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DIY base edge bevel fix on Karhu Guides

Discussion in 'Backcountry' started by Ziggy, May 1, 2020.

  1. Ziggy

    Ziggy A Local Ski Pass: Gold

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    A number of Karhu Guides sent to Australia have a base edge bevel along the pattern that's about 10-15 degrees, making edge holding on ice or hardpack very ordinary.

    First I thought this was a poor grinding job at the factory but now it looks more like a manufacturing cock-up that was compensated for by overdoing the bevel angle.

    I got a ski shop to regrind the edges of my first pair, with the loss of some fish scales. My new old pair I've done myself as an iso project.

    I first tried a Swix adjustable-angle file guide that had worked fine along the smooth base section at an angle of two degrees. Alongside the pattern it needed to be set to 5 degrees, needed the file holding to be modified to avoid grooving the pattern and tended to press swarf into the base.

    So I went back to the old hand file method with wraps of tape around the hilt to tilt the file and produce the angle. The tape tended to tear so the next step was to use some U-section rubber gasket from Clark Rubber to lift the handle end.

    The tools:



    Both files are called bastard. The stubby one in the Swix guide is a single cut and the hand file is a 20cm double cut (with two sets of teeth crossing each other). Single cuts more cleanly. Use Bahco or Nicholson; cheap files make for a cheap result.

    On the hand file and to the left of it is the 3mm thick (per wall) rubber gasket. It just slipped over the file.

    At the bottom is a file brush for cleaning wax and swarf from the file teeth. A toothbrush works too. Top right is a cabinet scraper for cleaning up blemishes in the base.

    In the pic above the lower edge has been filed and the upper is ready to go.


    You can see green marks on the ski, on some fish scale tips and at a few points along the edge. These are made with water soluble felt-tip pen and they show what result the file is producing.



    It's a simple matter of repeatedly pushing the file along a section of the ski with a light touch. It should be lifted back, not dragged, and the swarf brushed off regularly.

    When the gasket was sliding along a side that'd been done it tended to drag and tear and that was fixed by a turn of duct tape around it.

    Some hard wax rubbed into that section of the pattern helped make for a smooth action.

    While this gasket is quite thick at 3mm per wall, skewing the file reduces its tilt and cuts better.

    Watching what happens to the green inked edge tells you if you need a steeper or shallower bevel angle out of the file. Decrease the skewing of the file for steeper; increase it for shallower (within limits).



    The ski was laid on three 'bridges' to maintain its camber.



    The fish scales lost a bit of height generally to 10mm from the edge and at one point up to 20mm.

    The bevel angle produced is about 5 degrees. It can be reduced only at the cost of more fish scales.

    To clean out pressed-in swarf from the base you can use a brass brush or non-scratch scourer.

    It's possible once the desired angle is produced to use a finer file for a cleaner result.

    I've yet to decide whether to hone the vertical edge. Doing that would produce a finer and so longer-lasting corner.
     
    GS, skifree, BoofHead and 1 other person like this.
  2. Fozzie Bear

    Fozzie Bear One of Us Ski Pass: Gold

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    10-15 deg is huge. I have a chart for every ski I have owned and the base is between 0.2 and 1.5 and the edge between 1.5 and 3
     
  3. skifree

    skifree A disciple of the blessed avi giraffe Moderator Ski Pass: Gold

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    How old is a Karhu Guide now as a ski? Out of production since?
     
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  4. teckel

    teckel Pool Room Ski Pass: Gold

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    Karhu was bought by K2 who also own Madshus, and the same ski is now called the Madshus Annum.
    Other brands owned by K2 include Marker, Volkl, Full Tilt, Line, Ride and Dalbello. Also Atlas and Tubbs snowshoes
     
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  5. skifree

    skifree A disciple of the blessed avi giraffe Moderator Ski Pass: Gold

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    That’s an answer to a different question.
     
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  6. Chaeron

    Chaeron OutLiar Ski Pass: Gold

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    The Karhu brand existed between 1978 and 2010. K2 bought Madshus in 1988 and bought and then retired Karhu in 2010. Kohlberg PE bought the combined unit (K2) in 2017.

    The transition from Karhu Guide to Madshus Annum took place in 2010.

    https://www.telemarkskier.com/legendary-ski-maker-karhu-telemark/
     
  7. Ziggy

    Ziggy A Local Ski Pass: Gold

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    Dostie said they were made by Madshus.
     
  8. Chaeron

    Chaeron OutLiar Ski Pass: Gold

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    K2 now in US private equity hands since 2017 - the Kohlberg Wintersport stable includes K2, Volkl, Marker, Dalbello, Madshus, Line, Ride, Full Tilt, BCA, Atlas, and Tubb.....

    Company headcount has been cut by two thirds - so lots of rationalisation, and outsourcing...

    Kohlberg and Company now has 17 percent of alpine boots market share with Dalbello, Full Tilt, and K2 alpine boots; 36 percent of the alpine ski market share with K2, Volkl and Line skis; and 12 percent of the snowboard market share with K2 snowboards and Ride.
     
    #8 Chaeron, May 1, 2020
    Last edited: May 3, 2020
  9. skifree

    skifree A disciple of the blessed avi giraffe Moderator Ski Pass: Gold

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    The Mudhouse made are different to the Kahu made.

    So the blue & white ones are at least 10 years old.
     
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  10. Ziggy

    Ziggy A Local Ski Pass: Gold

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  11. Goski

    Goski One of Us Ski Pass: Silver

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    10-15 degrees would have been a justifiable warranty exchange. No wonder an edge hold would be poor at such an extreme angle. Cudos for a beautifully detailed post on the fix @Ziggy
     
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  12. Chaeron

    Chaeron OutLiar Ski Pass: Gold

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    pegasusSki and Ziggy like this.
  13. skifree

    skifree A disciple of the blessed avi giraffe Moderator Ski Pass: Gold

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    Maybe it’s time they were retired and turned into garden furniture.
     
  14. Ziggy

    Ziggy A Local Ski Pass: Gold

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    Wow. All these years of pattern base discussions.
     
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  15. Ziggy

    Ziggy A Local Ski Pass: Gold

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    There's life in them yet and I've had my money's worth already as an iso project. I've experimented with techniques I wouldn't have dared to try with young skis.
    I've now freehand bastard and fine filed the vertical faces and run a medium diamond plate over them.
     
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  16. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    5 deg bevel through the wax pocket will still edge like total arse. At least you had fun though.
     
  17. Ziggy

    Ziggy A Local Ski Pass: Gold

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    That's what the ski tech did with my first pair. It was decidedly better than 15.

    And yeah, it's been fun. I might start getting OCD about all my edges :rolleyes:
     
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  18. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    I have to say I'm not a fan of resetting edge angles by hand, takes ages. I am OCD about my edges once the angles are to my liking.
     
  19. Ziggy

    Ziggy A Local Ski Pass: Gold

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    Oh yeah, it's time consuming but that's a plus at the moment.

    I learned to grind metal when woodturning. You do a lot of tool sharpening in that. Then got into rehabbing old hand planes and bench chisels. The blade faces have to be flattened and honed first or you never get a good edge. Doing that by hand was a marathon, beaten only by hand flattening the sole of a #7 plane. Then I started rehabbing old axes. Their bit geometry was mostly crap and I got mechanised.
     
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  20. Ziggy

    Ziggy A Local Ski Pass: Gold

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    So to mounting NTN bindings....

    The Guides have marks for 3 boot size brackets. For 75mm bindings these should match the pin line?

    But for NTN my recollection is to line up the boot midsole with mid chord. Sound right?
     
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  21. Chaeron

    Chaeron OutLiar Ski Pass: Gold

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    For Tech bindings I mounted midsole to midpoint on the ski .... probably similar.

    This has been fine on the up and down.
     
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  22. Goski

    Goski One of Us Ski Pass: Silver

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    I'll use that method when I mount the Nordica Steadfast (made in 2013!) blanks in my garage with my first NTN binding. Which will probably be a Meidjo 2.1 with the new step-in plate or a Meidjo 3.
     
  23. Chaeron

    Chaeron OutLiar Ski Pass: Gold

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  24. Ziggy

    Ziggy A Local Ski Pass: Gold

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    Let's stay on topic.
     
  25. Ziggy

    Ziggy A Local Ski Pass: Gold

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  26. Goski

    Goski One of Us Ski Pass: Silver

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    Oops. My apologies for going off-topic. NTN doesn't have the 75mm pin line and my next mount will be an NTN. Though NTN mounts is also off-topic. Must say if I find some nice Karhu Guides I do know now to check the bevel angle before aquisition so thanks very much for the info on the bevel angle.
     
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  27. Ziggy

    Ziggy A Local Ski Pass: Gold

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    Suspect they'll all be wrong.
     
  28. Ziggy

    Ziggy A Local Ski Pass: Gold

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    When recycling skis you're likely to need to fill screw holes.

    There are pegs made for this. Or you can use epoxy.

    I prefer a brew I developed for filling voids in wood turnings, and that's 50/50 epoxy and ground coffee.

    Apart from improving the smell of the mix and reducing the amount of epoxy you need, it allows the filled hole still to be easily worked. It's plenty strong.
     
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  29. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    Not that teletips crowd. Touring focus pins on balance point, turning focus boot midsole to ski midsole. Halfway in between pins on chord centre. Somehwere either side of the center do your measurements, have a beer, look at the boot on the ski in different places and go with the vibe.
     
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  30. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    The pin line is the same as the end of the toe lug on an NTN boot.
     
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  31. Ziggy

    Ziggy A Local Ski Pass: Gold

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    Thanks TP. You're a champ.
     
  32. Goski

    Goski One of Us Ski Pass: Silver

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    Adding my thanks @Telemark Phat . A rather important thing to know if mounting say a Meidjo. Not easy to move it a couple of cm unlike a 22 designs where one could just drill two more holes plus one more for the heel riser to move it back or forth.
    Where to put the NTN toe might be useful knowledge for whoever buys the Karhu Guides Ziggy has on Gear Swap.
    https://www.ski.com.au/xf/threads/touring-telemark-skis-karhu-guides-175cm.87535/
     
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  33. Ziggy

    Ziggy A Local Ski Pass: Gold

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    Reference points on my new Annums ...

    1. Maker's pin line (marked on the deck)
    2. 50% of chord line
    4. Balance point
    5. 50% of running length

     
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  34. Chaeron

    Chaeron OutLiar Ski Pass: Gold

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