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Need some help regarding corrugated cardboard

PostPosted: March 15th, 2010, 6:09 pm
by burgerkong
Pretty much a newbie here, and need some help on this little project of mine (don't crucify me if I broke a design rule, I am an engineer first and foremost). I am considering Making a derivative of the Gehry cardboard chair when I have time this summer and have secured a bunch of cardboard from uline. What I need help on is the cutting portion. I'm in the process of finishing this up (still have some more layers to cut out):

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Which is just a basic headphone stand, but it's taking me FOREVER cutting out all the contours with an Olfa snap-off knife. Is there a faster way? I can't imagine the amount of time needed to cut 60+ cardboard layers with a knife, should I look for laser cutters? Or will the knife do the job?

Also, a related question. What's the best way in laminating the layers together? I've been using tacky glue, should I change to something like contact cement or Elmer's?

Thanks, Brendan :mrgreen:

Re: Need some help regarding corrugated cardboard

PostPosted: March 16th, 2010, 12:47 am
by mipe19
Funny you mention cardboard chairs because I recently finished up a cardboard chair myself.

So, if you're going for extra clean precise cuts, by all means use a laser cutter (I did). It's quick and easy, but if one is not available you can always cut it by hand. You can always sand the cardboard down to give it a nice soft texture. I think on Gehry's chair the underside was left furry and the top was clean. There is a spread in the last issue of ID magazine near the end with a in depth look into how Gehry's wiggle chair was made. I know he had to use a few dowels to provide a little more strength.

The hard part is trying to get all the pieces flush. You might have to build a jig that'll let you slide each piece in precisely.

As for glues, wood glue seemed to work best and one of my classmates made his own wheatpaste and that held together surprisingly well.

Re: Need some help regarding corrugated cardboard

PostPosted: March 16th, 2010, 8:38 am
by iab
Any corrugate packaging manufacturer, including Uline, can cut a custom shape. Call a few to get costs.

As for glue, I'd try a watered down white glue you can apply quickly and thinnly (yeah, I know, probably not a real word) with a brush to the corrugate. Do some experimenting an let us know the results.

Re: Need some help regarding corrugated cardboard

PostPosted: March 16th, 2010, 9:03 am
by PackageID
We use a CAD table to cut all of our samples. This is a cutting table that uses a knife and cuts from a CAD file. You may be able find a packaging prototyping firm that could cut them for you, but it would be pretty pricey. I was thinking and have not done this before and can't believe I am recommending it, but you could glue all you pieces up un-cut, draw your shape out on top and cut it with a band saw. Don't know if it would work, but it sounds pretty reasonable.

As far as glue....Wood glue works great for these type of projects. Corrugated boxes are glue with hot glue or the industry term is "Hot Melt". This could work, but with a normal house hold glue gun you will need to act fast as the glue dries quickly.

Re: Need some help regarding corrugated cardboard

PostPosted: March 16th, 2010, 9:46 am
by burgerkong
The problem I see with cutting up a glued brick of cardboard is that the bandsaw blade has to be REAL sharp and have a large TPI. Chances are that the edges will also fray giving a fuzzy cut. I can try that, I have a huge bandsaw handy in my shop. I may just decide to cut it out by hand, gluing 2-3 layers at a time and then gluing those together with other 2-3 layer pieces and getting a thicker part each time. I'll try wood glue, since I have plenty of it. Planning to roll it on with a paint roller, should give me a consistent glue thickness compared to brush.

Thanks, Brendan

Re: Need some help regarding corrugated cardboard

PostPosted: March 19th, 2010, 4:57 am
by Travisimo
I don't know what kind of laser you have access to, but sometimes it leaves a scorched edge on cardboard... I prototyped some packaging on a friends machine and it was a noticable discoloration.

Another idea, rather than glue, design in a jig (like mentioned earlier) - especially if you laser cut.The advantage is that it might be easier than tedious gluing and more recyclable (which might be a good aspect for your review)

Re: Need some help regarding corrugated cardboard

PostPosted: March 19th, 2010, 9:23 am
by Boosted561
As PackageID stated you really should get the sheets cut on a plotting table. The plotting table needs to have a reciprocating head to cut corrugate. Some places have plotting tables without the reciprocating head and that's only for paperboard.

You should use cold glue to maximize the strength of the bond. The hot glue will not be suitable for large surfaces. When you use the cold glue, use a minimal amount to avoid the board from getting warpped. Do not use rubber cement because you will not get the appropriate bond. We use a formulated white glue like Elmer's.

I notice you have the fluting in a different direction which doesn't really do anything to enhance the strength. The fluting needs to be along the same axis in which the most force will be applied.

If you can specifiy the board grade, make sure to ask for mullen board and not ECT. The fibers in mullen board is multi-directional which makes it stronger along various axis. The ECT grade board has uni-directional fibers and it's only strong in one axis.

Re: Need some help regarding corrugated cardboard

PostPosted: March 19th, 2010, 9:36 am
by PackageID
I was waiting for the GPI guy to come in and give us the real run down on corrugate. Thanks Boosted.

Burger I would listen to Boosted response. He works for one of the larges paper manufacures and knows what he is talking about.

Re: Need some help regarding corrugated cardboard

PostPosted: March 24th, 2010, 11:49 am
by burgerkong
Thanks for all the help guys...reason I chose to cut the flutes in opposite directions was because it looked better that way when layered, I'll remember to keep the flutes running in one directions when I make my chair in the summer. BTW, some completed pics:

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Brendan :D

Re: Need some help regarding corrugated cardboard

PostPosted: March 24th, 2010, 1:41 pm
by Lmo
Got in on this one a little late...

Other than the 60+ layers you mentioned, you did not indicate that this was a production situation; or what volume of these displays are required. That said, if you're going to continue, or must continue, cutting by hand, make a cutting template* out out of masonite, or aluminum sheet. It's much easier to mindlessly run your knife around a template than have to concentrate on following a line ... sixty times.

* If you have templates other, less skilled, helpers can be enlisted to help with the cutting chore. Watch your fingers while engaging in "mindless" operations...

I'd use a "regular" utility knife (stronger and easier on the hand) rather than a snap off (the blades flex more laterally).
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Adhesive? 3M77, or 3M99 - not cheap, but definitely fast.

Re: Need some help regarding corrugated cardboard

PostPosted: March 25th, 2010, 11:48 am
by Mr-914
Burger: Thanks for posting this. I've always wondered about the Ghery chair production too.

I really like all your photos. You have a great looking product there!

Re: Need some help regarding corrugated cardboard

PostPosted: April 28th, 2010, 11:52 am
by LabRats
Sorry, just saw this maybe a little late. Have you completed this project? PM me and I can look into helping you out getting this cut.