Building a ski/snowboard press 1

[mcfridge]

Hi everyone,

I have decided to build my own press for making skis/snowboards. There is a lot of information out there on how to do this:

http://www.skibuilders.com/

,

http://www.grafsnowboards.com/

These sites are a lot of trial and error, so I wanted to take more of an Engineering approach (this will be my first question of many). I have already chosen some steel I-beam for the frame, and they are getting cut and drilled next Friday. If you go to this page

http://www.grafsnowboards.com/pressidx.htm

and go to the 6th & 7th pictures down, you can see a bunch of little bars strung together right under the top beam. They call this a cattrack, and it helps to distribute the pressure.

Now, I wanted to use Aluminum (because the press is already heavy enough) so I called a local place, and they had 1/2"x1/2" aluminum tubing, but the wall thickness was something like 1/16" (can't remember exactly). The "bladder" (a bag fille with air) pushes down on top of this with a maximum of probably 80 psi, over a length of about 90" and width of about 20". Is there a way to determine how thick the walls of these tubes should be to withstand the force? (sorry if this seems like a simple question, I'm having trouble with it). Is there any other recommendations on something I should try instead of these Aluminum bars? Thanks a lot.

 

[Pressed]

If you pick a solid metal over tubing you should be safe.

Otherwise test a piece of tubing.

(P = F/A so P * A = F)
--------------
Cut 1/2" x 1/2" tubing by 1/2" long. A = 1/2 x 1/2 = 1/4 in^2

P * A = F so 80 psi * 1/4 in^2 = 20 pounds

So that 1/2" cut of tubing is going to be loaded with 20 pounds. To be safe it should hold more than 20.

A 2" long piece of tubing would have the area of 1 in^2 and be loaded with 80 pounds.

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