Anatomy of a Runner, from Henry Bossett
Crown– The portion of the runner that lifts off a flat surface to a specified height. For instance, I feel that .008″ of crown is a good point of reference, so I always check runners to see what length of the runner is .008″ or less from a flat surface.
Flat– The portion of a runner that is absolutely true flat when checked against a flat surface. Light will not show through this area of the runner when backlit.
Sharp– That section of the runner edge that is, in fact, brought to as fine an edge as can be achieved. This area will not reflect light back from the point.
Entry/Exit– The respective areas to the front and rear of the crown which measure more than .008″ above the flat surface. These areas are usually purposefully dulled, being made progressively duller as you move away from the crown toward the ends of the runner.
If I only had one set of plate runners, I would design them to have 20″ of .008″ crown and 5″ of flat. for sticky conditions, or small lakes and light air, 12″ of crown with 2 ” of flat would help acceleration at the start and when tacking, but would not have the top end speed of the longer set. Insert runners, despite their longer length, seem to work with similar crown and flat lengths.
Tips by Bob Gray, Grand Traverse Ice Yacht Club
- Decide on the basic runner profile and crown you want.
- Look at the existing profile on a true bar so you can adjust it with your sander.
- When sharpening, only make 4 or 5 passes on each side of the edge so as to NOT overheat the blade.
- After each run on the sharpener, place the runner in an ice water bath. You can line your runner box with plastic and fill it with ice water.
- After the runner cools, place it on the true bar and recheck the profile.
- Repeat steps 3-5 until you get the profile you want.
- One trick that works if you just can’t get the profile you want if to take a fine sharpening stone or diamond hone (red) and lightly touch up the profile until you get what you want. Once you have this, repeat steps 3-5 and evenly re-sharpen the whole edge.
- The next step is to take a riflescope on the proper fixture and check the straightness of the edge.
- If the edge isn;t straight you can use your sander or hone to straighten it.
- Ater the edge is straight, recheck it on your true bar to insure you haven’t changed the profile.
- Next, take a fine sharpening stone or diamond hone and run it from front to back on each side of the edge (each side of the fee). This will remove any burrs on the edge.
- The last thing to do is dull back the edge on the ends. Decide how much of the edge you want sharp, then use 400 grit wet or dry sandpaper to lightly sand and dull the edge, taking the sharpness off. The closer you get to the ends of the runner, the more you can dull the edge.
- I use an 80 grit belt on my sander.
- Here are some basic suggestions for crowns (to .008″) and amount of sharp:
Runner Type Crown Sharp Standard Plates 11′ – 13″ 10″ Bull Nose 14″ – 16″ 12″ 30″ Inserts 14″ – 16″ 12″ 36″ Inserts 16″ – 19″ 14″