Skis unskiable after stone-ground, structure bad? Now fine again - help us understand what happened.

[Doctor D]

From my structure theory page:

On cold crystalline snow, the ski base should be as smooth as possible so the points of friction are minimized.


On amorphous, wet snow, a coarser structured ski base is better to minimize the points of friction. Pockets of air between the ski base and the snow means that water is repelled from the ski base reducing the breaking effect.

[Alpinord]

Nice graphics and info Dr. D.

Correct me if I'm wrong, but as a general comment regarding 'unskiable' flat base bevels, I can't imagine that a ski would be absolutely 'unskiable' (or 90° corner). More difficult, but not impossible. I'd suspect something else first (like a burr).

[viking kaj]

Originally Posted by Atomicman

Hanging Burr It Was!

Isn't this why you are supposed to do a quick run with a gummi down the side of the edge after you have ground or filed the edges to the right angle to take the burr (hanging or otherwise) off? I know some people also run the gummi at an angle to the edge at the tips and tails to detune these slightly. Just curious.

[NE1]

Originally Posted by Alpinord

Nice graphics and info Dr. D.

Correct me if I'm wrong, but as a general comment regarding 'unskiable' flat base bevels, I can't imagine that a ski would be absolutely 'unskiable' (or 90° corner). More difficult, but not impossible. I'd suspect something else first (like a burr).

Right - we all used to ski 0/0 bevel not too many years ago (well maybe a few more than that ). Granted, we were not on supershaped skis, but it should not be unskiable - just a bit unforgiving.

[Atomicman]

Originally Posted by viking kaj

Isn't this why you are supposed to do a quick run with a gummi down the side of the edge after you have ground or filed the edges to the right angle to take the burr (hanging or otherwise) off? I know some people also run the gummi at an angle to the edge at the tips and tails to detune these slightly. Just curious.

A burr on your side edge will just break off when your ski is tipped on edge. Since most folks generally bevel their base edge first, a side edge burr is rarely if ever present.

A hanging burr goes down the side edge past the base edge down into the snow. You must use a very coarse grit stone flat against the base edge to knock the hanging burr off.


In regard to 90 degree (0/0) tuning.

To say this would be demanding is a gross understatement!!!!!!! Particularly on shaped skis in comparison to the old straight ski whihc was common place.
But the skiing style in the old days and the much less radical shape made sense wiath a 0/0 since most folks skied on edge or off and check turns and hocky stop style turns were the rule not the exception.


A 0/0 on very icy or very damp snow would make a shape ski virtually unskiable. it provides no ability to progressively increase or progressively engage edge angles and provides absolutly no slipping/skidding abilty whatsoever.

I just returned from a week in Sun Valley on man made snow with a .7 base edge bevel on my B5 Metrons and also recently skied here in Washington on a fresh .5 base bevel on my Stockli Laser SL in a 166cm.

The B5's were somewhat grabby on the man made. Not unskiable but very, very exacting. In the morning the snow was refrozen groomed slush and the surface was very uneven, contained ball bearings as well as holes, chunks and death cookies!

As I skied on them i did get accustomed to the .7 and also some of the x-tra sharpness was reduced to where the skis were very predictable and enjoyabel, although at first they were very instense on certian patches of snow on the hill.

the .5 on the Stockli's was way too demanding. Very, very harsh,. On edge or off, period!

I cannot imagine skiing either of these skis with any success with a 0/0 bevel setup unless you are on purely hero packed powder,.


As you can imagine there is absolutley 0% chance that either of my skis had any kind of burr on the edge.

I guarantee it! just like George Zimmer!

[Cgrandy]

How could a tech hand re-bevel an edge from .5 to 1 degree and not notice a burr the length of the ski.

How could the ski be hand waxed and scraped without this same notice. Wouldn't such a burr catch on the scraper?

Perhaps the burr was formed later. Not during the tune?

Perhaps I am a bit tactile, but the FIRST contact I make when tunning is to pass my thumb and fore finger in a very loose "grasp" down the length of the two edges. Feeling for nicks and burrs and all that's bad about metal edges.

"Great way to get a nasty metal sliver! Ask me how I know ;-)

Different awareness for different folks I suppose.

Good that the problem is known and gone!

CalG

[Atomicman]

Originally Posted by Cgrandy

How could a tech hand re-bevel an edge from .5 to 1 degree and not notice a burr the length of the ski.

How could the ski be hand waxed and scraped without this same notice. Wouldn't such a burr catch on the scraper?

Perhaps the burr was formed later. Not during the tune?

Perhaps I am a bit tactile, but the FIRST contact I make when tunning is to pass my thumb and fore finger in a very loose "grasp" down the length of the two edges. Feeling for nicks and burrs and all that's bad about metal edges.

"Great way to get a nasty metal sliver! Ask me how I know ;-)Different awareness for different folks I suppose.

Good that the problem is known and gone!

CalG

No, you would not notice a burr the length of the ski when hand tuning from .5 to 1 dgree. A hanging burr is not visible damge caused by skiing. A hanging burr on the base edge caused when setting the side edge bevel or polishing the side edge is microscopic. Since the base edge is beveled, no a scraper would never come in contact with it and again it is a microscopic curl formed on side edge that minutely sticks out past the base edge that causes absolute havoc with the interface of your edge to the snow.

Most folk would just get the file out and begin the process of increasing the base bevel. Once the base bevel was reset, the side edge bevel would also need to be reset, and a new hanging burr would be created at that time.

Anytime you file or diamond stone your side edge, you must deburr the base edge!

A 1 degree base bevel = 1mm of gap at 60mm across the ski. (Now you can see why your scraper idea is out the window).

Also, this happens all the time. Either techs are not aware of the necessity of this final tuning step, or are too busy and in a hurry to bother with it.

[SkiMangoJazz]

Atomicman, when we had this problem the tech ran it through the machine to get more base bevel and the problem persisted. I can't say for sure that he didn't then do the side edge again, but I was standing outside the shop and he did it very quickly - on a machine.

Would these machines automatically redo the side edge after increasing the base bevel?

[roundturns]

A- Man called it for me a couple of years ago with the hanging burr. He was absolutely dead on correct. Its just astonsishing to me the guys doing the tunes, don't realize they have to finish by hand( all of 1 minute) to be sure they don't leave a burr. A burr has an unbelievable effect on the ability to control your skis. It will make an expert feel absolute terror on the bunny slope. Yet it happens all the time, even at good shops.

[Atomicman]

Depends on the machine used I suppose. there are machines that do both, i believe.

The Automated Wintersteiger machine that the shop use wher I get stonegrinds done has an automated side edge beveler that you run the ski through by hand that puts a ceramic disc finish on the side edge as an add on machine that is also a Wintersteiger.

He may not have redone the side edge, but the symptoms you described are exactly what happens with a hanging burr.

I have never had a ski act strange due to a grind pattern, although the grind we used last week was an aggressive diagonal spring grind. (Worked great actually)

I just skied in sun ValLey on a extremely aggresive stone grind pattern and so did my son. I knocked the grind down with fiber-tex, hot scraped with Dominator Graphite base renew, hot waxed and then cool scraped and Roto-Brushed with Dominator Graphite Base Renew and then hot waxed and cool scraped and Roto-Brushed with old snow Race Zoom.

At .7 I knew on man made snow , my skis would be a little intense. but the grind had no effect other then letting me not get suctioned to the snow in the late afternoon low altitude slush!

[Atomicman]

Originally Posted by roundturns

A- Man called it for me a couple of years ago with the hanging burr. He was absolutely dead on correct. Its just astonsishing to me the guys doing the tunes, don't realize they have to finish by hand( all of 1 minute) to be sure they don't leave a burr. A burr has an unbelievable effect on the ability to control your skis. It will make an expert feel absolute terror on the bunny slope. Yet it happens all the time, even at good shops.

This is exactly what motivated me to learn to tune myself. I got sick & tired of the shops turning my top notch skis into useless conglomerations laminated materials!

for many years, i had no idea why the skis were skiing so weird. When i first began tuning, I had the same problem. i thought it was due to the concave bases on many Atomics and that could ahve been a contributing factor.

I was at a race in park city utah with my older boy in the tuning room with a baotload of 15- 20 year olds all tuning & waxing. one of the kids i knew well was running a stone down his base edge freehand and I asked himewhat the heck he was doing.

A LIGHT BULB WHEN ON, WHEN HE SAID, I DON'T KNOW, MY COACH JUST SAID TO DO THIS AS A LAST STEP!!!!!!

EVER SINCE, NO MORE FREAKY SKIING SKIS!!!! THAT WAS ABOUT 2002!

[hrstrat57]

After some thought here is my opinion based on posts and photos/graphics of structure posted here.....thanks alpinord, doctor d...

I ran my finger along all edges as I always do before skiing. Detected no burrs.

Skis grabbed, wobbled and were generally unskiable. SMJ brought back to shop, shop measured base bevel as nearly flat, ground a base bevel into skis iaw factory spec and returned them to us.

Different, not as grabby, but still unskiable. Now would not hold an edge on frozen granular.

Shop hand tuned, returned skis again, now ski very similar to SMJ brand new skis, same length model.

As I prepped my 170 RX 8's for summer storage I viewed the structure on both bases(170's still have factory tune, never ground) and bases on both are now nearly identical. Viewing the photos kindly provided by alpinord, the structure on the 175's previous to hand tune looked like a warm snow grind.

Thus I believe the problem was a combination of near flat base bevel and grossly improper structure for the conditions.

As a result of this troubling experience, I will never have a ski ground again.....I will always ski factory tune. Any ski becomes base damaged, edges rounded or otherwise requiring anything more that my diligent waxing and deburring?

It will go on ebay.

Now I have a continuing excuse for always having new skis

_________________________________

I remain curious(tho will never know the answer of course) as to how many skiers of limited experience and skills are rendered unlikely to get any better because of poor or inappropriate tunes?

Something I have never considered before, but as a nearly 10 year veteran ski pro should have. How many students did I miss the MA on blaming stance and balance flaws for poor technique when equipment should have been checked and considered as a factor? I could barely make a level 6 turn on these skis tuned the way they were. Luckily for me I was wise enough and had enough skill and experience to know the difference. How many others cannot identify equipment as the source of the problem in their skiing? How many skiers are as blessed as most of us are to nearly always be on new or hand tuned high end gear?

When I start to teach skiing again( which I plan to do once I retire from day job) it will be something I intend to learn more about.

Something to think about and discuss?

Thanks everyone!

[viking kaj]

Originally Posted by Atomicman

Anytime you file or diamond stone your side edge, you must deburr the base edge!

Also, this happens all the time. Either techs are not aware of the necessity of this final tuning step, or are too busy and in a hurry to bother with it.

My point exactly, a careful pass with the stone takes care of this. I could easily see it being residual to a stone grind/base bevel reset if the tech is a little sloppy.

[viking kaj]

Originally Posted by hrstrat57

As a result of this troubling experience, I will never have a ski ground again.....I will always ski factory tune. Any ski becomes base damaged, edges rounded or otherwise requiring anything more that my diligent waxing and deburring?

It will go on ebay.

Now I have a continuing excuse for always having new skis

Wow, that is a really amazing approach to tuning. You may want to consider a light stone/file job on your edges from time to time as well.

Just as a matter of curiousity, how often do others have their bases ground? I am lucky if I get in 10 days a year on any one of the skis in my quiver (there are 8) so I don't find myself doing this very often. Maybe every third year or so, but I could see myself selling the ski first as well.

[Atomicman]

Originally Posted by viking kaj

Wow, that is a really amazing approach to tuning. You may want to consider a light stone/file job on your edges from time to time as well.

Just as a matter of curiousity, how often do others have their bases ground? I am lucky if I get in 10 days a year on any one of the skis in my quiver (there are 8) so I don't find myself doing this very often. Maybe every third year or so, but I could see myself selling the ski first as well.

exactly! About once after 2 seasons unless some really obscene damage occurs (so far lucky) or i want to reduce the base bevel.

[Atomicman]

Originally Posted by viking kaj

My point exactly, a careful pass with the stone takes care of this. I could easily see it being residual to a stone grind/base bevel reset if the tech is a little sloppy.

I was just commenting on "the side of the edge" to clarify it is flat against the base edge to fix a hanging burr.

[viking kaj]

Originally Posted by Atomicman

I was just commenting on "the side of the edge" to clarify it is flat against the base edge to fix a hanging burr.

Yes, thank you for your informative post. I've got this now, will be careful to pass stone over both base and side edges at appropriate angle. I'm pretty sure that I do this anyway, but after this thread I will be sure to do so in the future.

[Lostboy]

Originally Posted by hrstrat57

...
As a result of this troubling experience, I will never have a ski ground again.....I will always ski factory tune. Any ski becomes base damaged, edges rounded or otherwise requiring anything more that my diligent waxing and deburring?

It will go on ebay.

Now I have a continuing excuse for always having new skis

Precision Tuning in Framingham and Danvers MA and the Race Place in Bend, Oregon are two specialty tuning shops with programs where you can ship your skis to them for a stone grind and tune and they will express mail them back to you. There are other top notch tuning shops that will do the same but those two come quickly to mind. Or, a pretty good bet would be to take your skis to any race oriented shop that does specialty tuning. Such shops don't just tune race skis but the nature of their racing clientele usually dictates that they have competent tuners.

I have a favorite local retail ski shop but would never send my skis there to be stoneground or the edge bevels set, having done so once.

[Alpinord]

Sounds a bit subjective, like one person's 'unforgiving' or 'less optimal' is another's 'unskiable' and somewhat dependent on the the ski type or 'performance level' and conditions. I have never experienced this, nor have I ever felt the need to get a base grind as dealing with them myself has kept them all 'very skiable' over the eons. This has been an enlightening thread.

The only time I can recall having troubles on a ski was in the late 70s/early 80s on a pair of Atomic slalom (black & yellow) skis where they had a very small sweet spot and were clearly different to get used and 'unforgiving' compared to my K2 710s, Dynastar Omeglass IIs & Rossi SMs at the time or anything before or since.

Now, I'm wondering if a different tune at the time would have changed my luck on those antique Atomics and I won't have sold them???

[Alpinord]

Forgot to post this link for anyone interested:

An Observation regarding base grinding.

[Cgrandy]

Boy This is great news! Now I have a real excuse for why I ski so poorly.

"there's a microscopic bit of metal hanging off these edges, You can't see or feel it, but it makes these sticks unskiable."

I like it!
Way better than just saying .
"Yes, I suck!"

All in jest! Please.

But I am going to look closely at the edges with a loop before and after every tune.

ahh but next year... the sun is out and sunday's pleasure is becoming a wonderful memory as steady streams of melt course off the eaves and down the roadways.

[Atomicman]

You can't see it but you can feel it You must feel it correctly by pulling the back of your fingers or thumb or a fingernail nail from base to edge on the base of the ski.


Check this out!

http://www.holmenkol.us/myadmin/data...ge%20micro.pdf

and this!

http://www.holmenkol.us/myadmin/data...20Work%204.pdf

[Cgrandy]

A-man

It would be much better for me if I could leave the imperceptability description intact.
To harm Saint- Exupery
"What is essential is invisible to the eye.
One sees rightly only with the heart"
;-)

[atasic]

So, how do you detect hanging burr and what is the technique and preffered tool to take care of it and still have a sharp edge.
Thanks

[Alpinord]

I just run an Arkansas stone flat along the base edge.

[Atomicman]

Originally Posted by atasic

So, how do you detect hanging burr and what is the technique and preffered tool to take care of it and still have a sharp edge.
Thanks

Alpinord nailed it, but did you not read the two articles I posted above??????

http://www.holmenkol.us/myadmin/data...20Work%204.pdf Last paragraph of 1st page!!!!!!

[2-turn]

Originally Posted by Atomicman

I have never had a ski act strange due to a grind pattern, although the grind we used last week was an aggressive diagonal spring grind. (Worked great actually)

I've seen it and felt it. What happens is some shops stone grind, then use the belt sander to take the stone pattern out of the base edge. Then sets the bevel with the side edger. If they don't get the pattern out of the base edge, the ski is squirelly similar to a hanging burr, but not nearlybas predictable. Really wierd.

[Atomicman]

Originally Posted by 2-turn

I've seen it and felt it. What happens is some shops stone grind, then use the belt sander to take the stone pattern out of the base edge. Then sets the bevel with the side edger. If they don't get the pattern out of the base edge, the ski is squirelly similar to a hanging burr, but not nearlybas predictable. Really wierd.

Where in this process was the base bevel set. That should take the grind pattern out.

Is this if ythe base bevel is set by machine at the time the base is ground?

I have never had my skis base beveled by machine. Only stone ground and then either hand tuned by the shop or by me and only by me for the last 5 years.

Most skis that are being stoneground already have base bevel when the stongrinding takes place. this means the edges are below the base. I have not seen the pattern in any of my skis on the base edge.

[Voltron]

I've seen this before...

Originally Posted by John Todd of Wintersteiger

One of the things we see going into shops and looking at their done rack is skis/boards with structure in the edge. Looking closely at the metal edge you may see marks left from the stone, that same structure that makes the base glide so well doesn’t work in the edge. Having structure in the edge is normal during tuning, you are trying to get the base flat and you will remove some edge material with the stone which leaves the marks. But the edges need to be beveled and polished after being run across the stone which removes the structure from the edge. If this is not done correctly not all the structure gets removed and there are problems. The ski/board will run like it is on rails, not wanting to turn at all. The customer will have the same complaints as if the base were concave or the edges not beveled at all, but if you check it with your true bar the base will look fine. After making your finish pass on the stone check the edges carefully for structure. Run them across a Tuning belt, Finishing belt, or better yet a Ceramic Disc machine to remove any trace of the structure in the edge and this should also produce a nice bevel in the base edge.

Original Thread

[Atomicman]

Originally Posted by Voltron

I've seen this before...







Original Thread

Nice quote!! good job Voltron, there ya go! Sounds like exactly the culprit in HR & SMJ's issue.