Comparison between MK Pro vs Ace

[Bill_S]

I made a simple bending fixture from oak and some pieces of angle iron from an old bed frame. Earlier I wrote that the right MK Pro blade was not completely straight from tip to toe. This fixture was made in an attempt to straighten it.

Here's the fixture that I cobbled together. It attaches to a common vice that provides the "squeeze". The forms that bear against the blade each have a large radii, and rubber is attached to the business side of them. The arc-shaped jaws spread the load more evenly on the blade, and reduces the likelihood of a sharp local deformation.



It was scary how much the blade bent while pressing, hoping for a slight permanent yield after release. I started with a light press, checked for progress, then incremented the force each additional time.



Did I straighten the blade?



Nope. I gave up while I was still ahead. It kept springing back like nothing had happened.

I figured that I might pass its yield point suddenly and I'd have a completely trashed blade. It could have bent sharply in a small local area instead of a gentle straightening along its length. The deformation of the blade in the fixture was getting too much for me to watch, so I chickened out.

Today's experiment was a fail, but at least I didn't trash the blade. I also determined that this blade is one-tough cookie!

[tstop4me]

This video from ProSharp indicates that straightening detachable hockey runners is viable (though it looks a bit too easy):  https://www.youtube.com/watch?v=qPos5tvTJ68.  But figure skate blades (thicker, wider, brazed) are indeed tough cookies.  You really should consider requesting an exchange.

[tstop4me]

I figured that I might pass its yield point suddenly and I'd have a completely trashed blade.

The problem is that you need to pass the yield point, since you are intentionally trying to plastically deform the blade.  With your three-point nominal (three-region actual) contact jig with a curved platen, the maximum deflection is not sufficiently constrained; and so, if you apply too much stress, you can end up with a plastically deformed blade with a curvature opposite of your initial curvature (or worse).  Also, not sure what damage is done to the plating.

Another approach would be to clamp the blade between a pair of smoothly-polished, hard-faced, parallel platens.  That way, the maximum deflection is constrained, and you cannot over-correct.  Not sure whether a manual vise would work though; or whether a hydraulic press would be needed.  And I'd still be concerned about damage to the plating; and perhaps the hardened edge zone. 

But interesting experiment.  Took a lot of guts; that's for sure.  Did you try it on an old pair of blades first, or did you just go for it?

[FigureSpins]

 

[Bill_S]

Did you try it on an old pair of blades first, or did you just go for it?

No, I just went for it. Just like trying an Axel in your late 60s, you just don't have time otherwise.

This blade really wants to be skated on. It's as tough as a car spring.

[tstop4me]

It's as tough as a car spring.

According to MK (https://www.mkblades.com/about-our-blades):

"Spring Steel Memory

We only select the finest spring steel to allow for just enough flex whilst always returning to its original shape."


You've confirmed that's not empty hype.  Now, if only the original shape were flat ....

[DressmakingMomma]

Interestingly, my kid had a pair of coro aces that she regularly bent from toe pick to tail - we were told by the tech it was due to her pronation. It only happened on the left and she pronates much more on that foot than the right. The tech would clamp it down for the night and it would be straight in the morning. I can't remember how long she could go without having it straightened, but it was a few times for as long as she had that blade (probably less than a year).

[Bill_S]

Wow! How much did the blade bend?

Bending while skating sounds like how soft annealed steel (i.e. not tempered) might behave, and that's an entirely possible manufacturing mistake. But even then, the clamping overnight fix is puzzling because steel shouldn't creep (cold flow) like that at room temperatures.

Edit:  DressmakingMomma: I don't doubt your experience that the blade got straighter. The mechanism by which it straightened is what's puzzling, and may point to something else.

[Query]

Bill, I think your jig looks very cool, and looks a lot more beefy than anything I would have cooked up.

How long did you keep the blade deformed? My best guess, which may be completely wrong, is that the idea that metal deforms reversibly until you abruptly pass the "yield point" isn't quite right. I'm pretty sure that isn't true for leather - if you leave something stretched overnight, a little bit of stretch can slowly have an effect - over a period of days. Admittedly, leather probably doesn't have the crystalline grain structure that steel does, and it is possible you may need to break down that grain structure, and move around the inclusions that harden the steel by making plastic deformation more difficult, in order to alter a blade's shape much, and that might occur fairly abruptly rather than gradually. But i do know that if you flex at least some steel springs often enough, even a little, the spring constant becomes weaker, which suggests that time spent deformed is very important. I do not know whether many repeated deformations would also help, or if that would simply make the metal more brittle - it is well known that repeated deformations can make at least some steel blades brittle, though I'm not clear how that differs from mechanical tempering techniques, such as bombarding steel with metal balls, that have the opposite effect.

Part of the problem here may also be that it is partly the "Silver solder" joint rather than the metal itself which needs to deform - and it is POSSIBLE (not certain) that it breaks more easily than that wonderfully resilient spring steel. Even if that isn't true, the joint must introduce extra stresses in the other blade components when you try to unbend them.

I don't know if this will help - but "Mr. Edge" at https://geppettosskateshop.com often answers questions over the phone or email. I asked him a few once, over the phone. I am told he is one of the world's most respected skate techs. He and Mike Cunningham (the other widely acknowledged world class tech I've dealt with, the one who mentioned not unwarping by more than about 1 mm) seem to have each others' mutual respect, though they disagree on a lot of issues. Unfortunately, I don't know who the other world class techs are - I wish I did. Anyway, you can try calling "Mr. Edge" for advice.

You could also look for videos on how to unwarp steel blades. E.g. https://www.youtube.com/watch?v=CL2XxWyVfGM talks about using heat, which would really scare me - and might ruin the finish. That video also claims that blades often warp during the tempering cycles - and he sounds like he is familiar with basic applied metallurgy than most people. Perhaps your friendly neighborhood blacksmith could also give you some useful advice.

I take it that you view this as an applied engineering study, and are willing to risk breaking blades. I guess safe non-destructive testing only takes you so far on the path to ultimate metallurgical enlightenment that you seek. If an "expert" is simply someone who has learned from making the most common mistakes, than you may be following the best possible path to true enlightenment.

Imagine how much less you could have learned if you had received two perfectly unwarped blades? Be sure to thank MK for the prefect opportunity to learn!

[Bill_S]

Last evening, I switched from my old 2007 Coronation Aces to the new ones. Remember that new, the 2007 blade had a different spin rocker profile than the one that replaced it. I was curious about the difference in feel on ice.

First, the blade swap. It went mostly without any serious issues. I pulled off the old blades, then removed the silicone "gasket" between blade and boot so that I could mark the original blade orientation.



With the silicone removed from the center of the mounting plate, I could remount the original blades and carefully mark the sole where the blades fell. I used a small try-square. Holding the square flat against left, then right edges at both the front and at the heel, I drew lines on the soles as alignment guides to position the new blades when mounting them. Having already established where the old blades should be, I avoided having to adjust the new blades left or right at the rink.



Here is one blade while it was being mounted. The 1/4" difference in length is obvious at the heel.



Naturally I had to drill new holes in the heel for the shorter blades, but I also had to do a little re-drilling on the left blade's front plate. The new blade and old blade mounting holes were a little different.

I also sharpened both blades. The left blade was skatable as-is, but the right blade had one fairly dull edge. I decided to put my preferred 3/8" ROH on both blades to keep them similar to the old ones. Hand sharpening took about an hour for both.


Now the first skating report, new Coronation Aces...


The ice this morning wasn't the best because of condensation bumps, but it wasn't terrible after I used a shovel to scrape the biggest offenders flat.

Stroking, both backward and forward: Even though the rocker on the old blades had become 8' because of all the sharpenings since 2007, the new ~7' rocker didn't feel that different. I could skate just like I used to. No issues at all. I felt right at home.

Three turns: I could feel a little difference, especially if I made the mistake of getting a little forward on the blade after the turn. It's a little hard to describe the feel, but after a turn while forward on the blade, I felt like I hooked into the center of the circle fairly quickly, and ended up on toe picks easily. By the end, I had become used to it without any further issues.

Brackets: I tried just my favorites, the forward inside brackets. This experiment was a little later into the skating session, and they were not much different from what I was accustomed to. I did note on one or two examples that I had the same problem as with three turns. If I got a little forward, the edge suddenly turned deeper, and I ended on my picks. Otherwise, the feel was very close to my old Aces.

Spins: Remember that I've had troublesome spin days before, and this might just be one of them. However, I just could not get a centered spin on these new blades. The feel was very different from my old Aces. I tried mightily, but couldn't find center. I'd either fall to the inside, or be too far outside the circle. I also found that it was easy to end up too far forward onto the toe picks.

It could be the particular day and my maddening variable performance, or perhaps this is something with the blade that I have to get used to over time. This blade was NO magic bullet for spinning today. I'll give them another day or two of trials, then it's on to the MK Pros.

And I do wish that my SkateScience dance blades would come while I'm in the middle of all this testing.

[FigureSpins]

I am SO enjoying your retirement, Bill.  Blessings and thanks for sharing!

[Bill_S]

Coronation Ace testing, second day on ice

I attended this morning's freestyle session, and the ice was free from condensation bumps. The ice cut was made the evening before.

Just like yesterday, stroking and turns felt almost the same. Things that involve spinning a bit on the blade (spins, twizzles) are harder for me to adjust to. I did manage to do  better today on spins, but they are nowhere near where they should be. I also discovered that my favorite one-revolution, repeating "twizzles" were more difficult. I used to be able to string together 5 or 6 of those down the ice. I could do just two good ones, and the third started getting away from me.

The curvier rocker may have manifested itself today. There were two times where I felt (temporarily) like I was going off the back of my skates. That has happened in the past or course, but having that feeling twice in one day is more than most. I will attribute that to the rocker instead of my skating, although it could be just me.

If I keep these mounted, it will take more time to adapt to the changes from my old Aces. However, I'm getting anxious to put on the MK Professionals for a trial. Having available free time might dictate when the switch happens. Today is booked, and I've got a request for some framed photos for my sister-in-law's office.

[DressmakingMomma]

Coronation Ace testing, second day on ice
The curvier rocker may have manifested itself today. There were two times where I felt (temporarily) like I was going off the back of my skates. That has happened in the past or course, but having that feeling twice in one day is more than most. I will attribute that to the rocker instead of my skating, although it could be just me.

We all got a good chuckle the last time my daughter got new blades. She fell off the backs so many times the first week, but always while standing still and talking to her coach at the boards. She be standing there and then woosh, she would be on her butt. She didn't get hurt and also would burst into giggles. Her spins and footwork get wonky for a week or so until she finds the "spot" again anytime she has had to make a switch.

[Bill_S]

Ha - great story, and sounds so familiar.

I anticipated being completely biased toward my familiar old blades, but it's unsettling to actually feel the bias in action.

[Query]

What have you done about the warp?

[Bill_S]

The warp is on one of the MK blades. I couldn't get it straightened, so I'll mount it and try it as-is. Right now, I'm still on the new Aces.

I estimated the max curvature on that blade to be 0.020", or about 0.5mm. I suspect that's fairly common.

BTW, I did fall off the back of the Aces today. I was attempting a LBO to RFI Chocktaw with a forward ending position for my free foot, and swoosh, over the backs of the blades I went.

The whole morning's skate was a disaster, but then again, I arose at 2:47 a.m. and couldn't get back to sleep. I was a walking zombie when the 7:30 a.m. session started.

I've got some magazine stuff to work on this weekend, my wife wants to go to Columbus to shop, and I promised my sister-in-law three matted and framed photographic prints for her office. That's really eating into my blade research time!

[Bill_S]

Fourth day skating report, Coronation Aces

I spent 1-1/2 hours this afternoon on a lightly-attended freestyle session, attempting to become accustomed to the new blades. As before, I have no trouble with forward or backward stroking. Sharp turns, or on flats, it is nearly the same as before. Patterns of alternating edges forward or backward, very little change in feel.

Three turns suffer a little if my balance isn't on the proper spot. The blade wants to "turn-in" sharper than my old Aces. Overall though, the difference is small.

Brackets and counters are solid.

The 900-pound gorillas fighting me are spins and twizzles. I did manage a couple decent spins today, so I must be getting somewhat used to them. I still can't really find the sweet spot for spinning, and I'm hunting around as I go. Not pretty to look at!

It might be a few days before I have the time to mount the MK Professionals, so I imagine I'll still be on these new Aces for a little while longer. I'm getting anxious to try the other blades.

[Bill_S]

Fifth day skating, Coronation Aces

I spent 1:15 hours on the ice today. Spins were better, although nowhere near what they should be. I'm still struggling to find the right balance over this new spin rocker. I'm sure that I'd adjust in time. But being able to do a half-dozen revolutions upright is a good sign that I might be adjusting. It's slow going though.

Freshly Zammed ice today felt slippery. I was able to hold deep edges. It surprises me sometimes that I don't just lose grip and fall, but I'm "riding on rails". Speed was good.

I expected to feel a substantial difference in speed between these new sub-7' rockers and my old ones flattened to 8' after years of sharpening. Frankly, the ice condition makes much more difference in speed than this subtle change in rocker. Maybe if figure skating were a contest of speed, the micro-advantage of a flatter 8' rocker would show, but I just can't feel it.

But I certainly can feel the curvier rocker on occasion, I just can't feel any slowness or additional drag.

[tstop4me]

I expected to feel a substantial difference in speed between these new sub-7' rockers and my old ones flattened to 8' after years of sharpening. Frankly, the ice condition makes much more difference in speed than this subtle change in rocker. Maybe if figure skating were a contest of speed, the micro-advantage of a flatter 8' rocker would show, but I just can't feel it.

But I certainly can feel the curvier rocker on occasion, I just can't feel any slowness or additional drag.

Yeah, there are a lot of variables in ice skating; and skaters' experiences vary.  When I switched from a 7' main rocker (Eclipse Aurora and Wilson Coronation Ace) to an 8' main rocker (Paramount version of Wilson Gold Seal), I was pleasantly surprised at the faster glide; I wasn't really expecting much of a difference.  One of my warm-up drills is stroking backwards down the whole length of the ice.  The first time on my Paramounts, I actually overshot the red line and hit the boards (fortunately not too hard); something I never did before.  And on my Figure-8's, right off I had no problems routinely completing full circles on a single push, with momentum to spare; previously, I'd often just barely complete a circle, petering out at the end.  That gave me a great deal of satisfaction.  My coach was real happy to see me finally do decent Figure-8's.  My cross-overs also picked up a lot more speed; a bit scary at first.

[Query]

I expected to feel a substantial difference in speed between these new sub-7' rockers and my old ones flattened to 8' after years of sharpening. Frankly, the ice condition makes much more difference in speed than this subtle change in rocker.

Is it possible that your old 8' rocker blades didn't let you take full advantage of the faster speed and longer glide a flatter rocker should have given you, because you had lost enough metal that your toe pick interfered with getting a full length stroke?

Those nice deeply leaned edges that you are managing should also make you faster. I believe that a less worn blade lets me lean further, because I am further off the ice (again, more metal) without impinging too much on the side of the boot.

I personally think blade sharpness makes at least as big a difference as rocker.

It is great that you are adapting well to the new blades.

It's a shame there is no economically practical way to vary one shape variable at a time, and alliteratively converge on the best choice.

[Bill_S]

I would have known about any toe pick touchdown, at least when the noisy dehumidifier wasn't running.  I'm sure that wasn't the issue.

I completely agree that my skates feel faster right after a sharpening. They can get downright "slippery" feeling. That is easy to notice.

I put in 45 minutes of skating today, but with arthritis pain flaring up in my left foot, I left early. While there, I skated like an elderly person doing safe things, so nothing of value to report.

Meanwhile... I thought that I'd better get an 8' rocker blade to test. I placed an order with Kinzie's Closet yesterday. I'll start a new thread when the pair of blades arrives.

The MK Pros are up next to complete this thread before I try the new 8' blades.

[tstop4me]

Meanwhile... I thought that I'd better get an 8' rocker blade to test. I placed an order with Kinzie's Closet yesterday. I'll start a new thread when the pair of blades arrives.

A cliffhanger?  What blades did you order?

[Query]

Just as long as it isn't an Ultima. Most of them have a much more curved and shorter spin rocker, and take a lot of time to adapt to (I took over a year), because you keep accidentally touching the toe pick. Even once you get used to it, you have a shorter roll of the blade, giving you less speed and power. OTOH, it is easier to reach the toe pick - which is good for jumps, and if you do them, pivots, and MAYBE for other things.

It's the only thing I dislike about my Ultima blades, but it is a doozy. I wonder if any of the newest crop of Ultima blades have a shape more like the MK and Wilson blades...

Incidentally, on the devices sold that are supposed to measure blade wear, e.g., by checking how far you can roll before the toe pick touches, or how long the region between where the toe pick touches on a rigid flat surface (which ice isn't) and where the farthest forward part of the rest of the blade is, they generally say Ultima blades are already worn out when new, because of the shape difference. I think they were designed for typical MK and Wilson blades.

So far the fastest and longest gliding figure skating blade I have found is the MK Dance. (But speed skates. and sometimes to some extent hockey skates, are a lot faster.) But for some reason, they are rather pricey. Maybe it is because MK gives away blades to very high profile elite skaters and coaches, which in turn might help explain why almost all the Olympic ice dancers use them, even though the Ultima Dance blades (last I knew) are much more reliably shaped and less likely to be warped.

But it will be very interesting to see how expanding your selection affects your blade reviews. And whether you end up deciding you still like best what you have used for many years.

Have you thought of going to a pro shop who's manager you know well enough, and tracing many types of blade, and imposing the rocker profile on cheap blades, for test purposes? I have thought of doing the measurement part. In part because I would also love to know how rocker profile varies with blade length within the same model. My suspicion is that the front of the blade is identical, because that is what the chief sharpener for Riedell, just before they came out with the Eclipse line, thought was true. I wonder if that actually makes sense, or whether the shapes, including spin rocker length, tail extension, and rocker radii, would be better off being scaled.

[Bill_S]

Jackson UB40 Protege

Measurements and comments will follow in a separate thread.

[MCsAngel2]

Next purchase....Gold Seals??