Sidecut Radius
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Sidecut Radius
Anybody have some kind of relatively easy formula to figure the sidecut radius as long as the running length is known, as well as the tip, waste, and tail dimensions. thanks...KT
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doughboyshredder
- Posts: 1354
- Joined: Mon Sep 17, 2007 7:37 pm
These two threads might help.
Side cut shape: is it catenary,circle, parabola, elipse ...?
Translating sidecut radius
Side cut shape: is it catenary,circle, parabola, elipse ...?
Translating sidecut radius
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MartinJern
- Posts: 48
- Joined: Sat Jul 28, 2007 1:27 pm
- Location: Sweden
I'm having a sidecut problem aswell.
I dont know how to explain this so you understand, mybe because I dont understand it propely...
When drawing up a ski in snocad, it doesent mark the waist only the center of the ski. How do i determen the point of the waist?
What i understand is that the bigger the difference of with of tip/tail, the further back the waist is.
This becomes a problem when making a "pintailed" ski, that has a big taper tip/tail.
When messuring the printed template, the waist is allmost 20 cm behind the center of the ski... (148-120-128)
How do I know where the bootcenter and the high point of the core will be? !n this case it cant really be on the waist can it? It would be rediculusly far back....
I dont know if it made any sense at all, sorry for my poor explanation...
I dont know how to explain this so you understand, mybe because I dont understand it propely...
When drawing up a ski in snocad, it doesent mark the waist only the center of the ski. How do i determen the point of the waist?
What i understand is that the bigger the difference of with of tip/tail, the further back the waist is.
This becomes a problem when making a "pintailed" ski, that has a big taper tip/tail.
When messuring the printed template, the waist is allmost 20 cm behind the center of the ski... (148-120-128)
How do I know where the bootcenter and the high point of the core will be? !n this case it cant really be on the waist can it? It would be rediculusly far back....
I dont know if it made any sense at all, sorry for my poor explanation...
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knightsofnii
- Posts: 1148
- Joined: Tue Jan 08, 2008 6:02 am
- Location: NJ USA
- Contact:
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RaccoonFace
- Posts: 2
- Joined: Wed Dec 03, 2008 12:54 pm
If you know all the distances it is simple, and these steps assume that your sidecut will not be narrower than the waist of your ski/board. This explanation will present the solution for the radius of the tangent circle.
First, you know your running length, say 100 units.
Second you know where you want your waist, say 55 units from the tail.
Third you know your tip width, say 130 units.
If your waist is 100 units the difference between your waist and your tip is 15 units. (Tip - Waist)/2 = (130 - 100)/2 => 15 units
Your "x" value is the distance from the waist to your tip, in this case 65 units.
Your "y" value is the difference between your wast and your tip width, in this case 15 units.
To find the radius of your circle you just solve for "r" where r = k.
The equation of a circle is (x-h)^2 + (y-k)^2 = r^2 where k^2 = r^2, and h = 0. This yields: r^2 = x^2 + k^2 - 2yk + y^2.
The next step, isolation: k = (x^2 + y^2) / (2y)
okbye
ps I'd recommend that someone just skim over the explanation to confirm it's accuracy since it isn't difficult to make simple mistakes.
First, you know your running length, say 100 units.
Second you know where you want your waist, say 55 units from the tail.
Third you know your tip width, say 130 units.
If your waist is 100 units the difference between your waist and your tip is 15 units. (Tip - Waist)/2 = (130 - 100)/2 => 15 units
Your "x" value is the distance from the waist to your tip, in this case 65 units.
Your "y" value is the difference between your wast and your tip width, in this case 15 units.
To find the radius of your circle you just solve for "r" where r = k.
The equation of a circle is (x-h)^2 + (y-k)^2 = r^2 where k^2 = r^2, and h = 0. This yields: r^2 = x^2 + k^2 - 2yk + y^2.
The next step, isolation: k = (x^2 + y^2) / (2y)
okbye
ps I'd recommend that someone just skim over the explanation to confirm it's accuracy since it isn't difficult to make simple mistakes.