What's a quick but strong Butt Join?

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  • radhak
    Veteran Member
    • Apr 2006
    • 3058
    • Miramar, FL
    • Right Tilt 3HP Unisaw

    What's a quick but strong Butt Join?

    I want to attach two 6" wide boards to a 2" square post, essentially butt-joints for the 'aprons'. (see pic below)

    This will be for an elevated garden bed in the yard, so nothing fancy, but I can't have it fall apart too soon. I don't want to go cutting dadoes for this.
    I thought pocket screws, but will they stand the weight of 12 cu.ft of soil?

    Maybe I could add a tiny supporting bracket below each apron end, and that should be enough reinforcement? Or should I add a crossbar on the inside that I can attach to the post with screws?


    Click image for larger version

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    It is the mark of an educated mind to be able to entertain a thought without accepting it.
    - Aristotle
  • Jim Frye
    Veteran Member
    • Dec 2002
    • 1051
    • Maumee, OH, USA.
    • Ryobi BT3000 & BT3100

    #2
    1. Multiple biscuits and waterproof glue.
    2. Counter bored stainless steel screws through the outside of the posts into the ends of the sides and plug the counterbores.
    3. Small square blocks glued and screwed to the side boards and the legs.
    Jim Frye
    The Nut in the Cellar.
    ”Sawdust Is Man Glitter”

    Comment

    • cwsmith
      Veteran Member
      • Dec 2005
      • 2737
      • NY Southern Tier, USA.
      • BT3100-1

      #3
      Biscuits are okay and certainly the fastest IF you have a biscuit joiner, but I think dowels would be stronger. For years I've used dowels as they were often used in commercial tables for the 'skirts' as you have sketched.

      A few years ago I bought a biscuit joiner and I really like it for edge-joining boards to make larger table and bench tops. I don't know about end grain though, just seems a weaker glue surface. For that application I would consider mortise and tenon, but it is by no means quick!

      CWS
      Think it Through Before You Do!

      Comment

      • mpc
        Senior Member
        • Feb 2005
        • 979
        • Cypress, CA, USA.
        • BT3000 orig 13amp model

        #4
        If the planks can be made from glue-ups, consider face-gluing two panels to make one thick piece. Before gluing them run a pair of grooves in each one, on the faces that will get glued together. That way you'll end up with two channels end-to-end and can use two long threaded rods to tie into the posts at each end. Drill counter bore holes in each post for washers+nuts, then plug the holes. Somewhat similar in concept to how some folks make blanks to become floor lamps. The threaded rods would be long, and probably a little pricey, but the advantage is they'd apply squeezing pressure to the whole assembly so even if the planks crack or otherwise get damaged over time it would not be a problem as they aren't the main structural pieces. Use a router cove bit, instead of a dado stack, and you'll have circular cross section channels that you could epoxy the threaded rod into for a really beefy structure.

        A variation is to use hanger bolts - those that are wood threads on one end and machine screw threads on the other end. Again, you'd have to bore through the posts for washers and nuts if you put the machine screw end into the posts. You could put the wood threaded end into the post, then drill a channel into the end of the plank for the machine screw end; use a Forstner bit to drill from the inside face of the plank to the end of that channel for a washer+nut similar to some counter top or bed frame attachment methods. This would allow future disassembly of the project to repair/replace pieces.

        Big dowels or Dominos/floating tenons possibly?

        mpc

        Comment

        • LCHIEN
          Internet Fact Checker
          • Dec 2002
          • 20920
          • Katy, TX, USA.
          • BT3000 vintage 1999

          #5
          Originally posted by radhak
          I want to attach two 6" wide boards to a 2" square post, essentially butt-joints for the 'aprons'. (see pic below)

          This will be for an elevated garden bed in the yard, so nothing fancy, but I can't have it fall apart too soon. I don't want to go cutting dadoes for this.
          I thought pocket screws, but will they stand the weight of 12 cu.ft of soil?

          Maybe I could add a tiny supporting bracket below each apron end, and that should be enough reinforcement? Or should I add a crossbar on the inside that I can attach to the post with screws?

          first concern:
          A cubic foot of soil weighs between 74 and 110 pounds, depending on the type of soil and how moist it is. Dry, loose dirt weighs about 76 pounds per cubic foot, while moist, loose dirt weighs 78 pounds per cubic foot. How Much Does a Cubic Foot of Soil Weigh? | Reference.com

          www.reference.com › Science

          Yeah, you are looking at possibly more than 1200 pounds, more than 300 pounds on each corner joint for water saturated dirt.

          You can't cut corners on this one.
          Mortise and tenon. Or some beefy, multiple dowels.
          Your best bet is to add a 45° crossbrace that is securely fastened into each side apron and then a couple of big lag screws (or hangar bolts) into the leg. Or they offer some steel brackets for this.
          Remember this is NOT a table where the weight of the table top as well as the load on the table top will be resting on the legs.
          If you hang some stuff and the weight is hung from the aprons the joint will be carrying a LOT of weight and the 3/4" boards will be carrying several hundred pounds.

          Some serious beefy legs like a 4x4 might be better with 2x6 aprons so you can get some serious fasteners into it.
          If looks and craftsman ship are not primary but quick is, 4x4 legs and 2x6 aprons lag screwed two in each end to the side of the leg might be stronger ultimately and give you the simplicity of a butt joint.

          I'm really serious about the weights!
          Tiny brackets will not serve you well..

          Last edited by LCHIEN; 04-23-2020, 02:10 AM.
          Loring in Katy, TX USA
          If your only tool is a hammer, you tend to treat all problems as if they were nails.
          BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

          Comment

          • radhak
            Veteran Member
            • Apr 2006
            • 3058
            • Miramar, FL
            • Right Tilt 3HP Unisaw

            #6
            Very good points, everybody! Loring, that weight aspect is spot-on!

            I have the Dowelmax, so I will use dowels for the joints, and then add cross braces at all four corners.
            Since this will be a 6' long bed, I will also add small posts/legs in the middle at the 3' point.

            Probably a wee bit more time and effort needed than planned, but best for peace of mind, and where else am I going, these days?!
            It is the mark of an educated mind to be able to entertain a thought without accepting it.
            - Aristotle

            Comment

            • capncarl
              Veteran Member
              • Jan 2007
              • 3564
              • Leesburg Georgia USA
              • SawStop CTS

              #7



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              I like this construction for table/ apron connections over mortise an tendons. My sawmil owner had this table leg and apron demonstration piece showing how he constructed tables. I like it for a sturdy table. I would probably finalize it by putting in a couple of pocket hole screws to tighten it up.

              like Lchien said, it’s a lot of weight. Considering this fact you might consider making a sturdy bench and set the planter box on top of it. 4x4 legs might be in order to keep it sturdy and reduce the chance it might tip over.

              Im not sure I wouldn’t just screw the aprons to the side of the legs rather than trying to make it like a table. Either way you have to deal with how to cut in the box bottom to prevent leakage.
              capncarl

              Comment

              • radhak
                Veteran Member
                • Apr 2006
                • 3058
                • Miramar, FL
                • Right Tilt 3HP Unisaw

                #8
                That's a very interesting contruction, Cap! And I don't think it should be very difficult to cut either.
                I'll try and incorporate that in my next project, thanks.

                My backyard is full of shale and limestone, so I'll need a number of raised/elevated beds to make for good planting. Let's see if I can make a quick but job of all of that!
                It is the mark of an educated mind to be able to entertain a thought without accepting it.
                - Aristotle

                Comment

                • capncarl
                  Veteran Member
                  • Jan 2007
                  • 3564
                  • Leesburg Georgia USA
                  • SawStop CTS

                  #9
                  I really like the raised bed concept using a really raised bed......I wish it would work for me. If I built a raised box I would be hesitant to visit the garden without my hand cannon for fear of meeting up with one of our crawling critters. I’m cautious anyway with the short boxes full of plants but have never found a snake in any of the garden, but under something in the cool damp shade is asking for trouble here. My garden boxes don’t last but 3-4 years before they rot out. The boxes in the photo are about 2 ft deep, with about 16” of the hard red clay being dug out and the boxes filled with mushroom compost. Photo taken late Feb before planting the summer garden.Click image for larger version

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                  Comment

                  • Carlos
                    Veteran Member
                    • Jan 2004
                    • 1893
                    • Phoenix, AZ, USA.

                    #10
                    We have a raised garden made from block for our main veggies, and three wood raised beds for herbs. I used Ipe wood, and it's showing no signs of giving up life. I think that will outlive me. I know Ipe isn't common, but the marina where we kept our boat would let me take all their scraps. I store it outdoors, and it was already outdoors. So the stuff has been in the AZ sun for at least a decade already. You can't kill it. It's hard as heck so a pair of screws holds it tight.

                    Comment

                    • radhak
                      Veteran Member
                      • Apr 2006
                      • 3058
                      • Miramar, FL
                      • Right Tilt 3HP Unisaw

                      #11
                      That's a good point about snakes - I have not seen any around, but this is South Florida, so they're bound to be there. I should see what I can do about that.

                      I have always thought of Ipe as a good choice (by reports) but have found it expensive; but we too have marinas here, so I should start asking around if anybody has scrap for sale. Thanks!
                      It is the mark of an educated mind to be able to entertain a thought without accepting it.
                      - Aristotle

                      Comment

                      • durango dude
                        Senior Member
                        • Mar 2011
                        • 934
                        • a thousand or so feet above insanity
                        • 50s vintage Craftsman Contractor Saw

                        #12
                        Dowels

                        Comment

                        • capncarl
                          Veteran Member
                          • Jan 2007
                          • 3564
                          • Leesburg Georgia USA
                          • SawStop CTS

                          #13
                          The SE has a lot of large reservoirs with illions of boat docks. Being US Corps of Engineers, TVA of other management the building of the docks are pretty much regulated and most of the high end docks are IPE or another wood exoctic wood that slips my memory. I’ve talked with a few of the dock builders in SC about their leftover wood. It’s not called scrap! They plan their waste cuts. If there is going to be a 12” cut off they know that is useless with no value to anyone, so they might use longer to get a useful piece for themselves or the people that buy their leftovers to make dock chairs and tables. These adarondack chairs bring a premium price.

                          Comment

                          • jon_ramp
                            Established Member
                            • Feb 2007
                            • 120
                            • western Chicago burb
                            • Craftsman 21829

                            #14
                            4x4 posts and 2x aprons joined with joist hangers might be an option. I once used 'water proof' glue and dowels to create a frame to hang an archery target. It lasted only about 2 years in the weather before falling apart.

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