TJI press

[CAFactory]

Over the last couple of months I have begin to assemble my snowboard press, and now I am close to being finished and preparing for pressing after many months of lurking and research on this forum. I have built it with TJI 460's (Not quite sure what that means except they were the bulkiest and tallest of the TJI's I had access to). The press is 14 inches wide, and has a 6' long cavity. I was hoping to make it longer, but I only had so much I-joist material. The ends are caged with 3/8'' welded angle iron. My cat track is not pictured but is made out of 3/4''x1.5'' doug fir, with .75''x.75'' sections in the tip and tail. Please post up any comments or suggestions.

[skidesmond]

Have you pressure tested it yet and at what psi? What's the deflection if any? I was in the process of making a similar press last year using wood I beams but in the end make wood beams instead from 3/4 OSB plywood. But at the time I didn't have any steel either, but eventually got some from a buddy of mine.

[CAFactory]

I have tested it up to around 25 PSI, and have no visible deflection so far. I'm going to get a regulator soon and a safety valve, and will report back on pressure once that's complete (my compressor is antiquated and not sure how accurate the gauge is). I couldn't find any numbers on the TJI's to calculate strength, so I don't think I'll be going any higher than 40-45. Definitely trying to stay on the precautionary end when it comes to the forces involved.

[skidesmond]

I didn't do calcs on my press. I pressureized the hose to about 35-40 psi slowly. That's as high I want to go and still live to talk about it.

I'm interested in the amount of deflection. I didn't think mine deflected at all until I measured it. I measured the deflection simply by measuring the distance from the floor to the top of the bottom beam before and after pressureizing. It deflects about 1/8 inch which isn't noticable to the eye but that 1/8 in. of camber you'll be losing.

See http://www.skibuilders.com/phpBB2/viewtopic.php?p=18214 for a picture of my press.

The cat track sounds fine.

Be careful and good luck!

[Alex13]

Desmond - you'd probably be right. True, the pressures are pretty huge and there's a lot of force, but those beams are very heavy. It's highly unlikely that if they did fail, they'd be displaced very far. The hoses will only expand so much. If you ramp up slowly you're unlikely to cause any serious injury. Having said that, I'd stand fairly well clear while testing, wear safety goggles and ear protection. This of course doesn't apply to presses with lighter weight components i.e. mongo style, cordura style.

CAF - nice looking press. Glulam young's modulus can be found here http://www.gltaa.com/product.htm which will give you rough figures to work from. You can calculate the area moment of inertia of the I beam yourself, and do simple load calcs from that.

From http://en.wikipedia.org/wiki/Second_moment_of_area

[Richuk]

I'm a but jealous that you guys have been building with wood and I busted my balls with steel lol. One thought though, is it worth vertically laminating some of the pieces that make up the beam - chopped strand perhaps?

[CAFactory]

Skidesmond-
I actually got the idea from my press from your thread, and partly from a thread from a couple years ago that involved TJI's. I really like the way yours is configured, and that how big of a cavity you have. Very Nice!

Alex13-
I appreciate the numbers and equations for the beams, I will run those soon. It will be nice to have a rough idea of the pressure I want to safely run at. Thanks!

Richuk-
That's an interesting idea, and might help eliminate any deflection across the width of the beams (if there is any). When I test the press to higher pressures I'll look and see if it might benefit.

[skidesmond]

I'm a but jealous that you guys have been building with wood and I busted my balls with steel lol. One thought though, is it worth vertically laminating some of the pieces that make up the beam - chopped strand perhaps?

If I was do it over again and still use wood I would have used glulams. They are already sized and have stats on the loads they can carry. I was pretty ignorant about the forces at work. It was a lot of work to cut 7 sheets of OSB plywood, plus a lot of sanding was done to make them as flat as possible. Glulams should already be fairly square and flat, just bolt them together. That would have been a big time saver. Live and learn. But I'm happy w/ my results so far.

[CAFactory]

Here is the nearly finished press, despite missing a few bungees and needing adjustment to the cat track. Recent paint just put me around $125 final tally. (Angle iron was free). Tested to 40 PSI deflection was around a 1/16 of an inch with the tape measure test from ground.

[chrismp]

your tip/tail molds look interesting. how did you make them?

[skidesmond]

Wow a pneumatic press for $125. That's awesome. And only 1/16 inch deflection is not bad at all. The press has got to be a lot lighter than mine. What's the dimensions of the I joists? Looking forward to seeing some boards from it. Nice job!

[CAFactory]

chrismp- I was wondering when someone was going to notice that. After many attempts with the router, I couldn't get a uniform curve across the molds. My router is old, and just about only will cut base well. The way I did my tails is with a table saw of all tools. It is made up of laminated 2x4, but the laminations are the opposite direction of how others do theirs. The angle of the cuts gets progressively vertical after the rocker section. Once I laminated the 2x4's together, I sanded with a curved sanding block, to smooth out the transitions between the boards. I will have 1/4 inch buffer at least between the mold and the board being pressed so hopefully the strait sections aren't very noticeable.



skidesmond-
Thanks, it has taken a while to get all the materials as cheap as I did. Thankfully a wood salvage yard had the TJI's for $1 a foot, which really helped out (I think they retail for double that). They are 12'' top to bottom and the top and bottom parts of the "I" are around 2'' deep and 3 5/8 across. The vertical beams were surprisingly light especially when they didn't have molds on them, but were just awkward to setup. With 2 people the beams were fairly easily lifted into place.

[chrismp]

maybe you should try to make your kicks like capita did with their flatkick technology. that would give you only a small curve to sand right.
our snowboards have tips like that and i really like the way they ride.

[CAFactory]

Wow, I just saw the diagram of flatkick, and that's sorta similar to what I have. Does your mold have as drastic of a kink in the tips and tails as the "flat kick" diagram below has? (Where the "Wahpow" arrow points) And how do you feel like it effects the ride?
http://grousepark.files.wordpress.com/2 ... boards.jpg

My mold has two slight curves or kinks where the "Wahpow!" arrow points and then straitens out...instead of one drastic tip "kink". One of my reasons for making my tips like this is because I've never been a huge fan of tips that turn up greatly or have a small radius, as I feel like they don't plane over soft snow as easily.

[chrismp]

yup, my tips look pretty much the same, maybe a little less steep though.
i've found this kind of kick to ride really well. floats nicely on pow and gives a good platform when buttering.