Core Taper Formula and Center Location for Alpine Mount

[dbtahoe]

I know this is a big chunk to chew but...

Is there a formula that people use to determine a good starting point for the taper from the mounting location down to the 2/3 mm?

OR are you picking a number out of thin air to start with and adjust as you test the skis?

Also what is a good setback from center for an Alpine mount AND does that also shift the mounting deck backwards as well.

Pressing in 2 weeks!

[hafte]

Have a look at this. I have entered most of the skis from this web site and the two I have made and skied. My skis have ~9.4 and 5 mm of deflection. The soft skis are fun and easy to ski the stiff ones are a real challenge to ski. This works well for a comparative analysis and can give you some idea of teh diresctio you will need to go.

http://www.skibuilders.com/phpBB2/viewtopic.php?t=486

Here is my write up on my skis

http://www.skibuilders.com/phpBB2/viewtopic.php?t=613

Good luck with your first pair!

Hafte

[dbtahoe]

~9.4 and 5 mm of deflection

I see the 9.4 is the core thickness. What is the deflectiion. I see a chart with it shown but what does if mean. Is it the flex under a predefined weight? Do I need to adjust that according to my weight?

Sorry if I don't understand the terms.

Thanks for the response.

[hafte]

Actually the 9.4 mm (9.7mm actually I have my SS here) is the deflection in the bottom graph. If you hover over the graph line it will show you a coordinate at that point. The only data that I have modified is the ski dimension data, running length, nose width, etc (stuff in the yellow boxes). The force applied is a ten Newton load and I have left that alone. The SS is good for making comparisons of known skis and to see if the flex curve of the ski is smooth. When I started using this I entered data from the gallery and looked at the curve and deflection mostly. And then read comments about how the skis worked to get an idea of where I needed to go. It’s cool to see how the mount length, thickness, and profile affect the flex of the ski. For me a deflection of 9.7 is too soft.

In working with this for a while the difference between too soft and too stiff is very small ~2mm in the mount area and .5 mm added to the tips. The length of the mount area has an affect too. Its just not as dramatic as the thickness. Remember this is a comparison tool. The accuracy is of the data is not what counts. It’s the consistency of the data entered that matters, and having something to compare the data with. So far I‘ve stuck to a simple build method and a simple model in the SS.

Also have a look at the data in the gallery. They have given lots of info out there too. Just remember Kam, Kam, Kelvin are ~ 150 lb guys so you need to adjust accordingly. This is where I started. The only thing I had trouble with is that the SS measures tip and tail start/end from the center of the running length, and some of the data in the gallery is measured from the cord center. When I entered the data from the gallery I had to make some assumption about tip/tail length to make the SS work properly.

Don’t take too much of what I say a as gospel. I’m in the same boat as most everyone here. I have two pairs of skis that have been ridden and one more yet to see snow. I think they’re going to be too stiff also. It was a bit too warm for the fast hardener I was using and the tails are too thick. The epoxy started kicking off before I could get everything under full pressure and not enough epoxy was forced out. I threw the SS out there because I have found it to be a valuable research tool and gave me a better idea of where to start and where I want to go.

Hafte

[flatlander]

If you want to get technical head to your local engineering library and look up ASTM standards. There is one for required binding mount area, location, screws, etc. Cheers.