Comparison between MK Pro vs Ace

[Query]

Mike C once told me he returns blade pairs with significantly more than .001 inch warp, because, when you straighten a blade, it sometimes breaks. But it's your call. Also, Mike is unusually picky, and returned about 15% of the blade pairs he was sent, while I watched him work for a while - he told me that the blades he returns often get sent out to other retailers.

But you could try to find out from the retailer if the blades can be returned. Sometimes HD Sports (owns MK and Wilson) is willing to pay return shipping costs, if the flaws are bad enough. If the retailer says no, you could contact the manufacturer.

I used to have a Coronation Ace blade pair which was warped in at least one blade - but I didn't measure how much. But at least one skate literally got hot when I skated, presumably from the extra friction. And they were a lot slower than the MK Dance blades I replaced them with - though that was supposed to be true, even though MK Dance blades are shorter, because MK Dance blades are ground slim line at the bottom. (Maybe the rocker profile and less toe pick configuration help too.)

I'm not certain of the other consequences of warped blades, in terms of how they perform, if you don't straighten them, but some people claim it does affect skating in other ways.

BTW, Mike once worked as a welder, and also did some work in a machine shop. He believed that blade warping probably occurs during the "silver soldering" process (which he thought of as a form of welding) that is used to hold the runner to the rest of the blade. Neither Ultima Matrix nor Paramount runners are attached using form of welding or soldering, which might explain why they produce very few warped blades. (Though I have seen some warped low end Jackson blades that were rivetted together - not sure how they got warped.)  OTOH, silver soldering produces very clean looking joints, which you can clearly see on high end MK and Wilson blades, and skating is an appearance-oriented sport.

If you do decide to de-warp the blade anyway, maybe you don't need a jig. What if you put something smooth and straight next to the blade on both side, in a vice, with a gap on one side? Do it slow, with as little thickness as you can, to reduce the amount of inverted warp you need to straighten it. But be careful to cushion it enough that the grooves in the vice don't leave a mark on the blade, or mess up the edge. (I haven't tried it.)

[Bill_S]

The jig that I had in mind was to be something that slipped over the jaws of a vice. It might be a while because some paying-job shop work has to be done first. If it gets done, rest assured that I'll have lots of photos of it and how it works (or not).

Overall Fit and Finish

I'm about done assessing the merits of each of these blades, so I thought that I should address any differences in fit and finish - mostly cosmetic issues.

Both blades have wonderful looking fillets where the blades are brazed to the mounting plates. I have never seen a bad joint in a blade over the years, although I'm sure that some get past the manufacturer. Here's a close-up of the joint on a Coronation Ace heel joint. The MK Pro blades looked great too.



The MK Professional front mounting plate on the right blade is very rough on the edge. It wasn't smoothed before plating. In the second photo below you can also see the cupped-shape of the mounting plate, typical of both MK blades.





Compare the above with the Ace...





The more I think about mounting them, the more I prefer the flat mounting plates on the Aces. If not mounted with care, the cup-shape on the MK could be a repository for water, right next to the leather.

One Ace blade had a little irregularity at the toe pick area. I'm not sure what caused this, but it shouldn't cause any issues.



Both blades were rough on the upper part of the blade edge. I haven't seen this sort of irregularity before, and it doesn't look typical of a stamped part. This might be a clue how the blades are rough-cut to begin with, but I'm at a loss what caused this sort of surface. Regardless, they plated right over it. Again, it's just cosmetic being out of sight. It's interesting to note that my Aces from 2007 are cross-ground in this area. They are a bit rough too, but from a grinding operation.



Both blades had identifying information and blade size etched onto the sides of the blades. It is not raised text as you would get with a silkscreen. Laser engraved? Chemical etch? In the past, Wilson blades had blade size stamped into the underside of a mounting plate.

[Query]

I don't worry so much about how flat the mounting plate is. Shim it to fit - you can even use tape, provided it is a reasonably stable type of tape. (Don't use duct tape. The glue gradually peels off, and it changes shape. I've used cloth first aid tape for somewhat similar purposes, precisely because it's pretty stable - though I'm not sure if it's flexibility would be a problem on high jumps.)

But I think Sid Broadbent has it right - CoPlanar mounts are the logical way for the industry to go. Seems so obvious. Mounting would be a lot faster and easier. E.g., you could shift the mount position without re-shimming the blade.

It would be easy to sand the bottom of a boot flat. But much harder to modify blade mounting plates to be CoPlanar.

I once asked a blade manufacturer's rep why they didn't go CoPlanar. They said they wouldn't match most of the boots. So I asked a boot maker why they didn't make the boot bottoms CoPlanar. They said they wouldn't match most of the blade mounting plates.

Huh. I guess, sometimes, a sub-optimal ill-defined standard is seen as better than no standard at all.

[tstop4me]

Mike C once told me he returns blade pairs with significantly more than .001 inch warp, because, when you straighten a blade, it sometimes breaks.

I'd be interested in what he considers "significantly more than .001 inch warp"?  Does he actually measure down to .001 inch warp accuracy?  What tool does he use?  I'm familiar with tools used in high-precision machine shops, but I would think the $$$ would be beyond that of skate shops, even high-end skate shops.

[tstop4me]

I don't worry so much about how flat the mounting plate is. Shim it to fit - you can even use tape, provided it is a reasonably stable type of tape. (Don't use duct tape. The glue gradually peels off, and it changes shape. I've used cloth first aid tape for somewhat similar purposes, precisely because it's pretty stable - though I'm not sure if it's flexibility would be a problem on high jumps.)

But I think Sid Broadbent has it right - CoPlanar mounts are the logical way for the industry to go. Seems so obvious. Mounting would be a lot faster and easier. E.g., you could shift the mount position without re-shimming the blade.

It would be easy to sand the bottom of a boot flat. But much harder to modify blade mounting plates to be CoPlanar.

I once asked a blade manufacturer's rep why they didn't go CoPlanar. They said they wouldn't match most of the boots. So I asked a boot maker why they didn't make the boot bottoms CoPlanar. They said they wouldn't match most of the blade mounting plates.

Huh. I guess, sometimes, a sub-optimal ill-defined standard is seen as better than no standard at all.

Yeah, it's like the number of hotdogs in a package not matching the number of buns in a package.  Meat producers and bakers can't seem to agree.

But I was hoping that once a single company controlled manufacture of both boots and blades we would see progress towards a more rational mounting geometry (such as CoPlanar).  Riedell and Jackson now manufacture both boots and blades (I don't know for how long, but at least 5 yrs), and they don't appear to be moving in that direction; a big disappointment. 

[Bill_S]

About the MK Pro "dished" mounting plate - I would continue to use RTV silicone sealant, probably a hefty dollop, on the bottom of the plate before mounting. It would squeeze into the shape of the space between the blade and sole to provide continuous contact.

I've done that for my current skates, now 12 years old, and there's not even a hint of water damage to the sole.

I know that you've visited the Precision Blade Honing Enterprises web site. They use an epoxy putty as the "gasket" between the shape of the sole and the mounting plate.

[Query]

I'd be interested in what he considers "significantly more than .001 inch warp"?  Does he actually measure down to .001 inch warp accuracy?  What tool does he use?  I'm familiar with tools used in high-precision machine shops, but I would think the $$$ would be beyond that of skate shops, even high-end skate shops.

He's a fanatic. I'm sure he has the tools.

I didn't actually see him measure warp accurately. He touched the blades with a precision straight edge, and looked for light to shine through. After 50+ years working in and around ice rinks, he has a good feel for such things. He's done other precision measurements, like compare the relative thickness of the metal plating and the "chrome relief" zones on each side of a blade (he says MK/Wilson sometimes mess that up, creating potential sharpening issues). For that matter, he's done some work in machine shops.

That isn't as crazy as it sounds. Bringing out such tools and parading such knowledge reassures his customers that he will bring the benefit of his fanaticism and expertise to their problems. I watched high profile athletes walk into his shop after flying half-way around the world. Many such people don't just want someone who is merely competent. They want a fanatic, to match their own degree of dedication.

BTW, anyone could improvise a simple long-wise warp measurement tool themselves. Take a good quality metal straight edge, lay it against the blade, and see if you can slip a piece of thin tracing paper anywhere under the straight edge. You can estimate the thickness of the paper, by measuring a stack of 100 or 200 sheets. (I haven't figured out how to accurately measure twist warp.)

[tstop4me]

About the MK Pro "dished" mounting plate - I would continue to use silicon sealant, probably a hefty dollop, on the bottom of the plate before mounting. It would squeeze into the shape of the space between the blade and sole to provide continuous contact.

I was at a pro shop today.  I looked at the sample Coronation Ace and MK Pro on display [only one blade each, not a pair].  On visual inspection, the sole plate on the Pro was as flat as the one on the Ace.  Perhaps the cupped or dished sole plates on your Pros are indicative of manufacturing variation (or defect).

[Loops]

.... or could it be older stock? 10.25 is a reasonably common size, so it's unlikely to be old, but you never know.

[Bill_S]

Just so everyone can get an idea of how dished the front plate is on the MK Pro, here are two photos. Holding a straightedge against the plate easily shows daylight in both photos - left to right, and fore to aft.





I'd estimate that the deepest part is about 3/32".

It looks as if it is an intended feature, but it begs the question "Why?"

And why is the sample observed by tstop4me different? A slipstream design change? Which is representative of the current blade?

[Bill_S]

I thought that it might be interesting to show my old Aces in their current condition. This may help explain possible differences in feel when I get the new skates going.

[Click picture to make bigger]



The toe pick end is on the left, tail is on the right. The vertical scale is greatly expanded.

I note that about 0.10" of metal has been worn away over the 12-years of usage, with hand-sharpening only. I also calculated the rocker main radius to be at 8' after all the sharpenings. That's not surprising.

It will be a significant change going to the nearly 7' rockers of the new blades.

If these were new, and without the wear-related rocker radius increase, they'd probably be closer to the MK Pro profile than the new Ace.

[nicklaszlo]

It is unlikely the blade markings are laser engraved.  Etch or anodization processes seem more likely to me.

Surely mounting the blade warps it more than 0.001".

[Bill_S]

I would also expect that mounting puts enough force on the blade to slightly warp it. With un-matched mounting surfaces, it would be hard to avoid.

There is the change of thickness along the length of both of these blades, and my old pair too. If one side is flat to within 0.001", then the other side cannot be.

0.001" is an exceedingly tiny amount.

Edit: Fixed typos. I shouldn't post in a hurry when my wife is calling for me to come upstairs.

[tstop4me]

Surely mounting the blade warps it more than 0.001".

I would also expect that mounting puts enough force on the blade to slightly warp it. With un-matched mounting surfaces, it would be hard to avoid.

There is the change of thickness in both of these blades, and my old pair too, to remember. If one side is flat to withing 0.001", then the other will not be.
0.001" is an exceedingly tiny amount.

I'm glad others here appreciate how small a tolerance .001" is; difficult to measure ... and even more difficult to achieve in a consumer product.  Especially in view of the aspect ratio of a blade:  a thickness of only about .160" or less, but with a length of up to about 12" or more. 

Note there are three related parameters:  thickness variation, bow, and warp.  If you try to measure bow and warp of a blade to an accuracy of .001" by placing the blade in direct contact with a reference surface, the reference surface would need to be flat to           
+/- .0001" over a 12" or more length.

[tstop4me]

It certainly appears in the graph that the Ace (in red) has a compound curve (3 radii?). It has a bulge at ~1.5" to 3" from the root of the drag pick. The MK Pro curve (green) appears to be a simpler two-curve shape.

BTW, the Ace rocker radius in the 2"-3" area is calculated to be 14.8". The tightest I found so far on the MK Pro is 18.75" in the 2"-3" area. This goes counter to some of the charts that I've seen at retail web sites which claim that the MK Pro has a smaller spin rocker (12") than the Ace. From the graph, I don't think I could find a 12" radius curve anywhere on the MK Pro.

Bill, when you have the time, could you do sliding window fits, as you did previously?  I'm curious whether you actually detect evidence in new blades to support Paramount's characterization of a compound radius (12" and 27") spin rocker on the Ace and a single radius (12") spin rocker on the Pro, even if the values differ from 12" and 27".  Also interested in variations in the main rocker radius along the length of the blade in new blades.

[Bill_S]

OK, I'll put it on the list.

I made rocker measurements in 1/4" increments along the blade's length to facilitate doing that.

[Query]

Just as a curiosity, with your rocker guage, if you do measurements off the left and right edges of the same blade, how similar are the rocker profiles?

Bill, as to your question as to why there is a base plate warp of close to 1/10" - I assume it is because of what I mentioned before - that the manufacturers say that bottoms of most base plates are deliberately made warped, because most boot bottoms are warped. And vice-versa. I.E., past history, rather than an attempt at a new optimal design. When I mentioned Sid Broadbent claim that mounting would be easier if baseplates and boot bottoms were be fully CoPlanar, the people I talked to at boot and blade companies agreed, in theory - but they still kept doing it the way it had been done before, because that was what was expected.

[tstop4me]

I was at a pro shop today.  I looked at the sample Coronation Ace and MK Pro on display [only one blade each, not a pair].  On visual inspection, the sole plate on the Pro was as flat as the one on the Ace.  Perhaps the cupped or dished sole plates on your Pros are indicative of manufacturing variation (or defect).

I'm beginning to suspect the curvature of the sole plate is a matter of manufacturing variation (perhaps induced during brazing?).  I was back at the pro shop.  This time I brought a steel machinist's ruler with me.  I did a quick check of three Wilson blades (Coronation Ace, Gold Seal, Pattern 99) and two MK blades (Professional and Gold Star).  They all showed some degrees of curvature longitudinally (toe to heel), transversely (inside edge to outside edge), or both.  Specifically for CA vs Pro, longitudinal curvature was more pronounced for CA than for Pro, but transverse curvature was more pronounced for Pro than for CA (this is upon simple visual inspection against the straight edge; no measurements).  Even the solid Gold Seal sole plate had some visible curvature.

I have 4 pairs (8 blades) of used Coronation Ace stashed away; late 1970's to 2014 vintage.  The sole plates on two blades were nominally flat longitudinally and transversely; the sole plates on the other blades had some degree of curvature either longitudinally, transversely, or both.  The sole plates on my old Eclipse Aurora had more pronounced curvature both longitudinally and transversely than on any of the CA's.

[Bill_S]

Good to know. Thanks for reporting on this. It appears that the amount of mounting plate curvature varies quite a bit, especially between manufacturers.

[Bill_S]

Rocker Radii Sliding Window Calculations

To calculate a rocker radius, you need to have measured coordinates for three points along the curve. I employed the data found for the rockers previously used for plotting curves. With those numbers already in hand, I used an online calculator from http://www.ambrsoft.com/trigocalc/circle3d.htm to do the number crunching to find radii.

Using a series of three measurements at various places along the blade, you achieve a "sliding window" measurement that shows how the rocker changes from tip to toe. The trouble with doing this is that precision decreases with smaller "windows" along the blade. Long radii, such as the main rocker, are especially prone to a lack of precision. One answer is to spread out the three measured points instead of having them crowded together. A better precision measuring device would also help.

At any rate, here are some graphics that I put together after doing the calculations from earlier measurements.

The Coronation Ace blade...



The MK Professional blade...



I indicated the "window" size using the width of the translucent color blocks, with the calculated radius immediately above them. Some overlapping exists, so I thought that translucent tints would allow the viewer to see the distances used. Most "windows" have the third middle point equi-distant from the ends, except for the tail of the blade where I ran out of room.

Vertical height of the colored blocks doesn't signify anything. It was merely a way to give the jumble of numbers some space from each other.

I've also indicated the non-skating zone for each of the blades. When a blades is pressed forward until the lowest pick touches, there is some distance along the curved blade that doesn't touch. Even though I've included some radii for the blades in this non-skating zone, it is essentially a useless number for actual skating. It never touches the ice. However the spin rocker will be immediately beyond it.

You can see that I calculated the rocker between 5" and 8" for both blades, and that spreads the points out enough that the number should be accurate. I used a smaller 2" sliding window for most of the calculations, so you will see a little scatter in the numbers there.

This is a long and complicated post, and most readers will just gloss over it. However I know that at least a couple of you are interested.

[Bill_S]

tstop asked...

I'm curious whether you actually detect evidence in new blades to support Paramount's characterization of a compound radius (12" and 27") spin rocker on the Ace and a single radius (12") spin rocker on the Pro, even if the values differ from 12" and 27".

It looks like the new Ace does have a compound spin rocker, but the spin rocker on the Pro will be about double the 12" value you cited.

It begs the question, which is better, a gentle rocker that doesn't change much with distance (MK Pro) or the compound rocker with a tight radii at one small point (Ace)?

[tstop4me]

* Gee, Bill, great combo of detailed analysis and clear presentation graphics.  Not sure how many here will appreciate what you've done; but I certainly do. 

* One surprising result is that, although the spin rocker profiles of the CA and Pro are substantially different, the heel lifts are nominally the same.  That means the heel lift does not correlate well with the spin rocker profile.  Looks like variations in the main rocker profile  (particularly the rounding near the tail?) disrupts any correlation.

* Your results on the CA do reasonably support Paramount's conclusion of a nominal compound spin rocker (close enough to a 12" radius behind the drag pick, followed by a 27" radius transition zone leading to the main rocker). 

* The biggest surprise of all is the spin rocker on the Pro.  Your results do reasonably support a nominal single radius spin rocker, but the smallest local radius is only ~21", not 12".  This will come as a major disappointment (and shock) to coaches who recommend the Pro over the CA specifically for spins, precisely because the Pro ostensibly has a rounder spin rocker.  What is not known, and what you can't answer, is what the manufacturing variation is.

If you bought the Pro specifically with the expectation of a rounder spin rocker than the CA, perhaps you should consider requesting an exchange (in case you got an extra flat sample)? 

[MCsAngel2]

This will come as a major disappointment (and shock) to coaches who recommend the Pro over the CA specifically for spins, precisely because the Pro ostensibly has a rounder spin rocker.  What is not known, and what you can't answer, is what the manufacturing variation is.

If you bought the Pro specifically with the expectation of a rounder spin rocker than the CA, perhaps you should consider requesting an exchange (in case you got an extra flat sample)?

In all the reading I've done since I've come back to skating, it's the CA that is known for having practically the roundest spin rocker on the market. CA for spins, Pro for jumps.

[tstop4me]

In all the reading I've done since I've come back to skating, it's the CA that is known for having practically the roundest spin rocker on the market. CA for spins, Pro for jumps.

All I can say is that's the opposite of what I've read and of what three coaches, including my own, have told me. 

[Bill_S]

This confusion doesn't surprise me. I've heard it both ways, and it's one of the reasons I'm taking such a close look at these two blades.