Ski Press I-beam Sizing

[skimann20]

Hey Gang.

I've been searching my nuts off trying to figure out the size of I-beam to use for my ski press and it seems that everyone is using different sized beams. Is there a reason there isn't a sticky with this info that everyone can input?
Say: Size of beam, cavity size, size of air bladder, PSI pressing at, bolted/welded, Frame or beam spacer (size), amount of deflection.

From the looks of all the presses, everyone is shooting for a particular Moment of Inertia for their beams?

Here are the sizes and info of beams that I have found used so far:

W 14 x 38
W 12 x 40
W 12 x 26
W 10 x 26
W 8 x 31
W 8 x 28

and there moment of inertia:

Ix Iy
(in4) (in4)

385 26.7
310 44.1
204 17.3
144 14.1
110 37.1
98 21.7

data from here: http://www.engineeringtoolbox.com/ameri ... _1319.html

Assuming an 8' press and max pressing pressure of 70psi: is there a minimum Moment of Inertia that should be cleared? or am I barking up the wrong tree.

[twizzstyle]

Different cross sections (and therefore moments of inertia) will only change the amount of deflection you get, for a given length of beam and amount of pressure. I don't think there is a specific amount of deflection you want or don't want, the less the better.

I think what often drives the size of beams folks use is just what they were able to find. That's an assumption, but I bet most people got beams cheap from scrap yards, etc, as opposed to buying "new" from a steel yard.

[NinetyFour]

Different cross sections (and therefore moments of inertia) will only change the amount of deflection you get, for a given length of beam and amount of pressure. I don't think there is a specific amount of deflection you want or don't want, the less the better.

I think what often drives the size of beams folks use is just what they were able to find. That's an assumption, but I bet most people got beams cheap from scrap yards, etc, as opposed to buying "new" from a steel yard.

I bought mine brand new from a steel yard, 8X8", 8' long (4 of them) to use in my press. Still building my press but the beams at 31 lbs/ft, I think the forces (although enormous) and beam deflection will be negligible. I searched and searched and searched for I-beam and wasted probably 2 weeks trying to research this issue. In the end I just opted for the 8x8"s because I've heard of them being used before. Good luck with your search!

[MadRussian]

I found my I-beams on side of the road. In fact my press made from five different sizes I-beams only because what I can build press from was in that pile.

MA steel yards always have used I-beams. Mid-sity steel near Fall River probably have one you need and they will cut it for you.

[Less (antonym)]

I agree with twizz, it seems the selection is a bit hap-hazard.
We chose our sizes based on what we could find that added up to an appropriate width for the skis we want to make. On paper any of the sizes we looked at (the smallest was130mm wide x 200mm tall) were going to give much better deflection results then the hollow sections that we could lay our hands on. That said we are yet to run it up to full pressure to see what the deflection really is.

[skimann20]

I agree with what everyone has said. Particularly the part about "we used the beams that were available" I'm going through the same thing right now. I just think that it would be nice to have a sticky for each of the pieces of equipment. That way the up and coming builders can see all the different varieties out there.

MadRussian: thanks for the advice, called and emailed them. looks like they have what i need. just need someone there to actually quote me on the pieces. keeping my fingers crossed.

[MadRussian]

I agree with what everyone has said. Particularly the part about "we used the beams that were available" I'm going through the same thing right now. I just think that it would be nice to have a sticky for each of the pieces of equipment. That way the up and coming builders can see all the different varieties out there.

MadRussian: thanks for the advice, called and emailed them. looks like they have what i need. just need someone there to actually quote me on the pieces. keeping my fingers crossed.

did you call to Annex? At annex they can give you general idea of price. btw they have list on their website what's available from annex. The best way for you would be go there.

[skimann20]

Madrussian: yup, Paul actually sent me an updated list of the steel they have. Sent an email back on the ones I want and I'm waiting for a reply. I'm placing a call in the morning.

Does anyone know what the price diffeence between "stock" steel and "scrap" steel is?

[cainguy]

The price difference is between $.20 and $.22 per pound Canadian in my area.