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Thread: tearout on plywood

  1. #1
    Join Date
    Jan 2015
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    tearout on plywood

    this might seem like a silly question,,,but I just bought some dado blades and was planning on dadoing some shelves across plywood,,and this is my first attempt at it and it splintered really bad,,,the blades I have are not cheap,,i bought them from amazon and they had a good rating,,and I paid 90.00 for them,,,but the crosscut across plwood was terrible,,so I tried using a palm router and the cut was better but it seemed like a lot of effort on the router,,,can anyone help me or tell me what I was dong wrong,,,thank you

  2. #2
    Join Date
    Mar 2019
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    Los Angeles, California
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    The veneer is thin and unsupported. Do any or all of these:

    Score the projected cut with a knife or razor blade.. Heck, make a knife wall if you want.

    Tape over the area of the projected cut with masking tape.
    Regards,

    Tom

  3. #3
    Join Date
    Aug 2019
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    USVI
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    127
    Make a zero clearance insert for your saw. I also like Tom’s advice using tape and or pre scoring with a razor.

  4. #4
    If it is a nice piece of furniture I would opt for the painters tape and zero clearance insert method. Regular masking tape works better than painters tape, but it is rare these days. After making the cuts be sure to peel the tape off toward the cut edge so you don't lift any loose fibers.
    Lee Schierer
    USNA- '71
    Captain USNR(Ret)

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  5. #5
    Join Date
    Mar 2003
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    I'm with Lee...use multiple techniques to help mitigate risk of splintered veneer edges.

    What you're experiencing is also related to why some dado sets are better for veneered goods than others. It has to do with how the outside blades' teeth are designed. The higher end setups have a very steep and sharp angle and also tend to project a hair more than the chippers. While that leaves a noticeable mark at the bottom of a groove, rabbit or dado, it's what cleanly slices the veneer before the rest of the tooth geometry comes crashing down.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
    Join Date
    Feb 2014
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    Suffolk, Va.
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    Slow feed rate of the material is helpful. Make a very light pass taking off a minimum material then a final pass to full depth. All the other suggestions are good.
    Michael Dilday
    Suffolk, Va.

  7. #7
    Join Date
    Nov 2003
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    Central North Carolina
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    I agree with everyone's suggestions, but would like to know more about your specific dado blade and the type/kind/thickness and number of layers of the plywood that you are cutting.

    I make quite a few boxes with box jointed corners in Baltic Birch plywood and I don't have problems with splintered edges, but most of the time I'm using the Freud SBOX8 blade set and a zero clearance insert. I use a Freud Dial-A-Width dado blade for larger box joints and they aren't quite as smooth on the bottom of the cut, but the sides are just as clean.

    Charley
    Attached Images Attached Images

  8. #8
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    Nov 2009
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    Alaska
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    I've had a few different dado sets. They do not all work as advertised, despite their price point. I have been using an Infinity Dadonator the past few years, and there is no tear out whatsoever. Nice flat dados too. I make all kinds of shelving units, and I often use that cheap crap you find at the big box stores. There's little point in wasting a zero clearance insert, unless you plan to only cut dado's of one size.

  9. #9
    If you have a good sharpening service nearby it might help to have them sharpened, even if they are new.

    I did that with mine and they came back much sharper than they were from the factory.

  10. #10
    Quote Originally Posted by Charles Lent View Post
    I agree with everyone's suggestions, but would like to know more about your specific dado blade and the type/kind/thickness and number of layers of the plywood that you are cutting.

    I make quite a few boxes with box jointed corners in Baltic Birch plywood and I don't have problems with splintered edges, but most of the time I'm using the Freud SBOX8 blade set and a zero clearance insert. I use a Freud Dial-A-Width dado blade for larger box joints and they aren't quite as smooth on the bottom of the cut, but the sides are just as clean.

    Charley
    Those are beautiful boxes Charley!

  11. #11
    Jeff,
    You may want to try taking an initial light cut, maybe a 1/16" deep or so. This should be far less likely to tear out, and then you can proceed to full depth. Keep track of the depth adjustments as you go through your parts by how many turns of the crank arrived at the proper depth.

    regards,
    Chris Giles

  12. #12
    Join Date
    Mar 2008
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    Between No Where & No Place ,WA
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    Speaking from experience, tape, scoring, and a zero clearance insert (ZCI) will work. learned this one the hard way.

    I made several dado ZCI inserts for my old Uni-saw from 1/2" plyw'd and labeled each one as to what chippers were utilized. As I now run a SawStop, ICS with a Colliflower replaceable insert, I still do the same. http://www.colliflower-zci.com/

    Resharpening is a good idea. Just be sure to tell the sharpener to grind the blades and chippers to the same diameter for flat bottoms. Another lesson learned the hard way.

    As always, the dado cut quality will depend upon the quality of the work material.

    Cha's Lent: nice looking boxes.

  13. #13
    Join Date
    Mar 2003
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    I wonder what plywood you are cutting? If it is from a big box store, the show layer is so thin that it shatters often on crosscutting.

    How does it cut on Baltic birch, or solid hardwood, like oak?
    Rick Potter

    DIY journeyman,
    FWW wannabe.
    AKA Village Idiot.

  14. #14
    Join Date
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    Quote Originally Posted by Rick Potter View Post
    I wonder what plywood you are cutting? If it is from a big box store, the show layer is so thin that it shatters often on crosscutting.

    How does it cut on Baltic birch, or solid hardwood, like oak?

    Rick beat me to it. Before we blame the dado stack, let's look at what we are cutting. High quality, thickly veneered hardwood plywood and/or plywood with many thin layers will do better than soft lumber core plys with tissue thin veneer. I use a scoring line for veneers and even on some tearout prone hardwoods. I will also use a scoring cut with a marking knife or razor for a critical cut in any material. Tape can sometimes tear loose the fibers that it just saved from tearout so test some cuts on some scrap of the material you want to use. If the tape pulls up fibers, skip the tape and just slice a scoring line.
    "What kind of chump do you take me for?"
    "First class."

  15. #15
    Join Date
    Nov 2009
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    Peoria, IL
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    1,658
    A $90 dado set is a cheap set in my opinion.

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