How to make cardboard water-proof?

[AaronMartinSole]

Wow I am amazed and astounded at the innovation involving cardboard described in this thread. It's poetic really. Like turning trash into treasure, pyrite into gold, coal into diamonds. Or more like turning four quarters into a dollar. I don't know what that means.

Originally Posted by mcrews

your in Nor CAL....are you near sacramento?
I bought 4ft x 8ft sheets wholesale at a place near arco arena.

But anyway, yes I am in Sacramento! Please let me know the location of this place! How much is it? Thanks!

[freebeard]

Paper Houses
Roger Sheppard, Richard Threadgill, John Holmes
Schocken Books, 1974 - Technology & Engineering - 133 pages

One of my favorite books, ever.

Back when I was building domes in cardboard the hot stuff was piano packing cartons. *Huge* pieces and double corrugated, but they had a wax finish. Are piano stores still around?

[Xist]

I dare Order99 to make a piano out of cardboard! I do not know what he would use to ship it, though...

[freebeard]

Cardboard Bike Helmet Better than Plastic | Gadget Lab | Wired.com

What about rains and sweat? No problem. Surabhi’s helmets mix the cardboard with a “waterproof acrylic compound” which makes them just as rain-resistant as the helmet you have now.

[Xist]

Is that supposed to get more people to wear helmets?

Do you think that they absorb shock so well because of the cardboard itself or the acrylic? I am visualizing Aerocivic-style nosecones made out of dumpster contents...

I lost four cars at least partially due to front-end collisions, although aerodynamic front bumpers might have actually hurt with the elk and the motorcycle [that went through my windshield]. Just thinking...

[order99]

Originally Posted by Xist

I dare Order99 to make a piano out of cardboard! I do not know what he would use to ship it, though...

Can I use the same cast-iron subframe that the piano makers use? Otherwise it's a no-go...The tension on on those babies is DEADLY...

As to Shipping, it would be Slooowww-

http://www.americanspeedster.com/



I WILL build me one of these when I feel solvent again-and the body panels will be 'glassed Cardboard of course..

[freebeard]

Here're two different ways of doing it, I'd label them egg-crate and monobloc. I'm not sure which method the claim is made for. Corrugated sheets laminated into a block is immensely strong.

In either case. it's the air that does it, allowing room for the paper fibers to crush under sufficient force. If you see a modern plastic bumper with the cover off, there is a plastic egg-crate inside.

order99 -- Don't forget the cup-holders! Also, this:

[order99]

I'm not sure which method they're talking about either-but the egg-crate version would be super-fast on the assembly line-

1) Stamp-cut the pattern on a die (1 sheet per second=1 helmet). Hand-off.
2) Hand-assemble helmet (2 minutes or less unskilled, 1 minute with proper training and an assembly form). Hand-off.
3) Carefully lift helmet from form, place on brim and use hot-glue gun to anchor brim to helmet and prevent slippage of parts, using dots of only 1mm or less (1 minute). Hand-off.
4)Stretch thin nylon cover over helmet and tuck, staple(1 minute).Place helmet upside down in waxed release mold, 20 to the batch.
5) Spray gun with two hoses, epoxy and hardener, thinned enough to atomize and mix midair in spray (less than 1 minute per batch). Leave in warehouse a minimum of 45 minutes.
6) Inspect, flip into different mold, treat exterior of helmet with spray epoxy(2 minutes due to increased surface and angles).Leave 45 minutes or more.
7) Inspect, transfer to paint rack for multiple enamel coats which act as filler for low spots(2 minutes).Leave 12 hours.
8) Inspect, scuff,re-inspect and send to booth for final coat(10 minutes).Cure 12 hours.
9) Spray adhesive and place interior foam inserts, package and allow adhesive to set during shipping(3 minutes).

The monobloc version will be much more labor and time intensive, I suspect-I am unfamiliar with any automated processes that would be able to accurately layer board in the necessary patterns and each layer would need to set while the next was added. Also, cardboard does not injection mold the way polymers do. The best I can come up with is-

1) Layer and press corrugated logs/blocks under pressure and seal.
2) Use CNC to cut helmets from logs, constantly reclaiming the MASSIVE waste for recycling back to pulp.
3) Run helmet through epoxy spray, keeping in mind that only the first 4mm or so would be soaked through-the corrugated board would provide protection regardless.
4) Steps 4 through 9 as listed for the egg-crate version.

From an economic/manufacturing standpoint, I think the egg-crate wins. From a performance standpoint however, I think the monobloc would be safer as the entire surface area of the latter has no reinforced 'ribs' to possibly punch through the liner as the egg-crate might under the right circumstances.

Love the Bonsai trike BTW-but one accident and you'd have to grow a new frame from scratch or deal with an ugly splice-and epoxy repair...

[freebeard]

From the article:

Because they are easy to build to order by scanning the buyer’s head and cutting the cardboard to order, it fits perfectly.

• Stockpile laminated corrugated blocks or 'billets'
• On order, use router bit in 5-axis mill to shape inside and/or outside
• wirebrush until paper fibers fill corrugations
• spray with 'waterproof acrylic compound'
• profit

I wonder how they attach the chinstrap/visor/head-mount video

And that bamboo trike? Proof that, like stripes and plaid, you shouldn't mix spoked and hubless wheels.

[order99]

I completely missed that part-custom cut to order and not mass produced in bulk? Definitely doable on that scale.
Any idea how deep this 'Waterproof acrylic compond is supposed to penetrate? I'd hate to toss a helmet just because of, say, scuffing it against a park bench or something...the article does mention 'as tough as a normal helmet' so I suppose that issue has been addressed already.May be we'll get a follow-up article soon..