Ski Builders Forum

Hello, I am building my first press and was hoping someone could double check my beam deflection calcs. I came across some 6"x6"x1/4" tube steel. My design calls for 3 of the 6"x6"x 9' long on the top and 3-6"x6"x9' on the bottom. The tube steel beams will be sandwiched by 2-6"x6"x16" stacked and perpendicular to the 9' beams connected with grade 8 bolts. My cavity will be 12" tall, 96" long, 16" wide. My calc. criteria is 75 psi. My calculated deflection is: .267" and Stress=25,043. Thanks in advance for anyone who can help me verify these calcs. From my research this deflection and max stress is within a normal standards?

Adam

I've seen designs in the forum using the same type of material you are using. While I can't verify your numbers such as deflection etc. But check you're stress number. By stress do you mean total psi? How did you calculate 25,043?

My understanding is that if you're pressing at 75psi, that's 75 pounds per square inch. So figure out the total square inches where the pressure makes contact with the press (or forms), multiply that by 75psi and that gives the total psi.

He meant stress as in stress in the beams, not total force on the beams. Stress is measured in PSI.

It's been so long since I've done this stuff in school I'm not sure I'd want to even try. Solidworks has some very rudimentary FEM so I could whip something up and see if its close to your numbers.

Thanks for the input. I do mean stress in the beam. If I could shake off the cob webs from my college engineering classes I could remember the yield strength of steel and deflection calculations. I am 99% sure my design is safe but thought if anyone had a spare second to verify my calcs it would make me feel like I know what I am doing. I can always add angle and all-thread sandwich in the center if deflection is an issue. From a ski/snowboard building perspective .24" of beam deflection shouldn't effect my camber too much, correct?

Thanks!

Well figure that's 1/4" camber lost, its not tiny. Of course you won't know for certain until you build the thing and inflate the hose.