Correct Blade sharpening

[mnrjpf99]

Today I tried yet another pair of skates, in hopes of finding a good fit. The boots work good. Yay! However, the blades needed sharpening, so I had the rink skate shop do it. After they were done, I tried to skate and it was a nightmare! The blades are a lower end basic blade , so therefor they are narrow. Come to find out, after I gave up and came home, the blades were not sharpened square. I had a high outside edge on the left foot and a high inside edge on the inside edge on the right foot.

I am going to take them back and have them corrected on Friday. From now on, I will be sure to bring my own square, to check the blades after sharpening.

[Query]

I am going to take them back and have them corrected on Friday.

Don't let that shop touch your blades again!

Edge even-ness is one of the most obvious things to check, that your sharpener should have checked. On a scale where you couldn't skate, no one competent makes that mistake. Ever.

For a number of reasons, a shop staffed by idiots, or people ignorant of figure skates, will likely destroy your blade in a few sharpenings - or maybe in just one.

Of course, it is conceivable the head of the shop, or someone else in the shop, is much better than the others with figure skates, and that if you only use that person, you might be satisfied. Ask around.

[mnrjpf99]

The guy who sharpened them, just "eye balled" the edge, instead of using a square to check the blade. The blades that were sharpened are a crappy low end blade, but that's not the point. Imagine how many sets of good quality blades have been ruined by people like that?

They do have a guy that's more experienced with figure blades, but he was not in at the time. I may still have him fix the blades, to make a point. If they were a good quality blade, I would have been super P****d.

I was wondering about something Query? If you have a average width blade like a quality blade that is sharpened at a 1/2" ROH, would you have to sharpen a thinner blade at a 7/16" to get the same bite as the 1/2" on a regular width blade?

[Query]

If you have a average width blade like a quality blade that is sharpened at a 1/2" ROH, would you have to sharpen a thinner blade at a 7/16" to get the same bite as the 1/2" on a regular width blade?

Please don't view me as a super-expert! I mostly learn from making mistakes.

But yes! Basic geometry. There have been some posts on this forum, and elsewhere where people figured out the angles involved.

However, hockey blades are thinner than figure blades, yet I think the most common ROH's around where I live are 1/2" for hockey, 7/16" for figure. (There are no universal standards.)

And speed skates are thinner still (much, much thinner), yet have no hollow - they are sharpened flat.

(Part of the reason for those discrepencies is that figure skating judges, especially school figures judges, love artificially clean edges, with no skid, whereas hockey and speed skaters don't care how clean the edges are.)

And school figures skaters often used to use wider than normal figure blades, yet also used larger ROH's.

But in your defence, many ice dancers use "thinline" blades, which are thinner on the bottom, and they do sometimes use a slightly smaller ROH on average than other figure skaters.

It is hard to come universal conclusions about what ROH a given skater using a given blade will use.

Incidentally, some figure, hockey and speed skaters try to create "foil edges" on the sides (there are other names for such edges), extremely thin sheets of metal on the sides that extend into the ice, that makes edges very sharp regardless of ROH. The "Flat Bottom V" edges created by some Blackstone brand wheel dressers is somewhat similar. Both of these are extremely fragile, and need extra care.

[tstop4me]

For an ideal geometry, here are the values of bite angle as a function of blade thickness for ROH = 7/16" and ROH = 1/2".

T = Blade Thickness (inch)
BA1 = Bite Angle (deg) for ROH = 7/16"
BA2 = Bite Angle (deg) for ROH = 1/2"

T          BA1     BA2

0.100   06.56   05.74
0.101   06.63   05.80
0.102   06.69   05.85
0.103   06.76   05.91
0.104   06.83   05.97
0.105   06.89   06.03
0.106   06.96   06.08
0.107   07.02   06.14
0.108   07.09   06.20
0.109   07.16   06.26
0.110   07.22   06.32
0.111   07.29   06.37
0.112   07.35   06.43
0.113   07.42   06.49
0.114   07.49   06.55
0.115   07.55   06.60
0.116   07.62   06.66
0.117   07.68   06.72
0.118   07.75   06.78
0.119   07.82   06.83
0.120   07.88   06.89
0.121   07.95   06.95
0.122   08.01   07.01
0.123   08.08   07.07
0.124   08.15   07.12
0.125   08.21   07.18
0.126   08.28   07.24
0.127   08.35   07.30
0.128   08.41   07.35
0.129   08.48   07.41
0.130   08.54   07.47
0.131   08.61   07.53
0.132   08.68   07.59
0.133   08.74   07.64
0.134   08.81   07.70
0.135   08.88   07.76
0.136   08.94   07.82
0.137   09.01   07.87
0.138   09.07   07.93
0.139   09.14   07.99
0.140   09.21   08.05
0.141   09.27   08.11
0.142   09.34   08.16
0.143   09.41   08.22
0.144   09.47   08.28
0.145   09.54   08.34
0.146   09.61   08.40
0.147   09.67   08.45
0.148   09.74   08.51
0.149   09.80   08.57
0.150   09.87   08.63
0.151   09.94   08.68
0.152   10.00   08.74
0.153   10.07   08.80
0.154   10.14   08.86
0.155   10.20   08.92
0.156   10.27   08.97
0.157   10.34   09.03
0.158   10.40   09.09
0.159   10.47   09.15
0.160   10.54   09.21
0.161   10.60   09.26
0.162   10.67   09.32
0.163   10.74   09.38
0.164   10.80   09.44
0.165   10.87   09.50
0.166   10.94   09.56
0.167   11.00   09.61
0.168   11.07   09.67
0.169   11.14   09.73
0.170   11.20   09.79
0.171   11.27   09.85
0.172   11.34   09.90
0.173   11.40   09.96
0.174   11.47   10.02
0.175   11.54   10.08
0.176   11.60   10.14
0.177   11.67   10.20
0.178   11.74   10.25
0.179   11.80   10.31
0.180   11.87   10.37
0.181   11.94   10.43
0.182   12.01   10.49
0.183   12.07   10.54
0.184   12.14   10.60
0.185   12.21   10.66
0.186   12.27   10.72
0.187   12.34   10.78
0.188   12.41   10.84
0.189   12.47   10.89
0.190   12.54   10.95
0.191   12.61   11.01
0.192   12.68   11.07
0.193   12.74   11.13
0.194   12.81   11.19
0.195   12.88   11.24
0.196   12.94   11.30
0.197   13.01   11.36
0.198   13.08   11.42
0.199   13.15   11.48
0.200   13.21   11.54

[tstop4me]

Note that for a 0.150" thick blade, ROH = 1/2" yields a bite angle of 8.63 deg. 

If you have a much thinner blade, (e.g., 0.100" thick), and if you want to maintain the same bite angle, you need a much smaller ROH:

ROH = 5/16" yields a bite angle of 9.21 deg

ROH = 3/8" yields a bite angle of 7.66 deg

ROH = 7/16" yields a bite angle of 6.56 deg


To get exactly the same bite angle of 8.63 deg, you would need an ROH = 1/3".

[Query]

It may get complicated. It is possible that a thinner blade might cut into the ice more effectively, and thereby provide stronger resistance to lateral motion, so maybe you don't need the same bite angle with thinner blades.

A lot of this stuff is speculative.

[tstop4me]

It may get complicated. It is possible that a thinner blade might cut into the ice more effectively, and thereby provide stronger resistance to lateral motion, so maybe you don't need the same bite angle with thinner blades.

A lot of this stuff is speculative.

Agree that there are other variables to consider, and the bite angle is not necessarily determinative.  I was simply answering the OP's question on whether you need to vary the ROH for blades of different thicknesses to maintain the same bite angle. 

I don't ice dance.  But from various websites, ice dance blades seem to be thinner than freestyle blades, and the recommended ROH for ice dance blades is typically 5/16", which is typically not recommended for freestyle blades.

Also, real blade geometries are non-ideal.  In particular, skate sharpeners typically use a flat whetstone to hand-hone the exterior surfaces of the edges (away from the hollow) at a slight angle to the sides of the blades. 

[Query]

ABut from various websites, ice dance blades seem to be thinner than freestyle blades, and the recommended ROH for ice dance blades is typically 5/16", which is typically not recommended for freestyle blades.

There is no "typical", any more than there is a typical foot size. But the most common ice dance blade at the competitive level is MK Dance, which MK says does indeed come from the factory with 5/16" ROH. But Ultima says the Ultima Dance come with 7/16".

I think it is quite "typical" for skate techs to sharpen all figure skates, and maybe all hockey skates too, with one hollow, which they choose, unless asked otherwise, because that minimizes the time and costs to the skate tech. They can keep the same wheel mounted, and don't have to re-dress it as often. Even some very high end skate techs do that.

I sharpen both my Dance (Ultima Dance) and Freestyle (Ultima Supreme) blades with 3/8", because the Pro-FIler sharpening device wasn't available in 5/16" or 7/16" ROH. (It is now nominally available in 7/16" and 5/16" ROH - but the manufacturer said 7/16" was really shipped as 3/8". It seems to work fine, though I'm not an expert skater.

If I remember right, Mike Cunningham, a well known skate tech, told me that various figure skaters have requested him to sharpen everything from about 1/4" (fairly common, he said, in NY City) to about 3/4" - and maybe greater for school figures.

Honestly, I wouldn't worry about it too much. Find a skate tech that does things well, and consistently, and stay with him/her, or do your own. There are much more important things than the exact ROH, that affect effective sharpness more.