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[skidesmond]

Well I guess I'll chime in......

a.badner - On the video clip you posted, play the clip to the 30 sec mark, then jump to 1min 30 sec. You'll notice a HUGE deflection. I ran the video a few times because I thought maybe the camera had moved but the camera was stationary. No, the press didn't blow apart (that time) but a press that moves that much isn't worth anything. You may not notice the deflection while inflating the hose slowly but that press must have defleced at least an inch or more. So much for camber.

And because some kid posted a video of a something he made doesn't mean squat. The internet is full of B.S. You need be able to weed out fact from fiction.

On the advice that's been given.... Had I not listened to and read just about every post on building a ski press I would have built an all wood press and been very disappointed, injured or both.

When a steel worker gives advice about steel take it. When a engineer gives advice about pressure, design,etc. take it. It's free! They know what they are talking about. The forces/pressure involved are mind blowing. Honestly I don't fully understand it all either. But when I don't know something I educate myself and listen to the experts. Sometimes criticism can be hard to take when you've put so much time, energy and money into a project. But it's been given so you can succeed and get that rush of skiing on you're own hand made skis.

I added steel to my press and I still get about 1/8inch deflection. My wood beams are 8in x 15 3/4in x 96in and those beams bend at 35 psi! I never thought they would bend. So I'm adding more steel to the middle.

About your ski press design, it's not about liking it, it's about safety.

I hope it all works out.

[MontuckyMadman]

facebook sucks.

your a prick, to alot of people.

well you haven't learned yet but calling people names on the internet will get you absolutely nowhere.

In fact when you take offense to comments on the web you are just showing your own ignorance.

And yes facebook sucks.
the interface is antiquated and the code is anything but solid. Consistent problems with loading pages and page redirects are very common and a nuisance.

This is why facebook sucks and is not as cool as the masses think.

Its just another half assed free interweb tool.

As far as the press is concerned if you have gusseted and trussed the design lets see pics. Then everyone will say sorry and yes looks good and you will get the pat on the back you so desperately need, apparently.

Everyone is evaluating the potential for deflection off the current pictures shown here and it will deflect considerably.

The skibuilders press in that pic is deflecting also and that is like at 30psi also. If you read this site indepth you would know about all the trials and errors and learning curve these guys have gone through and why they changed all their shit over time to be better and better.

I suggest you go back and read some of the old stuff on here. You will learn a ton. Life as with skibuilding is more about patience than anything else, oh and money.

[doughboyshredder]

.......

[twizzstyle]

So to try to steer this thread back on topic a bit...

Lets say you add 100 vertical supports to the sides with some kind of crazy non-stretchable unobtanium. So vertical deflection is no issue.

But what about the top? Do you have anything spanning the top? (other than that 2x4 box section stuff) The biggest issue I personally see is the angle iron itself, being an open section it takes almost no twisting load at all. If it were a boxed section then you'd just have to worry about bending, but since its angle, as DBS put it, you're going to be looking at a pretzel. Even if its supported on the sides, I could see the top web twisting upward.

[Rowen]

Please dont be anywhere near this when you inflate it.

[nzskier]

Im a Uni student studying industrial design and if im not at uni im reading and learning as much as i can about building skis and what not.. I know everything I know in large to this site and all the threads. I was amazed to see you start this at 15. I am disappointed though to see you toss peoples opinion so quickly and I do hope you don't fire up that press. Head Monkey had a good point

Constructive criticism is a valuable gift. Sometimes it’s hard to take, and how you take it is a reflection of yourself not of the one giving it to you.

and its actually not that hard to bend a bit of flat bar..... even new condition and yours is rusting out at least built it out of RHS.

Your press will be like pushing on the ends of a Popsicle stick it will bow and snap. Think about it.

[a.badner]

two things. look at first post. n=from now on im putting only things on the first page.



and

school started here in Canada.

my classes are ( in chronically timed format )

University Physics
Advanced function Mathematics
Extended French
University Chemistry



my father and i did some stress/force tests on the metals at his work.
we used some sort of a gigantic press with a force needle scale on it and placed the testing metal on two support and the needle was placed in the middle.

some thing like this
__
!
I I <- the i's being the supports. the exclamation mark being the force measuring device and the underscores being the press.

the angle iron deflected exactly 1/2 an inch at/around 146 000 pounds.

and the one inch thick steel square, 1/2 inch at/around 240 000 pounds.

and we only decided to do these tests because of the advice on ski builders.

according to those results, i don't think i will be

[shopvac]

how big is the point on the exclamation point pressing on the material? The deflection of 1/2" under 146,000lbs might boil down to a very small psi which would be bad. If the area was 1 square inch then this might work out for you. Sounds like you are learning a lot and getting to play with some cool tools at your dads work.

Keep up the good work, but please listen to the advice above as there are some very helpful folks on this forum that are trying to help.

[twizzstyle]

Nice work on the tests, that's what we like to see (sounds like you've got access to some legit equipment too! nice!).

I'm still convinced your angle iron will twist though, but you do what you do.

(I looked at your first post and there were no updates)

[twizzstyle]

Also I'd be curious to hear some more details about the test you did. So it sounds like you did a point load applied at the center of a bar supported on either end.

How long was the bar? A short bar will barely deflect, where as a long bar (i.e. length of a ski press) will deflect a lot more. Also, how was the load applied to the angle iron exactly?

[a.badner]

ok well the test went like this.

i had the exact same angle iron

(190 cm long) propped up on 2 steel supports (1/2 inch tall and when the angle iron hit the base of the press i stopped the load force and read the peak weight applied) placed at each end.

then the device/scale head was attached to the super large press head.

the device's measuring scale head was like a 2'' wide cylinder made of some kind of extremely hard steel ... maybe carbide? my dad said it was really expensive, and stressed to not hit the cylinder with anything. so i think it could be a kind of ceramic too?

i did three tests for the angle iron,

1. placed the cylinder on top of the corner of the 90' so upside down v from a side view

2. placed the cylinder on the bottom part of the 90' facing up so like an L with the cylinder on the L's extension thing. from side view

3. ( this one was hard ) placed it on the 90' iron part, so L with the scale on top of it.

then averaged out all the tests. most of them were around the 146 500 area any ways.

and in no test they twisted.



i dont know what is wrong but every time i go to edit the first post, and post it, it loads then tells me to login, then it goes to the index screen erasing what Ive just said

[twizzstyle]

Something is fishy here. (sorry, I don't mean to keep pestering you )

If I stand on a 190cm length of angle iron supported on the ends, I can probably bounce on it and get it to deflect more than 1/2" (and I only weight 130lb)

150,000lb is astronomical, it seems like something is off on orders of magnitude, or something. I'm puzzled. By my very very quick online math (using some online beam calculator) I'm getting 0.5" deflection around 1000lb (thats a 2" angle iron, with an assumed thickness)

&#948; = F*L^3 / (E*I*48 )

There's the math. delta is the maximum deflection, F is force applied, L is length, E is young's modulus, I is moment of inertia.

[a.badner]

(190 cm long) propped up on 2 steel supports

**** 19cm ****
sorry, i dont review what i write before posting

[doughboyshredder]

........

[MontuckyMadman]

your posts are becoming rather confusing. .5 inch over 19CM? That's huge.

But the weight force is huge as a point load so.....

Just think about it man. If I start flinging around a big 'ole piece of angle and slamming it into things and trying to bend it the way the stress exists in a ski press, I'm going to succeed.

If I take a big ass piece of heavy gauge tube its gonna be a different story.

I'm lucky I have a college degree, so just use your head, all signs point to taco.