaller main rocker radius, which would make it slightly harder to distinguish from the front spin rocker area - in other words, the opposite of what you want. It might also make the blade slightly slower. And doing it with a Pro-Filer would wear out that expensive tool a lot.

I occasionally re-emphasize my sweet spot in two ways - I reduce the spin rocker radius, especially near the sweet spot, and I add a very slight convex direction change, that makes it even easier to feel. AFAIK, that direction change is not incorporated into any factory blade shapes - AFAIK, it is my innovation. Think of it like the cusp at the bottom of the top - it provides a point to spin upon. Or like spinning barefoot on the ball of your foot, with the front of the foot bent upwards, just like it probably is inside your boot.

The very small amount of direction change I seek isn't really visible, and I can only feel it when I skate on it, not with my fingers, or only the ghost of a sensation.) You MIGHT be able to see it in the reflection of the blade, at just the right angle, but don't count of it. Too big a direction change might make it harder to stay on that point, so is counterproductive.

I do both things by placing the Pro-Filer with the back of the cylindrical stone at the spin rocker, and the front of the tool closer to the toe pick. I push forwards towards the toe pick (I tape the toe pick, so I don't mess it up!), increasing the force as I go. Sometimes I tilt the Pro-Filer slightly forward, to get a stronger direction change. If there isn't enough space to place the entire Pro-Filer stone ahead of the sweet spot, you may have to use more tilt, so the back of the tool doesn't round off the sweet spot again.

Then I turn the Pro-Filer around 180 degrees, and do it again, because the Pro-Filer is an imperfect tool, and stroking it in the opposite direction evens out the length of the inside and outside edge.

Then I rotate the skate 180 degrees, and place the Pro-Filer so the back of the cylinder is at the sweet spot again, but the front is towards the back of the blade. And I do the same thing, stroking towards the back of the blade, increasing pressure as I go, and again with a tilt away from the sweet spot. And do the 180 degree exchange again.

As always, use a flat stone or equivalent to straighten and perhaps polish the edges, so they point vertically, rather than to one side.

Good luck. I bet these things PARTLY solve your problem. But, if your body is less sensitive to blade shape changes than it used to be, or your inner ear doesn't detect balance as well as it used to, or you have lost some of your fine motor control, or you have lost your muscle tone so your body flops around like a wet noodle, nothing can fix those things that I know of.

Many good professional sharpeners occasionally re-emphasize sweet spots, to make the curvature change sharp again. Some change the location of the sweet spot to better match the anatomy and preferred point of spin of the skater too. But I don't know if any of them also create a slight direction change there like I do.

As tstop4me says, you may eventually feel a need to shorten your toe pick. So it doesn't interfere too much. Say, in another 10 years? 

By the way, if you brush your finger very lightly ACROSS the width of the blade rather than ALONG the length, you probably won't cut yourself, and can feel the edge much better. But I hesitate to tell that to kids, because they can be careless with their fingers. Even some adults don't understand what "very lightly" means. It works with knife edges too, even ceramic knife edges, and if you are super-super-careful, with razor blades. You can feel sharpness, and you can feel if the edge has been bent over.

[Bill_S]

First of all, I think you have done a great job of prolonging the life of your blades. About how many hours have they had on the ice?

Sorry for the delay in response. We had a bad power outage Sunday through Monday, and I'm just now getting caught up.

I have an estimated 2,500 hours on these blades. When they were new, I skated 12-15 hours per week, but now I'm down to 7 per week.

Our rink is seasonal (open 7 months), so things slow down a lot in the summer when I have to travel to skate.

[Query]

That's a lot of hours!

One good skate tech (Mike) told me that 40 hours on ice / sharpening with .003" removal is "normal", with a lot of variation, of course. So the average person using a reasonably good professional skate tech would use up blades after about 33 sharpenings, if they throw away the blade after .1" is used - pretty common, especially if the skate tech doesn't try to trim the toe pick. So a 1200 hour lifetime would be about normal, for most people, using a reasonably good tech - again with lots of variation.

But hand tool sharpening should use less steel, unless you do something extreme, especially if you sometimes straighten instead of sharpen, so longer lifetimes are reasonable.

I confess I spend a lot less than Bill's 45 minutes to sharpen by hand. More like 5, tops, for both blades. Maybe I don't usually need ultra-sharp, or I sharpen more often.

Anyway - do you (Bill) try to maintain the abrupt change at the sweet spot? If not, that could easily explain spin issues. You can maybe see whether the abrupt curvature change has become gradual by looking at how the blade tracings have changed in detail, near that spot.

P.S. Lest everyone reading this thread goes out and buys sharpening tools, I suspect most of you spend substantially more money on lessons, injuries, ice time, costumes, primping, off-ice training, fees, and transportation, than on buying and maintaining blades.