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Adventures of a wannabe tuner: flat filing bases

post #1 of 9
Thread Starter 

The other day I found a pair of 80's(?) vintage Fischers in someone's trash (they have "high molecular sintered racing base" and "twin cam" bindings!).  I thought -- hey! -- I can use these to practice tuning on.  (As I was tossing them into my car, the previous owner popped his head out the door and called to me, "Be careful when you use those things....the guy in the shop told me they're not safe to ski on any more!" roflmao.gif ).  As if!  Like, he-llo!

 

So, here they are, in all their rusty-edged glory.  No need to scrape the wax off before working on them....they look like they never got a coat of wax in their life!

 

DSCF5404.JPG

 

[Disclaimer: Duh....this is sort of a diary of my experiments, done for my edification and amusement, certainly not an instructional manual.  Although there may be educational tidbits scattered throughout, it goes without saying that no innocent soul should blindly copy anything I do, especially on a "real" pair of skis!!! eek.gif ]

 

That said, I checked them with my true bar, and found pronounced concavity at the shovel....

 

DSCF5430.JPG

 

getting progressively less toward the binding, and becoming essentially flat from the binding to the tail.

 

DSCF5428.JPG

 

Ok, this looked like a good candidate for my new panzer file.  After taking a few strokes with just the file in my hands, it seemed to me like the file was bending, despite my trying to put pressure in the middle with my thumbs.  So to eliminate that, I screwed the file to a piece of wood to keep it flat.  (Of course, there's no guarantee the wood is really flat either.  That's something I should check before using this "for real".)

 

DSCF5408.JPG

 

I quickly found out is that the cutting edge is the convex side of the curved teeth, not the concave side.  The following picture shows the direction I had to hold it when pulling towards me.

 

DSCF5410.JPG

 

And, unlike a regular file, you must always hold it diagonally, not at right angles across the ski, otherwise the teeth can make gouges in the base.  This makes it tricky to use near the shovel.  If you hold it diagonally over the area where the shovel starts, you can make horrible gouges!  (Guess how I found that out?  Can you say, "I'm so glad I didn't try this on a good pair of skis" three times fast?  Sure you can.)

 

Yet, you can't hold the panzer file at right angles like you would a regular file in this region either.  So I just left that area alone, planning to return to it when I did the finish filing with a mill file.  I think if I ever do this on my real skis, I would put a piece of masking tape where the shovel starts to turn up, as a warning to keep the file away from there.

 

DSCF5414.JPG

 

After a while I got the hang of it and got the base reasonably flat.  The panzer file is very sharp and really does cut very fast, almost like a knife through butter, terrific for this sort of application.  One thing I noticed when checking with the true bar is that I must have been bearing down harder with my right hand, since I was cutting more deeply on that side.  So I took some strokes the other way, from tail to tip, and that evened it out.

 

Like the shovel, the tail area where the ski turns up was another region in danger of gouging.  Lesson: stop before the tail and handle it with a mill file at right angles.

 

DSCF5416.JPG

 

Finally, I used my mill file to finish the job, holding it at right angles near the shovel and tail, and diagonally in between.  I found it is quite easy to bend what appears to be a very stiff file, causing unintentional bevels.  I really had to concentrate on pressing strongly with my thumbs in the middle,  and just pulling (not pressing) with my hands on the overhanging ends of the file.

 

Another thing I learned is to keep cleaning the file and ski while filing, since I did manage to rub quite a bit of rust and dirt into the base in such a way that it wouldn't easily come off.

 

DSCF5417.JPG

 

The end result?  Still a bit of concavity at the shovel, but much better....

 

DSCF5424.JPG

 

....and flat everywhere else wink.gif

 

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I still have one sacrificial ski to go, so I'll see if I can do a perfect job on that one before (if ever) victimizing my real skis eek.gif

 

 

 

 

 

 

 

 


Edited by renenkel - 2/20/12 at 3:53pm
post #2 of 9

 

Quote:

"high molecular sintered racing base" and "twin cam" bindings!

 

They probably say "ultra high molecular weight sintered racing base." Which means they're pretty much the same base material used on good-quality skis today. Only significant difference (I think), is that on those old skis the base material is all clear / non-graphite impregnated.

 

"Twin cam" = a Marker trademark. I'm fairly certain they still use it, and that the bindings really still use a similar twin-cam design. That is: you can walk into a shop and buy "twin cam" binding today.

 

From seeing just part of the bases, it's pretty tough to judge the vintage of the skis. They could be '90s. They look too straight to make it likely they're newer than late '90s.

 

The "shop said they're unsafe" comment probably just means the bindings are no longer on the indemnified list. That wouldn't necessarily make them unsafe. Of course, the straight sidecut alone makes the skis pretty worthless. Not that I don't see people skiing on skis of that vintage fairly regularly....

 

We used to flat file skis (though never, in my experience, with a panzer file) to sharpen them in the old days, though those days are even older than those skis. As you no doubt know, the usual method to flatten a ski base is to stone grind it on a big monster machine that only skis shops have, which structure the bases. There are hand tools made specifically for the purpose (e.g. the base tool made by Ski Visions), but I think they're mostly used by our nordic-ski cousins.

 

Edited to add:

 

Actually, I think the groove makes it likely those are pre'90s.

 


Edited by sjjohnston - 2/20/12 at 5:09pm
post #3 of 9

NO file should be used at a right angle to the edge. They should all always be angled.

post #4 of 9
Thread Starter 
Quote:

Originally Posted by sjjohnston View Post

They probably say "ultra high molecular weight sintered racing base."

 

That may have been what they meant, but it didn't quite make it on to the lettering its entirety smile.gif

 

DSCF5433.JPG

 

No sacrilege to older skis intended eek.gif but they were going to end up in a landfill somewhere, so if they manage to teach me something about tuning, at least they will go to their eternal rest having contributed something to the world.  That said, after I've tuned the heck out of them, I'm thinking of cutting a off a foot or so off the shovel end and bolting them on to a pair of old ski boots to make me some snow skates!  biggrin.gif

post #5 of 9
Thread Starter 
Quote:
Originally Posted by Atomicman View PostNO file should be used at a right angle to the edge. They should all always be angled.

What do you do near the shovel and tail where the ski turns upward?  You can't use a file angled there, because then the center part will dig into the middle of the base.  I'm just wondering if you can use a normal file (not panzer) just on that part at right angles, and then turn it diagonal for the rest of the base?
 

 

post #6 of 9

I guess the graphic designers over-ruled the engineers, which isn't how it's usually done in German-speaking countries.

 

Just as a matter of pure history, that looks vintage last-few-years-of-the-'80s, I think. There are some experts in Marker history around here who could probably place the binding more precisely. The heelpieces seems to have vanished: it was presumably a relatively classic version of the Rotomat (aka "Explodomat").

post #7 of 9

Props for deciding to learn to perform basic maintenance on your own gear.  Good idea getting some test material to play around with.  I would recommend adding some safe bindings to also try skiing on your work in progress. 

 

Couple of things:

 

  • A panzer file has never been any part of my tuning supplies.  I'd actually use a belt sander to quickly flatten excess base before taking that monster to any of my bases.  My preferred method is several passes with simple large mill bastard periodically cleaning the teeth with a file card.
  • I have no idea what you mean by angling the file and having it dig in to the center of the bases near the tip and tail.  Flat is flat regardless of under the boot or on the rise of the tips or tails.
  • Those old school skis probably would ski better with a slight detune (dulling) of the tips and tails about <5 cm of contact to the ends,  DO NOT DO THIS WITH MODERN SKIS unless you are really sure you know what you want there i.e. bump skis or park skis.

 

 

Have fun and don't cut yourself!

 

 

post #8 of 9
Thread Starter 
Quote:
Originally Posted by crgildart View Post
  • I have no idea what you mean by angling the file and having it dig in to the center of the bases near the tip and tail.  Flat is flat regardless of under the boot or on the rise of the tips or tails.


Sorry if I was confusing in my attempted explanation.  What I mean is that, if you lay a file across the ski in an area where the base is flat such as under the bindings (not curved in the head to tail direction, as at the shovel or tail area) the file will contact the whole width of the base, regardless of whether you hold the file at right angles to the ski or diagonally.  Hence you would normally hold the file diagonally since it cuts best that way.

 

However, if you hold the file diagonally at the shovel, it is not possible for the file to contact the base evenly, because the file is flat and the shovel is curved.  The only way the file can properly contact the whole width of the curved part of the base is if it is held at right angles to the ski (because the ski is only curved in the tip-to-tail direction, and not in the side-to-side direction).

 

So what I was suggesting is, it seems to me that the only way you can properly file the base in the area where the ski starts to turn up (that is, at the start of the shovel or tail) is to lay the file at right angles to the length of the ski, and not diagonally across it.

 

post #9 of 9


I use a 6 in. very fine 18-22 TPC for base beveling. I have never had a problem and past the contact point is immaterial anyway.

 

From Racewax.com

 

NOTE 1: Files are made to cut while being held at angles between 45 & 60 degrees. Find the angle that works best for your file. Use a sharp and straight file; dull or bent files won't cut smoothly, will require more pressure and skew the bevel.

Quote:
Originally Posted by renenkel View Post

What do you do near the shovel and tail where the ski turns upward?  You can't use a file angled there, because then the center part will dig into the middle of the base.  I'm just wondering if you can use a normal file (not panzer) just on that part at right angles, and then turn it diagonal for the rest of the base?
 

 



 

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