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Plywood thickness on edges of sheets

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Forum topic by garberfc posted 553 days ago 762 views 0 times favorited 24 replies Add to Favorites Watch
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garberfc

57 posts in 888 days


553 days ago

Topic tags/keywords: plywood thickness question

I’m sure most all users of hardwood plywood realize that the thickness of the material is slightly thinner on the edges. I just have a few questions about it…

In the past if the veneer at the edge was in perfect shape I wouldn’t worry about the thickness and would use the material as is. I liked to take advantage of the perfectly square factory corner.

When using the plywood for cases and sliding the edges into dadoes it’s noticeably tighter / looser based on the board being an edge piece or not. It’s usually not possible to drive a screw threw the opposite side of the dado.

I hope the following questions don’t seem too ridiculousness :-). It’s just the type of thing that keeps me awake at night…

Questions:
  1. Are all four edges thinner or just the long sides?
  2. Are the thin edges milled thinner or do the machines that are handling the boards crushing them? If crushing them, is there any chance of using moisture, steam… to bring the thickness back?
  3. Is the difference in thickness isolated to the veneer, the non-veneer portion or spread proportionally?
  4. On the loose dadoes, should I just use a little extra glue or attempt to make a shim?

Thanks in advance for your thoughts,
F


24 replies so far

View SamuraiSaw's profile

SamuraiSaw

450 posts in 598 days


#1 posted 553 days ago

I never use the factory edge of any sheet good. It is rough, usually damaged, and seldom “perfectly square”.

-- Artisan Woodworks of Texas.... www.awwtx.com

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Grandpa

3100 posts in 1309 days


#2 posted 553 days ago

No square corners either. Just luck if there is.

View waho6o9's profile

waho6o9

4840 posts in 1211 days


#3 posted 553 days ago

Rip the factory edge and use for back rails, etc.

View garberfc's profile

garberfc

57 posts in 888 days


#4 posted 553 days ago

What do you feel is the minimum number of inches to rip?

View SamuraiSaw's profile

SamuraiSaw

450 posts in 598 days


#5 posted 553 days ago

Back rails for base cabinets; 1 1/2” is a good size.

Back rails for upper cabinets; At least 2” but not more than 3”

-- Artisan Woodworks of Texas.... www.awwtx.com

View waho6o9's profile

waho6o9

4840 posts in 1211 days


#6 posted 553 days ago

+1 for SamuraiSaw

View joeyinsouthaustin's profile

joeyinsouthaustin

1246 posts in 706 days


#7 posted 553 days ago

I don’t find this to be true on the higher grade plys. i am using a d-3 maple and b-2 and dont have this problem. i routinely use a 3/8” cleanup, and this is euro cabs i am building … mostlt

-- Who is John Galt?

View teejk's profile

teejk

1208 posts in 1318 days


#8 posted 553 days ago

I think it all comes out of the factory at a uniform thickness. The edges just get beat-up in every stage of the distribution chain. For what they charge you would think they would treat the stuff like eggs but they don’t, I guess because we usually have no choice other than to “take it or leave it”. I’ve seen some sheets with bootmarks on them.

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SamuraiSaw

450 posts in 598 days


#9 posted 553 days ago

As joey pointed out, this isn’t nearly the issue with better grade sheet goods. The big box stuff is low price point, low grade plywood. Even with the better grade, I don’t rely on the squareness of the panel or the quality of the factory edge for a finished product.

-- Artisan Woodworks of Texas.... www.awwtx.com

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joeyinsouthaustin

1246 posts in 706 days


#10 posted 553 days ago

Samurai And to reenforce your point, even thought the better grade ply has a very consistent thickness, It should not be assumed to be straight, square, or clean (and rarely is) but the thickness is quite consistent, and the tolerances on the others much better. On chinese birch or BBox ply I would routinely take 3” to clean up, as my upper cab nailers are 2 1/2”.

-- Who is John Galt?

View SnowyRiver's profile

SnowyRiver

51451 posts in 2114 days


#11 posted 553 days ago

I agree that cabinet grade ply is much better in uniformity than the big box store construction plywood. If there are thin edges on cabinet ply, its due to the distribution chain as some have said. I always rip off the edge to be sure its square and even before using it. Most times it only takes 1/2 to an inch to clean it up.

-- Wayne - Plymouth MN

View Lumpyx's profile

Lumpyx

42 posts in 558 days


#12 posted 553 days ago

I work in a lumberyard and have never really noticed this before. Im gonna check it out when I go back in from my lunch break here in a bit. I would think it has something to do with how it’s stored. All of our units are banded tightly and sit on two or three 2×4 dryers so the forktruck can get under them. Maybe theres uneven pressure distribution on certain units depending on how they’re built and banded. That’s just a guess though.

-- "For long you live and high you fly, but only if you ride the tide."

View Monte Pittman's profile

Monte Pittman

13827 posts in 972 days


#13 posted 553 days ago

Never trust a lumber yard to cut anything square. That’s not important to them.

-- Mother Nature created it, I just assemble it. - It's not ability that we often lack, but the patience to use our ability

View Lumpyx's profile

Lumpyx

42 posts in 558 days


#14 posted 553 days ago

That’s not important to some. Alot of the guys I work with dont care at all but I try to cut every piece as if it was my own because I know how frustrating it is to have a board that’s not square.

-- "For long you live and high you fly, but only if you ride the tide."

View garberfc's profile

garberfc

57 posts in 888 days


#15 posted 553 days ago

@Lumpyx: The difference in thickness is generally < 1/32 of an inch. The difference when using a dado joint is having a snug fit and a joint where the board falls out!

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