Radius Formula

[Bordy]

Does any one know or have the formula for Tip, Waist, Tail measurments to Radius?

[Ken B]

Nate has an on-line calculator here:

http://www.natew.com/frames.cgi/software/snow/html.Main

Click on the link for reverse engineering of snowboard geometry.

-Ken B

[Jack Michaud]

There is a simpler one that I forget, but I just doodled this out on a napkin:

R = X / (sin(180 - 2(arctan X/Y)))

X = half the running length
Y = sidecut depth

[John]

If you don't like trig an even simpler formula is:

sidecut radius = (L^2)/(8*d) + d/2

Where

L = running length (distance between the two widest parts of the board)

d = sidcut depth

all measurements are in meters, so the sidecut depth will end up as somthing lile 0.02m (1cm = 0.01meters)

[tilledog]

You don't have a turn radius on your boards and neither does yo mama. They're all straight so actually, I guess you do. Infinity!! (+1)

How's the pow pow up there?

Davo

[Mellow Yellow]

ok.... my head hurts now.....

[Jack Michaud]

Originally posted by Bob Jenney
Not to point out the obvious, but y'know boards don't have a "radius" per say?

A side cut is made up of a parabolic curve. Manufactures use the word radius because it’s easier to communicate.

Actually many mfr's use radial sidecuts, Burton for one. Some use parabolic (quadratic), some use elliptical, some use a blend of multiple radii, etc.
-Jack

[tim]

Uhh, it may not be very obvious, but the difference between an parabola and a true radius is very small, less then 0.02 mm (0.001") for a board of common dimensions (length/radius ratio). I still haven't met the guy who can sharpen my edges to this accuracy.

You can also forget about the +d/2 in the simple formula (neglectable), also:

R=L^2/(8*d)

Which accidentally (well, actually not accidentally) is the exact formula for a parabolic sidecut.

Tim