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Birch Plywood Separating when cutting

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  • Birch Plywood Separating when cutting

    Hi, I'm cutting 1/2" sanded birch plywood 4' x 8', and the last 3 sheets have separated while carving them to .3" depth causing my bits to break and ruin the board. Did I just get bad plywood? is there a better wood? Am I carving too deep, wrong tool? speed? Any advice would be greatly appreciated.

    Also, the primary vaccuum on my black box is not working. Any idea what the problem may be? Thanks again!
  • #2

    What tooling are you using for these cuts? Speeds, feeds? While you certainly could have plywood that is "less than worthy", the nature of the product with a thin veneer on top takes care to cut cleanly. But if you are actually breaking tooling, there may be more to this than just the material. Please provide some more information so folks can help guide you to a solution.
    Jim Becker

    SR-44 (2018), 1.7kw spindle, Performance Premium, USB, Keypad, T-Slot table (y-axis configuration), WinCNC, VCarve Pro upgraded to Aspire

    Non CNC stuff...

    Festool "a good collection"
    Stubby - lathe
    Oneida Cyclone

    Retired from full time work in the telecom industry 9/2017
    Occasional commission work for others, but mostly for trunks/signage/guitars
    Located Bucks County PA


    • #3

      I'm carving with a v-bit .3 depth at about 14000 on an 1/2" piece of plywood. That's when I first noticed the separating of the plywood. I tried cutting at a lesser depth of .2 and had the same issue. Once the plywood is separated, the board is useless. The vbit isn't breaking, it's the 1/8" compression bit that breaks when it gets to the portion of the plywood that has separated. Hope this makes sense. Thanks again. Look forward to your advice.


      • #4

        The separating board is just a bad batch. I have a feeling we may see more of this with the wood shortages and people trying to cut corners to produce more product quickly and/or cheaply.

        Is there a reason you a using an 1/8" compression versus a 1/4, 3/8 +? I use an 1/8" for cutting out stuff on occasion depending on the geometry needed, but you have to slow way down to use one without breaking the bit. I don't run mine more than .10" deep at a time around 100ipm @16k. If I was making the same cut with a 3/8 compression I would run in the 400ipm+ range at 18k and full depth. I know some of the guys with Cobras run 500+ full depth depending on hold down.
        4'x8' Stinger IV w/ 4.2 hp spindle and 4 tool ATC
        Mister system
        Phenolic Vac table
        Hurricane Vac
        Vcarve Pro 10

        Catholic school IT director, wannabe woodworker, Krav Maga instructor, and CNC enthusiast


        • #5

          Just finished a project with 3/4 birch same problem on plys separating had to glue the parts I cut out back together some had voids on a layer 1 foot by 3 feet. Hope qc improves this in the future.
          SR44 StingerII
          3.5hp Milwaukee router
          ftc option
          laser pointer
          t slot bed
          Vectric 10.5


          • #6

            if you are talking about import birch don't expect things to get better until sometime next year, mills in vietnam and indonesia are now talking allocation as they social disctance their workforces and cut back on production...
            Joe Alcathie
            Stinger II 4x4
            Aspire 3.5


            • #7

              We have also started using import ply as the price and availability has gotten crazy. On the 3/4" ply, it appears that there is a layer of coconut husk in the mix. It tears bit up super fast. I am only getting about 20 sheets per bit and then they start chipping the veneer. Costing us all money.
              Existing:-2014 Cobra 5x10 ATC w/ 10 hp spindle, Mozaik, 25 hp Becker High Vacuum Pump, 5 HP Oneida DC-Central Texas
              New:-2014 Cobra 5x12 ATC w/ 10 hp spindle, pop up pins, phenolic top, lathe, vacuum relief valve, mister system, 25 HP Blower.