OK Tuners, Riddle Me This.....Hanging Burr

[Dakine]

I obsess over my tunes and pay a lot of attention to my skis after a session.
Something I have notice recently it a well tuned edge develops a hanging burr after a good carving session on icy snow.
From the mechanics of the interaction between ski and snow, I would expect the burr to be pushed out laterally caused by the sliding motion of the edge across the snow.
But no, the burr is pushed out vertically leading to a slight hanging burr that I can catch my fingernail on.
A couple of passes with a fine stone in a base guide removes the burr but I cannot see why it forms.
The hanging burr seems more pronounced in the forebody of the ski.
I'm an engineer and it bugs me that I don't understand the dynamics of how this happens.
Does anybody have a clue?

 

[Sibhusky]

Unless you're dragging your outward tip inwards to join the inner ski on every turn, I would not think this would happen even with blue ice. I would think you'd have to be hitting rock to cause that. Did this happen every single time or did it happen once?

Are you one of those chair lift ski clackers? I pretty much assume they don't tune their own skis when that stuff starts.

 

[Dakine]

Unless you're dragging your outward tip inwards to join the inner ski on every turn, I would not think this would happen even with blue ice. I would think you'd have to be hitting rock to cause that. Did this happen every single time or did it happen once?

Are you one of those chair lift ski clackers? I pretty much assume they don't tune their own skis when that stuff starts.

It happens every time I ski but I'm going to pay more attention.
I switch skis from foot to foot so I'm not sure which edge (inside or outside) it is happening to.
I'm obsessive about not banging or scissoring my skis, ever.

 

[Dakine]

I'll try and get a pic of what I am seeing.

 

[BClipped]

Once you remove it with the base stone does it re-appear after skiing again, or do you have to sharpen the edges and then go skiing to make the hanging burr return?

 

[Dakine]

Once I hone it down, it still comes back but not as much,
I don't have a macro lens but in this shot you can see how it shaved my fingernail.
It is a pretty small burr that doesn''t seem to affect the ski but it bugs me I can't explain it.

 

[CalG]

A square edge will pull a curl.

 

[Dakine]

No kidding?
It only shaves when I run my nail across the base from the center towards the edge, not when I run my nail across the edge from the top to the bottom.
It is a small hanging burr for sure.

 

[Doug Briggs]

I obsess over my tunes and pay a lot of attention to my skis after a session.
Something I have notice recently it a well tuned edge develops a hanging burr after a good carving session on icy snow.
From the mechanics of the interaction between ski and snow, I would expect the burr to be pushed out laterally caused by the sliding motion of the edge across the snow.
But no, the burr is pushed out vertically leading to a slight hanging burr that I can catch my fingernail on.
A couple of passes with a fine stone in a base guide removes the burr but I cannot see why it forms.
The hanging burr seems more pronounced in the forebody of the ski.
I'm an engineer and it bugs me that I don't understand the dynamics of how this happens.
Does anybody have a clue?

Do you keep a left and right ski? If so, inside or outside edge? Both?

 

[eok]

I think for us to come up with ideas that might explain why the burr happens, some more details are needed:

- Edge angles
- Ski models
- Edge tuning tools
- Snow type(s)

Without the above, my guess to explain what might contribute to the burring (especially in combination):

- Tuning to higher edge angles - especially for the side edge - perhaps could help make this happen. Eg: 0.5/4.0 or more extreme.
- Super precise rotary sharpening tools can produce a very precise fine edge finish, which might be more prone to burr with use.
- Super abrasive snow/ice can cause a surprising amount of wear to bases & edges. Especially if racing speeds are involved.
- The quality of steel used for the edges might be softer than assumed.

Other than that, I'm curious how the burring is happening too. I've never seen this on my skis.

 

[Dakine]

@Doug Briggs
Nope, put on my skis randomly most of the time....
Next time I ski I'll figure out which edge has the burr.
I have been working on much more two footed carving with rolling from the inside ski LTE to the inside ski BTE to initiate.

 

[Dakine]

@eok Tune to between 0.5 and 1 base and 3 side on everything.
Tune old school with a 3.3 degree file guide I made and lots of honing to 1200 grit at 3 degrees.
Lots of man made Midwest snow which is fast and abrasive.
No longer racing but ski over 40 a lot.
Nothing wrong with the edges on my Kastles, Blossoms and Fischers,but they file a bit harder than lesser skis.

 

[Doug Briggs]

Did you say what kind the problem skis are?

 

[Dakine]

Doug...Look one post up.
It seems to happen to all my skis except maybe the FX94"s.

 

[ScottB]

What you are getting is a bit weird. I sharpen and tune my skis often and have never experienced that. I did have hanging burrs on my skis before, but it was my tuning that created them and I didn't get rid of them before I used the skis. I felt them right away and a few strokes with a gummy stone and they were gone. Skiing always dulls my skis and they feel less sharp.

My guess would be they are left over from your tuning and get "more exposed" from skiing. I have stopped using my rougher diamond stones and only use the 600 grit and a silicon carbide stone to put an edge back on the ski. I find the 400-100 grits put more marks in the edge than are there before using them. I convinced myself the conventional wisdom of starting with a 200-400-600 polish is doing more harm than just a 600- carbide polish.

Last random thought, if your burrs are just small spots, is there dirt or "contamination" on your slopes that could be causing them. I only get burrs if I hit something, and if its a decent size rock, its more than a burr.

 

[Dakine]

@ScottB In the spots where the hanging burr is, the skis feel razor sharp, much more so than after they are honed.
But the sharp edge is hanging, not lateral like I would expect.
You may be on to something with small stones in the snow, I could see how that would push the edge in the right direction.
I have to thank all you guys for the thoughts.
What I am seeing is real and it is weird.
,,,,maybe aliens involved?

 

[CalG]

let gumi have a pass at those edges.

 

[eok]

The only other thing I can think of is that the gate/fence posts the resort uses in their lift corrals and loading areas. Some smaller/older resorts may still use some of the old posts made of steel. If you glance one of those posts at modest speed in the corral (easy to do when you come in hot on an uncrowded day) it can affect your side edge. Especially if the post is made of rectangular steel tube: the corner edges can get sharp after several seasons of abuse. Even worse if the posts have a projection in the bottom section - which is used to push the post into the snow initially (then the post is hammered into the snow the rest of the way). If those projections become exposed in the corral area they can add some extra "structure" to your bases.

 

[François Pugh]

The only other thing I can think of is that the gate/fence posts the resort uses in their lift corrals and loading areas. Some smaller/older resorts may still use some of the old posts made of steel. If you glance one of those posts at modest speed in the corral (easy to do when you come in hot on an uncrowded day) it can affect your side edge. Especially if the post is made of rectangular steel tube: the corner edges can get sharp after several seasons of abuse. Even worse if the posts have a projection in the bottom section - which is used to push the post into the snow initially (then the post is hammered into the snow the rest of the way). If those projections become exposed in the corral area they can add some extra "structure" to your bases.

This so far is the best hypothesis so far. A more far-fetched one is the heat treatment or other working of the metal in the edge has left it with an unsymmetrical tendency for any fine edge to curl down.

 

[oldschoolskier]

w

One thing I could suggest is the lift (chair) itself if it has foot rests.

The second is you have debris on the slopes as you are occasionally brushing against it with the edge as the photo looks like it only for short sections.