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Sharpening Runners

February 11, 2006 - 03:14 — tldoroff

I am new to this site and live in Colorado. I just completed my iceboat up at my Dad's in Minnesota, a homemade DN, with a retrofitted mast from a Hobie Cat. She had one inaugural run, but side slipped terribly in the wind, and the winds in CO are incredibly intense.

I was given some old runners from a boater in South Dakota, but they are terribly dull.

Is there anything that describes how to sharpen them and at what angles/inclination and what edges get sharpened. I'm a little confused on how to do this, but want to do it myself. I have a shop grinder, but could also make a jig and use my belt sander. If anything could point me to pictures or visuals, that would be great. I am also interested in buying some runners for her if anyone knows of sources.

I can't find a site like this anywhere in CO -- good ol' Minnesotan's --

Anyone who could advise me, I would be most appreciative. Otherwise, I'm going to have to go mountain biking, and that's a lot of work! There's ice here - and if anyone ever visits and wants to boat - look me up!

You may also email me at tom@alifewelllived.org

Comments

February 14, 2006 - 03:41 — GeoffS

A start...

Check out the article: Terms Involved in Understanding Runner Design

Some basics:

  • The angle at the edge whould be 90 degrees (45 deg from each flat side of the runner)
  • The side-view of the edge should be smoothly curved from the front of the runner to the back.
  • The front and back ends of the runner edge should be about 3/16" off the ice.
  • The center of the curve in the edge (where the runner sits natually when you push down on at the mounting point) should be just ahead of the piviot point.
  • For 30 inch runners (the std. DN plate runner), the distance between two 0.008" shims (heavy paper is close) slid in between the edge and a very flat surface so they just barely bind should be about 12".
  • Make sure there are no nicks in the edge, and that there are no "hollows" (places where the curve reverses and goes up briefly)
  • You can use a decent straight-edge to get your runners close (I used to use a level that I'd carefully checked straightness).

Here's another discussion of runner shaping/sharpening.

Also, you might want to search and/or post a question on:

Cheers,

Geoff S.
DN US-5156