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Wood movement with maple and cherry

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  • Wood movement with maple and cherry

    I'm building a video shelf with leftover cherry and maple boards. Need help with wood movement.

    All boards will be 5" wide. The left and right side (vertical) boards will be cherry. The shelves will be a.cherry or maple.

    I will use 2 pocket screws at the ends of all shelves to join the side boards.

    With the pocket screws spaced 4" apart will seasonal wood movement split the wood? Thanks in advance.
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  • #2

    Re: Wood movement with maple and cherry

    I don't think you'll have any problem.

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    • #3

      Re: Wood movement with maple and cherry

      Using a table published by Fine Woodworking a few years ago, you can predict a change in width of 0.01 inch for each percentage point change in moisture level of your board.

      As mentioned by Kayak Jim, you should be ok.

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      • #4

        Re: Wood movement with maple and cherry

        I would not be using pocket screws, I would router a housing about 5mm deep and sit the shelf in it, glue it, nail / screw it from the outside, a far more reliable joint.

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        • #5

          Re: Wood movement with maple and cherry

          You'll be fine on the wood movement. as the boards are in the same plane, meaning the fibres are moving the same way even though one is horizontal and one is vertical. wood is like a bunch of straws bound together when they have moisture they get fatter easier the taller, therefore, most of the movement is in the width of the board, not the length. where you have problems is when you have one piece attached in a different plane say your shelf was attached to the back the shelf would not get longer or shorter (at least not enough to matter) where the backboards that run vertically will get wider in humid conditions and thinner in dry conditions.
          I do agree with bkrits on the joint holding the shelf.
          Jerome
          Canada's South Coast

          Port Colborne On.
          Every loaf of bread is a tragic tale of grains that could've become whiskey.......but didn't....

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          • #6

            Re: Wood movement with maple and cherry

            To figure wood movement, look at the ends of your boards. The way the grain runs is the way way the wood will move with seasonal humidity changes. If it’s flat sawn wood (your grain runs more or less parallel to the width of the board) the board will shrink and grow in width. If it’s quarter sawn (the grain is more or less parallel to the thickness of your board) it will grown and shrink in thickness. When you are building something, you align your material so everything is going to move in the same direction, or make allowances that are not going to tear your piece apart over time. When I build a case with a back, I leave a 3/32” space behind any shelves that are glued into the case. The back of the case is glued into a rabbet and then a few 3/32” spacers are glued to the back of the shelves and the back is screw fastened through to those. I have never had a problem with any of my furniture.

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            • #7

              Re: Wood movement with maple and cherry

              Thanks everyone for your feedback. I really appreciate it.

              I've decided to cut slots in the cherry vertical panels with a dado set.

              Are the screws really necessary? Is the glue joint alone not strong enough? I was planning on using clamps for the glue up.

              I have flatsawn lumber. For the wood movement, the coefficients are 0.00126" and 0.00165" for cherry and maple respectively. So for 5" wide boards and a 5% MC change in the house, the wood movement is 0.0315" and 0.0413" for cherry and maple. The difference is 0.009" or roughly the thickness of 2 sheets of paper.

              The vertical cherry boards will move at the same rate as the cherry shelves. The maple shelves will move slightly more or wider than the cherry vertical boards.

              I hope I'm on the right track here. Comments?

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              • #8

                Re: Wood movement with maple and cherry

                Originally posted by Nelson in Markham View Post
                Thanks everyone for your feedback. I really appreciate it.

                I've decided to cut slots in the cherry vertical panels with a dado set.

                Are the screws really necessary? Is the glue joint alone not strong enough? I was planning on using clamps for the glue up.

                I have flatsawn lumber. For the wood movement, the coefficients are 0.00126" and 0.00165" for cherry and maple respectively. So for 5" wide boards and a 5% MC change in the house, the wood movement is 0.0315" and 0.0413" for cherry and maple. The difference is 0.009" or roughly the thickness of 2 sheets of paper.

                The vertical cherry boards will move at the same rate as the cherry shelves. The maple shelves will move slightly more or wider than the cherry vertical boards.

                I hope I'm on the right track here. Comments?
                Just an idea: have you considered sliding dovetails? This would eliminate any concern with moisture variations.

                Comment


                • #9

                  Re: Wood movement with maple and cherry

                  The difference in movement between the two woods is negligible. Put it out of your mind. You don’t have to jump through hoops, or overthink this. In order for the difference to amount to anything, one side of your case is going to have to be immersed in water while the shelf is under a heat lamp.
                  VincentC, Wally in Calgary and Jerome like this.

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