Reply by therealSteveN

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

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3399 posts in 1030 days

#1 posted 03-30-2018 05:01 PM

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.

My saw seems to cut across the entire width of the blade, unless I am trying that trim off a “lil bit” stuff, then you certainly can get deflection. I would suggest you make sure you are always cutting a full width of the blade, it’s not hard to do, just rough your pieces to 1” over actual

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.

I had been a professional cabinet maker for over 40 years, and I , nor any of my cronies wasted expensive plywood, so I have no professional reference to what you are saying here. 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. So in essence I’m calling BS on this.

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.

See my comment above.

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.

Huh, gonna hold my fingers back here about cuts creating “stresses” on sheet goods. It tells me you have little understanding of wood movement. So NO, NOT just like solid wood, it is actually for this reason it is used in cabinets.

Out-of-straight edges are
not usually a problem in face frame work but
in frameless cabinets they can be bad news.

Finally you say something I agree with, so how can you explain what I know to be true. Absolute thousands of sheets of ply, using the edges as I got them, and I haven’t experienced this problem you are talking about. I can only imagine your saw isn’t cutting straight lines, and is out of square, so your problem is self created?

I will suggest to anyone NOT finding square cuts on plywood full sheets, that they make sure they are tight to the fence ALL the way through the cut. Secondly, and most importantly, they are certain their TS is set up to make a square cut. What a person will see in a BIG picture way is not square cuts, and they will appear much more pronounced on full sheets of plywood for 2 reasons.

1) You have a much wider, longer sight picture to look at the final cut, than if you are cutting up smaller pieces of solid wood, where it just becomes apparent on attempt to assemble, sometimes looking at a smaller piece you may not see the problem of an out of square piece, on assembly you still may not “see” it, but you will have a poor fit.

2) Most individuals are ill equipped to pick up, and handle a 4×8’ sheet of plywood, and easily slide it down the saw, tight to the fence. For them a track saw is advisable, and if they don’t take time to set it properly, they will/can cut out of square/rectangular cuts. Now if you can’t make true cuts on a new sheet, yes then you may have to lose some of your sheet goods, as you say you do.

- Loren

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. :-)

-- Think safe, be safe

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