:: View topic - Where to put my waist.

i am making my first pair of skis. they are to be 180cm long and have the dimensions of 130-100-120. now 100 is the waist width, just where do i put it on the ski, Ex. 100 cm from tip. please give me your input.

I snowboard.....but

you should definatly figure out what a ski is before you attempt to make one. The waist width is skinniest part of the ski and depending on your personal preference, located at or around the planned boot center.

sidecut radius will determine

General consensus is to work out the running length (amount in contact with the snow) and place the waist at 55% of the running length from the tip.

Eg. For a 180cm twin tip the tip and tail will be 15cm long each. So the running length will be 150cm. 55% of that is 82.5cm. So waist should be 82.5cm from the start of the running length (or 97.5 from the ski tip). Boot centre is usually placed at the waist point also.

Download Sno-CadX, it will figure out where the waist goes for you, then if you want to move it you can do that also.

I like to have the ball of foot (BOF) over the center of the running length. For this reason I tend to use a 50mm setback for boot center, regardless of ski length. But like everyone else has said...it comes down to personal preference and other ski geometry.

If you're doing a circular sidecut, you can't move the waist given some pre-determined width dimensions. They define where the waist will be, its just geometry. If you want to move the waist fore/aft, you have to change either the tip or tail width. If you make the tail narrower, it moves the waist back for instance.

you are a retard, you obviously dont know what point i am trying to make.

hum.. this is your 2nd message rybutler... a "thanks for those helpful replies" would have been a better start to show some respect for the guy who gave you an actual answer !

Even though DTrain's reply was a bit rude, we see so many people not reading the posts and directly asking stupid question that I cannot blame him. If you think people are gonna help you again with this attitude I think you're wrong !

Anywhere between 2 to 5 cm back from true center, so in your case 92-95 cm back from the tip. Read more, as in everything on this forum, post less.

The fact that you asked the question tells me that you dont have a good grasp on building skis/boards. Name calling wont get you anywhere.

Ok, lets start over....

Are you saying that you want to make an assymetric ski and thats why you ask this question?

you are a retard, you obviously dont know what point i am trying to make.

I do know what point you are making! I too have asked a couple of these gentlmen to hold my hand and guide me though my ignorant or brain dead building thoughts, and I read these forums/journals for almost a year before i even asked a question.

But even this retarted knuckle draggin' snowboarder knows where he would want his waist width on ski. Any where I preffered it. If you dont even have a thought or prefferance to the easiest of design specs, you should not even be reading this stuff. You belong at a mainstream sports outlet getting advice on what to buy, not what to build. My answer to your question was blunt but true. And If you were trying to make a point with that question, I dont think anyone got it. I can already see your next question....."where do I want me boot center?".

so ya.........actully didnt get the point.unless it was that you dont know a thing about skis!

Twizz is right. If you have a predetermined tip and tail width and you put your predetermined "waist" in a certain spot it won't actually be the real waist (narrowest point of the ski). I did this on the first few designs before realising that the real waist was behind the place where I thought I had put it.

My latest design I chose a running length and a sidecut and placed the apex of the circle at my waist point. This waist point and sidecut then defined the tip and tail widths.

You realise after a while that all the parameters are linked and the physical realities of geometry mean you can't define all the parameters independently.

Exactly Falls!

What I've been doing is setting my tip and waist widths, then adjusting the tail width to place the waist where I want it (which I do more or less by eye.... I'm a firm believer in the "that looks about right" philosophy)

Rybutler, I am assuming that you don't have a CAD program. My advice is to start using one and play around with it. Everything discussed here will immediately make sense. It takes some time to learn all of the functions and you will probably spend countless hours on your initial designs but for me that is half the fun. You can draw anything you damn well please and all your wildest dreams will come true.

The most current version of AutoCAD is free for "students"

at:

http://students.autodesk.com/?nd=download_center

I also have a a big how to post in my thread over at NS for those AutoCAD virgins who don't have a single clue on how to draw anything let alone a ski. Now it isn't the most perfect how to, as it was made in MS paint, but it should get a guy up and running and help with the basics. Thread:

http://www.newschoolers.com/ns/forums/readthread/thread_id/651776/page/1/

If you have any questions on AutoCAD (any year really, I still do all of my official work drawings on R14 as the student AutoCAD watermarks drawings) then hit me up with an inbox on here, or over at NS. Good luck!

I have always been backmounting my bindings quite far with the idea that I wanted to "push" my skiis into the turn. It works for me but I am more and more thinking that it has to do with core profile/style of skiing than sidecut waist placement. I know most skiis have this 55% devision but the new salomon http://www.salomon.com/dk/segment/all-mountain-ski.html

must have something like 70-80% setback.

We are making an experiment build right now to see how it works.

The binding will bee mounted as on the veneer ski but the waist is behind the heel.

Any thoughts on this are most welcome!

I'm always one to see experiments. Probably work best in powder. Seems to me you'd have a very long front part of the ski to control with a very short tail. If you get in the back seat at all there won't be much to help you back up, except strong legs and abdomen. I think on a groomed carving trail it would be squirrely. Keep us posted.