Thickness profiles

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Cadman
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Thickness profiles

Post by Cadman »

I want to experiment putting the thickest point of the ski profile forward of the normal position that most people do. I was thinking 50+ mm. I have seen thickestest points at the waist, Mid running surface and would like to try going forward of there. Has anyone had any experience at thus and what was the performance result? Thanks
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vinman
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Re: Thickness profiles

Post by vinman »

I usually create a flat mounting platform between 375 and 300 mm in length. This is usually ~200 -225mm forward of the waist of the ski and ~150-175 mm to the rear of the the waist. I vary this depending on what length ski and or how stiff I'd like the ski to be. I also at times play with the length of how long a make my tip spacer area ( 2.2mm thick) to vary flex.

I have very good results in terms of feedback from customers about performance.
Fighting gravity on a daily basis
www.Whiteroomcustomskis.com
serchman
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Re: Thickness profiles

Post by serchman »

vinman wrote: Mon Sep 06, 2021 5:24 pm I usually create a flat mounting platform between 375 and 300 mm in length. This is usually ~200 -225mm forward of the waist of the ski and ~150-175 mm to the rear of the the waist. I vary this depending on what length ski and or how stiff I'd like the ski to be. I also at times play with the length of how long a make my tip spacer area ( 2.2mm thick) to vary flex.

I have very good results in terms of feedback from customers about performance.
hi!! thanks for sharing.
For example, in a lenght ski from 1780mm, i do normally a ABS tip of 120 mm and an ABS tail of 50mm. then it's the wood core, in my case Ash. in increases from 2mm tip, and 2mm tail til the center of the ski, where i place 100mm flat surface, same as you. this flat surface goes from the geometrical center of the ski, until the effective mid point -100 mm. these are the 100mm i go flat on the maximum thickness (10,5mm).

Resume: side view: Tip ABS, Wood Core, Tip ABS
what do you think about this? it's a huge difference with the 300mm you mention.. and the 200mm effective center you mention.
thanks for the comments.
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vinman
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Re: Thickness profiles

Post by vinman »

I can't find the document but there are ISO standards for flat area in the mounting area of a ski. I'm not sure what it is specifically anymore, but I do know that it is larger than 100mm. As best as I can recall it varies with the length of the ski and is in the range of what I mentioned. I may have my front and back backwards in that last post. If you think about where your boot sole mark is it is closer to the from of the boot than the back. It would make sense that the shorter area of the mount zone would be in the front of the mount zone. The screws on most toe pieces have a smaller foot print than the screws of the heel piece.

I know that I read that someplace a long time ago and it is much larger than you think it is. But if you arrant selling anything it really doesn't make much difference. You can build whatever you want.

Your overall core thickness with also have a big impact on how big you make your mounting area. Thicker cores are stiffer. If you have a very large flat area for mountain it will also make the ski stiffer.

I have found a decent compromise for most of my core between mount zone length and overall core thickness. I can now vary this slightly to customize the flex for different lengths of skis.

I hope this helps in some way.
Fighting gravity on a daily basis
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Cadman
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Re: Thickness profiles

Post by Cadman »

Thanks for the feedback. The variance of shape at the center of the ski has mostly to do with minimum flatness in relationship to screw depth and binding mounting areas. ISO 8364 is the specification that you are referring to. Section 4 states that there is a maximum thickness and flatness at a certain point forward and aft of the mounting point and the distances vary in the size of the skis. In other words, the shape of that area can only change by so many mm along their stated distance. I believe that also has something to do with the length of the bindings being mounted. Too much change in thickness could have an effect on the way the binding works.
Section 6 states the maximum thickness so you don't end up with your screws protruding through the base.
Mainly what I am interested in is if you have built any core profiles with the thickest part forward of the MRS or waist. I don't do any profiles with flat sections on them. Most of the skis that I have measured for the main ski companies have a more bell shaped profile. They do vary from a more pointed profile to a more gradual long bell shaped curve. I have found that the more pointed profile tend to be tougher to ski but very precise.
PM me if you want more specific information.
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