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Thread: Sawing through birch plywood, don't want to damage veneer

  1. #1

    Question Sawing through birch plywood, don't want to damage veneer

    Hi all,

    I am working on building a toolbox out of birch plywood (23/32). I'm afraid that sawing it (hand saw) will mess up the pretty veneer on the edges. I've heard that this can be an issue. How should I combat this, or does it not matter?

    Thanks,

    Rob

  2. #2
    Put a strip of tape on the bottom side of a scrap and see if that helps.

  3. #3
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    Are you really talking hand saw, or do you mean circular saw? I read somewhere that pre-scoring the exit side with a razor knife was a good way to help prevent tearout. I tried this once and did not get the pre-scoring exactly right. I think its a technique with merit but it requires very careful measurement on both sides to get the lines correct. Otherwise, I had luck with a zero clearance insert on my table saw, and a similar zero clearance plate for my circular saw (a 1/4" thick piece of masonite double back taped to the bottom of the circular saw plate. I think the correct answer for the power tool route is a combination of zero clearnce adapter and a saw blade intended for veneer plywood cutting. For manual sawing I don't know but you might be able to have a backer piece to help support the cut edge but of course thats just more material to cut through as well.

  4. #4
    Yup, I'm really talking hand saw! I want this project to be able to be completed by people who have only a hand saw, so I'm doing it with a hand saw myself. I agree about the scoring- it does sound tricky. I can post some results of a test cut today or tomorrow.
    Last edited by Rob Schwartz; 03-13-2014 at 8:22 PM.

  5. #5
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    You might want to post this on the neander forum, but in my opinion you are going to get significant tear out, particularly if you use BORG plywood, even with a very sharp hand saw. Taping the bottom side with masking tape (painters tape is not sticky enough) might reduce the chipping of the veneer. When you remove the tape be sure to peel it toward the cut line. Pulling it away from the cut line will lift any loose areas.

    A Japanese push pull type saw might give you less tear out.
    Lee Schierer
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  6. #6
    Okay, so I tested out a hand saw on a scrap piece and the results aren't pretty, to say the least. The top looks permissible, but the veneer is messed up and the bottom tore out, even with tape. So what should I do if I am going to use a circular saw instead?

    By the way, thank you all for your helpful suggestions. I'm hoping that all of this discussion pays off before I make the actual project.

  7. #7
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    You might want to take the implied advice above and consider a higher quality plywood

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    I would point out that the old-timers who were doing this entirely with hand tools were not working with plywood. That said, I would use a good straightedge and a sharp marking knife to score BOTH edges of the cut before I tackled it with the saw. It would also be worthwhile to use a saw with fine, sharp teeth.

  9. #9
    Mike, I would go with something higher quality, but I want to keep the price down. Thank you for the suggestion, though.

    Ron, does that apply to circular saw blades also? Would you recommend using a circular saw blade with fine, sharp teeth?

    Thanks,

    Rob

  10. #10
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    If you go with a circular saw, consider getting a quality blade for it specifically ground for plywood such as the Forrest Hi-AT.

  11. #11
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    A circular saw with a blade that is designed to cut plywood (many fine teeth) and a zero clearance insert type saw shoe is how I do this. My saw shoes are made from 1/8 - 1/4" Lexan the size of the whole foot on the circular saw, and I bolt these in place with two flat head bolts, one in the front and one in the rear of the saw foot up through the foot from the bottom and countersinking the holes in the Lexan enough to keep the heads of the bolts recessed and the bottom of the lexan flat and smooth. I plunge cut a blade slot through the Lexan and then mark the area where the Lexan interferes with the blade guard function. Then I remove the Lexan and cut out this marked area, being careful not to remove the area ahead of where the guard moves. This area is where the blade teeth rise up through the Lexan, and where this Lexan shoe prevents the blade teeth from lifting the wood fibers on each side of the saw cut. Then re-attach the Lexan shoe to the saw foot using the flat head bolts and make certain that the blade guard can operate correctly. You have now completed the build and installation of this zero clearance insert. When this blade and zero clearance shoe are mounted on your circular saw you should be able to cut Baltic Birch or other plywood and have very little, if any, tear out, but the area where the teeth rise up at the leading edge of the cut must be kept close to the blade. If it wears or you use a different blade will need to make a replacement shoe.

    Charley

  12. #12
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    Quote Originally Posted by Ron Kellison View Post
    I would point out that the old-timers who were doing this entirely with hand tools were not working with plywood. That said, I would use a good straightedge and a sharp marking knife to score BOTH edges of the cut before I tackled it with the saw. It would also be worthwhile to use a saw with fine, sharp teeth.
    Ron beat me to it.
    This is the way I was taught.

    Score all the way around.
    I use TWO PARALLEL LINES and saw between them.

    The first knife pass can be very light, with a sharp blade.
    I recommend clamping the straight edge used to the sheet goods.

    Once you have established a line, you can score quite deep.

    I use a simple crosscut saw to break down smaller pieces, suitable to make a tool box.


    I've taken to a method where you remove all but the outermost two plies,
    and form a sort of rabbet on the end. Once glued and dried, the thin ply can
    chamfered at the edge to hide the joint.

    This not only makes alignment easier during the glue up, it also makes for a tight joint.
    I would not leave this as the only structural component of a toolbox.

    Corner blocks, gussets or some kind of internal webframe should be considered as
    a complement to the glue. rabbet_joint_plywood.jpg
    Last edited by Jim Matthews; 03-14-2014 at 8:07 AM. Reason: illustration

  13. #13
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    I have a Freud 10" blade that is labeled "melamine both sides". Wouldn't be surprised if they made a 7 1/4 for that too.

    Rick Potter

  14. #14
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    Amazon has 7" plywood blades for circular saws. They cost less than $10. IIRC, they work.

    I haven't used one in 30 years. I bet you can buy one at the BORG.

  15. #15
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    Using a track saw (DeWalt, Festool, Grizzly, etc.) can achieve very clean, sharp cuts in plywood. I have the Festool track system and I get exceptionally clean cuts in plywood but it is well-designed to do this...but it is pricey. However, you can still do it with a regular circular saw AND a good sharp, high-tooth blade designed for crosscutting plywood. You simply make up your own track/guide with a couple pieces of plywood and you use your saw to trim your shop-made track/guide to give it zero-clearance.
    Wood: a fickle medium....

    Did you know SMC is user supported? Please help.

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