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  • Pin tear out on dovetail jig

    I was cutting some drawers on my PC dovetail jig and was repeatedly having tear out problems with the pins (the vertical piece). I was using half inch baltic birch ply. I do a few things to try and prevent this but I still had some problems yesterday. I make a scoring pass before I start to cut the pins and I move the router from right to left. The scoring helps somewhat but I still had too many instances. I adjusted the speed of my router and it seemed to me that the higher the speed the better the results. I can't imagine the bit being dull. I've only used it a couple of times. Has anyone else had this problem?

  • #2
    Re: Pin tear out on dovetail jig

    I had that problem with my Akeda. What I do now as a matter of course is to put in a backer board. It wasn't my idea...you can thank Norm!! Apparently, using a backer board is required for any dovetail jig. Just use any scrap wood that's the same thickness or more. I'll generally go for a thicker piece if I have one.
    I put it all back together better than before. There\'s lots of leftover parts.

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    • #3
      Re: Pin tear out on dovetail jig

      Originally posted by VASandy View Post
      I had that problem with my Akeda. What I do now as a matter of course is to put in a backer board. It wasn't my idea...you can thank Norm!! Apparently, using a backer board is required for any dovetail jig. Just use any scrap wood that's the same thickness or more. I'll generally go for a thicker piece if I have one.
      Just out of curiosity, why does the backer board have to be as thick, or more, than the work piece? I use 1/4" hardboard / plywood scraps and it works fine.

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      • #4
        Re: Pin tear out on dovetail jig

        Just to clarify....I'm having tear out on the piece of the board that is closest to you, not the back side. It's not blowing out in the back because I have the tail piece behind it. As I move the bit from right to left it tears out the wood on the left side of the pin. Since it's plywood it typically pulls off the top ply and pulls off anywhere from a 1/2" to 1" strip of it.

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        • #5
          Re: Pin tear out on dovetail jig

          Originally posted by rnt80 View Post
          Just to clarify....I'm having tear out on the piece of the board that is closest to you, not the back side. It's not blowing out in the back because I have the tail piece behind it. As I move the bit from right to left it tears out the wood on the left side of the pin. Since it's plywood it typically pulls off the top ply and pulls off anywhere from a 1/2" to 1" strip of it.
          You shouldn't get tearout on the backside because as you've said the tail piece is already acting as a backup to prevent tearout on that side, but you should sandwich the pin board with another scrap piece on the front side of the board. This should be enough supprt to prevent the veneer from popping off. Just be careful though because even after successfully cutting dovetails in birch ply you can have problems with veneers popping off during assembly.
          Wider spaced tails and pins can help with that,,,
          Cheers! - Jim
          -------------
          All truth passes through three stages: First it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. - Schopenhauer

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