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Forum topic by RickInTexas posted 05-10-2007 12:49 AM 1304 views 0 times favorited 9 replies Add to Favorites Watch
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RickInTexas

45 posts in 2797 days


05-10-2007 12:49 AM

Is there any source that give how much you can free span say 3/4” plywood without is bowing under common loads? Or if you add a solid facing that is 3/4” x 1-1/4” vertical, how much could have improve the bowing resistance? Looking for a good source so as I go through designing custom cabinets, bookcases, shelving, etc., I have something of a source to use. I’m a civil engineering during the day, so the structural analysis side of me wants to know.

Thanks,

-- Rick - Spring, TX


9 replies so far

View oscorner's profile

oscorner

4564 posts in 3055 days


#1 posted 05-10-2007 04:08 AM

Are you talking about sandwiching plywood between two 2 X 4’s (I-beam type) construction?

-- Jesus is Lord!

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RickInTexas

45 posts in 2797 days


#2 posted 05-10-2007 04:23 AM

No, like using birch ply as a shelf in a cabinet, or plywood carcass construction of bookcase with the plywood laying flat.

-- Rick - Spring, TX

View Karson's profile

Karson

34911 posts in 3144 days


#3 posted 05-10-2007 05:33 AM

I’ve seen some articles on that condition. Also the relative strength of mdf and plywood and with and without face boards.

But I don’t remember where. There is a web site called Woodworking Magazine index you might check there for some hits.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View Hawgnutz's profile

Hawgnutz

526 posts in 2820 days


#4 posted 05-10-2007 07:11 AM

Seems I read an article in Popular Woodworking or some other woodworking magazine, that said that adding an edge to plywood would reduce the flexing and bow some 50-70 percent.

MLCSWoodworking.com has a tongue amd groove edge banding set (part # 1081) to put a solid wood edge on plywood.

Adding a strip of wood along the bottom will help strengthen it too.

If the price of the banding set seems a little high, you can wait until they go on sale. Just keep checking. What I like about MLCSwoodworking.com is that they offer FREE shipping.
I am sure you cab find some edge banding bits elsewhere, like Rockler or Woodcraft, but MLCS seems to have all the rest beat, pricewise, with excellent quality to boot!

Good luck and God bless!
Hawg

-- Saving barnwood from the scrapyards

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PanamaJack

4473 posts in 2821 days


#5 posted 05-10-2007 03:41 PM

In the Spring 2005 issue of Woodworking Magazine ( http://www.woodworking-magazine.com/magazines.asp ) There is an article about: “The Science of Shelving”. It tells about a set of rules or guide line to follow to not get sagging shelves. It has a graph showing 1/4” of deflection. Different spans and different widths & thicknesses of plywood with Particleboard core, MDF core, or veneer core, plus solid board shelving. It is very interesting. You cannot get this article off the net unfortunately.

Email me if you need any more information…I would not want to have a copyright violation held against me. :-) (Remembering is is for personal use only)

I bought the CD set, pretty interesting. Lot better storage than bulky mags…then just print what you need.

-- Carpe Lignum; Tornare Lignum (Seize the wood, to Turn the wood)

View Bill's profile

Bill

2579 posts in 2905 days


#6 posted 05-10-2007 06:30 PM

I thought I read somewhere that the span for unbanded plywood was 30-36”. It sounds like PJ has some better information on that.

I bought a set of the plywood banding bits from MLCSWoodworking and they work great. Easy to cut a groove into the plywood, and then cut a matching piece on the hard wood. I still need to practice the edging part, to have a consistent exposed band on each side. But, I do like the bits.

-- Bill, Turlock California, http://www.brookswoodworks.com

View Karson's profile

Karson

34911 posts in 3144 days


#7 posted 05-11-2007 04:31 AM

I’ve used the bits on the cradle/Glider that I made so that where I glued plywood to solid wood I’d have a better bond that just plywood edge. I sanded the edge flush and veneered over the top of the plywood and the solid wood.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

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Karson

34911 posts in 3144 days


#8 posted 05-11-2007 04:32 AM

PanamaJack. Yes the CD’s are great.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View Don's profile

Don

2600 posts in 2921 days


#9 posted 05-11-2007 05:33 AM

Quote RickInTexas: ”Is there any source that give how much you can free span say 3/4” plywood without is bowing under common loads?”

I’ve got just what you asked for.

THE SAGULATOR

-- CanuckDon "I just love small wooden boxes!" http://www.dpb-photos.com/

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