# "Factory" edge on plywood: True and square? Or not?



## DadoDog (Mar 7, 2015)

Here's a question for the experienced cabinetmakers out there, and for those knowledgeable about plywood. Specifically, my question has to do with the so-called "factory" edge on plywood. I know quality may vary among different manufacturers, but during a recent cabinet-making project I noticed that butt joints weren't fitting tight and square, and not just because of the relative roughness of the cut. So, upon checking several edges with my Starrett combo square, I found that they were slightly beveled!! And this was cabinet grade plywood!

Seriously now, some manufacturers cut their ply with out-of-square saws? So instead of assuming edges are true 90 degrees to the surface, I now will check for squareness.

I'm wondering if my experience is unusual. Also, I'm wondering if good cabinetmakers trim off the factory edges before cutting material to size. And can I at least trust that the edges are straight, and that on full sheets the corners are accurately squared?


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## woodbutcherbynight (Oct 21, 2011)

I assume all lumber needs to be trued, plywood being no exception. As you pointed out even good grade plywood does not mean it is square. *Bearpaw* pointed this out to me years ago and it has helped me avoid many mistakes by just cutting it myself 1st.


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## therealSteveN (Oct 29, 2016)

Thousands of sheets of plywood later, and I really can't say it's perfect, but what is? I have never had an instance where a plywood edge wouldn't fit right off the sheet though, so for me it's never been an issue. I guess I can't think of a time where I butt joined plywood to itself, or anything else. I always entrap it into a frame of some sort, or just use it straight up as sheathing, or a panel of just ply.


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## Loren (May 30, 2008)

Factories probably size it to width on giant saws 
with blades set 48" apart. The panels are
probably stacked quite thick as well. The saw
blades may warp or deflect in the cut when they
heat up. If you ever make a cut with a 12" 
miter saw where you're trimming off a thickness
less than the width of the blade, check it for
square after because the blade can deflect 
from cutting on only one side. In many situations
such cuts are within acceptable tolerances but
it's an interesting thing to note.

The factory edge is considered by pros to be 
something you cut off. It's there to protect the
rest of the sheet, not to be a reference edge.

You may not be aware that making finish size
cuts in a full sheet of plywood is not a good idea
if you're working to fine tolerances. Cutting
a sheet down releases stresses, just as with 
solid wood. Sometimes the long edges move
out of straight (pretty common) even if you 
have something like a track saw or slider that
cuts really straight. Out-of-straight edges are
not usually a problem in face frame work but
in frameless cabinets they can be bad news. 
This is one reason melamine is preferred for
frameless construction. It can move but it's
a lot less prone to it. Even if long edges do
move on melamine, it probably won't be enough
to produce a significant reject rate when run
through an edgebander.


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## woodbutcherbynight (Oct 21, 2011)

> Thousands of sheets of plywood later, and I really can t say it s perfect, but what is? I have never had an instance where a plywood edge wouldn t fit right off the sheet though, so for me it s never been an issue. I guess I can t think of a time where I butt joined plywood to itself, or anything else. I always entrap it into a frame of some sort, or just use it straight up as sheathing, or a panel of just ply.
> 
> - therealSteveN


I hear ya. I usually edge band the stuff so I have a solid wood exposed surface to finish rather than seeing layers of ply.


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## clin (Sep 3, 2015)

I never "trust" the edge of sheet goods and will generally always trim it off.


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## AlaskaGuy (Jan 29, 2012)

It can be and it can not be. It comes both ways. Ever wonder why melamine is 49×97? Or why pre-finished plywood is 48 1/2 by 96 1/2? It's so you can straighten and square up the sheets. These are the sizes you get if you buy sheet good from a dealer who caters to the cabinet maker. We ain't talking the Big Box stores.


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## RichT (Oct 14, 2016)

Not square in my experience. I'd never trust it to be.


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## therealSteveN (Oct 29, 2016)

> If you ever make a cut with a 12"
> miter saw where you re trimming off a thickness
> less than the width of the blade, check it for
> square after because the blade can deflect
> ...


Gee Alaska, and all this time I just though more for your $$$Money$$$ But I will give you that the rough handling they get at ANY place sheet goods are sold, the edges of the non ply, stuff like MDF, Melamine, etc, are very friable, and getting whacked around does beat them up, so the extra is so, yes, you can get a 4×8 sheet from them. Or if you are actually the one picking your own stock you can pass on the top 5 or 6 sheets on the stack, as being junk. That is why I always suggest you bring a friend or co-worker to pick ply. My history is I move 10 sheets to get 4, and not being a slug I always put what I pull off, back on the pile.


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## Loren (May 30, 2008)

I see nothing about what you wrote that makes
me inclined to take your claims of vast 
experience seriously. Good try though.


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## therealSteveN (Oct 29, 2016)

Don't much care what you think about me, but answer me then, do any of these guys have any chops?

"Furthermore I have never seen it referenced, used or implied on any of the TOH, Tommy, Scott, WoodSmith, or other shows I have seen, and those guys certainly use plywood right there, you can watch them saw it up."

For that matter can you produce a written explanation done by a well known woodworking writer saying you "HAD TO" waste the factory edge of a piece of plywood? I'll be shocked if you can.

My only "agenda" is telling people as best I can what has worked for me, and to push safe woodworking practices as often as I can. There are MANY who give uninformed information, and it confuses the noobs, and makes this woodworking stuff more dangerous, and injurious than it need to be.


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## 000 (Dec 9, 2015)

Back in the day you could depend on square sheets. That's not the case these days though.
I trim everything. Also a cabinet builder for 35 - 40 years!

SteveN, You keep doing what works for you.

Here is a pic of cabinet grade material:
Does this look square to you?


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## builtinbkyn (Oct 29, 2015)

Well I'll not speak for Loren as I know he's perfectly capable of that himself. But I will say he's always given sound advice and has always been cordial. I think he knows his stuff and has exhibited it here from time to time. That is good enough for me.

As to the idea of removing the factory edge on sheet goods - I do it too. As has been mentioned, wood is too valuable to waste and relying on a factory cut edge from China isn't where I'd lay my trust. Sheet goods, even premium sheet goods, are mass produced, mishandled and not stored properly. If there's going to be an issue with sheet goods, it will more than likely be at the edge where moisture and the aforementioned will effect it. So I make my cut to provide a clean, fuzz-free edge which I know to be true, and use that as reference moving forward with a project.


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## Loren (May 30, 2008)

I cut and banded the panels for a murphy bed
last week. Two or three of them went a little 
banana-shaped on the edges after the first cuts 
using a Mafell PPS, which cuts quite straight. 
I let them move overnight and then recut the 
curved edges before ripping to final width.

I use a Hess Mobil 2500 edgebanding press that
requires that edges be quite straight. The longer
the edge, the straighter it needs to be to make
a glueline within the tolerances I want.

Since I've observed this phenomena and have to
pay attention to it because of the limitations of
my bander, I can say for certain that it's a thing
that occurs with plywood.

I don't really watch woodworking TV shows so I
can't comment on whether or not these guys are
familiar with required tolerances for using 
edgebanders like mine.


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## therealSteveN (Oct 29, 2016)

> - Jbay


Funniest plywood edge I have ever seen. Are you sure that is the correct pic to post for your argument of bad plywood edges? Kinda looks like a 2×4.

Loren, I am giving up, but I do note with some satisfaction that my professional experience is of absolutely no concern to me anymore. The reason is I am not competing for any work here.

I do note though you have steered absolutely clear of my question as to why we haven't seen the "cutting off of the badddddd edge" showcased in numerous woodworking magazines, and on every woodworking TV show ever made. I mean you make it sound so sinister, that killer plywood. Hey, it's a product made from mostly natural stuff, you got a complaint with how it works, you need to have a talk with Mother Nature about it.

Wow those tools, talk about something that is hard to believe, sheesh, you got me edged there. Have a great day.


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## 000 (Dec 9, 2015)

> Funniest plywood edge I have ever seen. Are you sure that is the correct pic to post for your argument of bad plywood edges?
> 
> - therealSteveN


I guess, if your calling this edge good, you must really be a craftsman. Not a good one though…LOL


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## builtinbkyn (Oct 29, 2015)

> - Jbay
> 
> Loren, I am giving up, but I do note with some satisfaction that my professional experience is of absolutely no concern to me anymore. The reason is I am not competing for any work here.
> 
> - therealSteveN


Are you a nurse, as your LJ bio states or a professional cabinet maker? Why not post some of your work? It would lend more credibility to your argument. Also, why would you use TV and YT videos as authoritative reference? Just asking.


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## MrRon (Jul 9, 2009)

I have never been concerned with perfectly straight plywood edges nor did it ever occur to me to check for squareness. My use of plywood does not require me to butt sheets together except for construction purposes as sub flooring. When I do use plywood for a woodworking project, it is usually in small sizes as in cabinet making. Working with an oversize piece cut from a full sheet, I will trim it down to the finished size, depending on my machine accuracy to give me the squareness I need. I have noticed "parallelogram" sheets from the big box stores, but it doesn't affect my final useage.


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## skatefriday (May 5, 2014)

I always rough cut my plywood sheets and never reference against a factory edge. Nor do I ever join a factory edge.


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## Tony_S (Dec 16, 2009)

> Absolute thousands of sheets of ply
> - therealSteveN


That's it?

I've had a bare minimum of 100,000 sheets of rough and veneered ply of every description go through the shop in the last 25 years. Probably closer to 150,000. I buy it by the lift or half lift, not the sheet. 1/4" through 1". Veneer core, particle core, MDF core, 4×8, 4×10, 5×10, CDX, A1, A4, B1, B4, Architectural grade, custom press's. All domestic, from suppliers that deal with mills all over North America..blah blah.
Vertical panel saw's, sliding panel saws, a beam saw, a CNC. Blah blah..

Don't care what the guy on TV says, or doesn't say, there isn't a soul in my shop that would trust a factory edge.

As for you disagreeing about plywood not being capable of holding stresses, bowing, warping, twisting, cupping, shrinking or swelling. Again, you're mistaken. Plywood is not inert. It 'typically' doesn't happen to a degree that it's a problem, and most often not even noticeable, but It can and does happen.

And you need new glasses if you think that out of square plywood edge that Jbay posted looks like a 2×4.


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## AlaskaGuy (Jan 29, 2012)

> If you ever make a cut with a 12"
> miter saw where you re trimming off a thickness
> less than the width of the blade, check it for
> square after because the blade can deflect
> ...


Lol, I guess we have a new comedian on the forum.


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## RichT (Oct 14, 2016)

Square or not, I've never purchased a sheet of plywood that had the clean edge I get from my saw. I don't consider cutting 1/8" over and trimming the factory edge wasteful, and it ensures me square corners and clean edges.


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## RichT (Oct 14, 2016)

> Lol, I guess we have a new comedian on the forum.
> 
> - AlaskaGuy


I'm not even reading his nonsense, AG. Another guy with 40 years of experience cutting "thousands" of sheets of plywood, and his only project looks like a reject from Flea Market Flip. I'd actually think more highly of the guy if he hadn't posted any projects.


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## AlaskaGuy (Jan 29, 2012)

> Lol, I guess we have a new comedian on the forum.
> 
> - AlaskaGuy
> 
> ...


I've built quite a bit of "stuff" over the years using a variety of sheet good. Majority of it would be Plywood and Melamine. You won't find a single factory edge in any of it.


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## AlaskaGuy (Jan 29, 2012)

I have read over on the WoodWeb's professional cabinet making forum the problems they have with their automatic edge banders when the edges being banded get more that 2 degrees out of square.

The is one reason I bought I bought a sliding table/panel saw. I always do always do a " dust cut" on the edge and an end before I start cutting parts. There is nothing like referencing of a true straight square edge. Especially if your doing framless cabinets.


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