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Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

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  • Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

    Hi all,

    In the process of cutting a haunched mortise/tenon for a table leg, I accidentally took too much off for the haunch. The mortise is 1" deep. It was supposed to have room for a 1/4" haunch, but I somehow managed to make it 5/8" deep. That leaves me with only 3/8".

    ​​​​​​Although the joint ended up being pretty tight, having only 3/8" worries me because I feel like there is way too much wiggle room.

    Can I reinforce this joint with a pin? Say a piece of a dowel (1/4" or 3/8" in diameter) going through the center of the tenon?
    Egon likes this.
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  • #2

    Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

    End grain on glue ups have next to zero strength so having a tenon going all the way down to the bottom of the Mortise other than having more gluing surface.

    How loose are we talking about here. Is it grabbing a little on the sides of the mortise or is it completely loose. Having a tenon that is way too tight will starve the joint of glue so if you you can feel it have a little surface tension you should be good to go.

    Putting a pin in is always a good idea. Even if it's only a toothpick. They have been pinning joints together for millennia and some furniture survives to this day. With today's glue It should be fine.
    paulsz likes this.

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    • #3

      Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

      Yeah, I agree with bogmer regarding the strength of end grain glue-ups.

      Your dowel idea should work out.
      paulsz likes this.
      All the best,

      Marty

      Secretary of Kingston Wood Artisans Inc. https://kwoodartca.wordpress.com/

      Master Mistake Fixer (because I've made them all... at least once)

      Comment


      • #4

        Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

        Originally posted by bogmer View Post
        End grain on glue ups have next to zero strength so having a tenon going all the way down to the bottom of the Mortise other than having more gluing surface.

        How loose are we talking about here. Is it grabbing a little on the sides of the mortise or is it completely loose. Having a tenon that is way too tight will starve the joint of glue so if you you can feel it have a little surface tension you should be good to go.

        Putting a pin in is always a good idea. Even if it's only a toothpick. They have been pinning joints together for millennia and some furniture survives to this day. With today's glue It should be fine.
        The joint is pretty tight as is. Loose enough that i can fit the tenon in with arm strength, but tight enough that it supports itself.

        I was mostly wondering about the future risk of twisting. The glue would hold the joint in place well. But if it were to be subjected to a decent amount of weight over the next couple of years, would it be a risk of twisting? Would a pin help prevent that?

        Comment


        • #5

          Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

          This is a visual of what my concern is (note: I drew a cross section of the joint). The drawing is exaggerated, but you get the point. Would the joint be a risk of this over time?
          Attached Files
          Last edited by paulsz; 11-28-2019, 09:40 AM.

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          • #6

            Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

            The mortise length doesn't matter in my opinion. If the joint is tight then for it to wiggle out then the glue will need to fail and today's glue is stronger than the wood.

            Like I said before. Using a pin have held furniture together for thousands of years... So I will never say don't pin furniture. Plus it ads a decorative feature.

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            • #7

              Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

              I’m inclined to think that as long as the joint isn’t starved for glue, it’ll be fine as is. The pin certainly wouldn’t be a bad idea would it. I agree with bogmer on the strength of a quality wood glue, like titebond 2.
              VIDEOS: www.youtube.com/AWoodworkersLife

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              • #8

                Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                Use lots of glue mixed wit sawdust in the mortice. Put in two pins, either from the side or the end. If from the end ensure they are longer than the tenon. Screws would also work from the end and put plugs in the holes.
                Egon
                from
                The South Shore, Nova Scotia

                Comment


                • #9

                  Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                  Originally posted by Egon View Post
                  Use lots of glue mixed wit sawdust in the mortice. Put in two pins, either from the side or the end. If from the end ensure they are longer than the tenon. Screws would also work from the end and put plugs in the holes.
                  Egon, what’s the purpose of diluting the glue with sawdust in this application?
                  VIDEOS: www.youtube.com/AWoodworkersLife

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                  • #10

                    Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                    Make volume.
                    Egon
                    from
                    The South Shore, Nova Scotia

                    Comment


                    • #11

                      Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                      Originally posted by Egon View Post
                      Make volume.
                      But it was already stated that the joint is tight, no? Is this something you’ve tried before?
                      VIDEOS: www.youtube.com/AWoodworkersLife

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                      • #12

                        Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                        There may be a void at the end of the tenon.

                        Yes, I have glued up one or two joints. The mortices were made just using a chisel.


                        Click image for larger version  Name:	image_128158.jpg Views:	3 Size:	745.8 KB ID:	1260726Click image for larger version  Name:	image_135067.jpg Views:	3 Size:	1.82 MB ID:	1260727
                        Attached Files
                        Last edited by Egon; 12-03-2019, 04:27 PM.
                        Egon
                        from
                        The South Shore, Nova Scotia

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                        • #13

                          Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                          Sorry, may have been some miscommunication. I didn’t mean to ask have you made mortises, I was wondering if you’ve used a mixture of sawdust and glue in a tight M&T application like Paul was referring to? If the PVA has a higher tensile strength than most woods, what’s the advantage to mixing a bunch of sawdust in it.
                          VIDEOS: www.youtube.com/AWoodworkersLife

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                          • #14

                            Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                            Most woodworking glues are water-based. For argument sake, let’s just say 20-30% water. When you have a good fit, the glue is actually stronger than the Wood. When you have a loose fit, sometimes it is best to fill the void with solid wood. If you have just a slightly loose fit. Yes, a mixture of sawdust with wood glue gives a better loss in shrink of the word glue, helping filling the void.

                            Now, if the mortice is too deep, you can fill the bottom with a good fit plug glued. Or,... You can fill it with a sawdust glue mixture. But… I prefer to fill it with something solid if it exceeds 3/16” all glued up. I personally do not like to use glue and sawdust trick or anything more than 1/16 of an inch.
                            For every action there is an equal and opposite reaction.
                            Sir Isaac Newton.

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                            • #15

                              Re: Haunch in my mortise was cut too deep - can I reinforce tenon with a pin?

                              Originally posted by Matt Matt View Post
                              Most woodworking glues are water-based. For argument sake, let’s just say 20-30% water. When you have a good fit, the glue is actually stronger than the Wood. When you have a loose fit, sometimes it is best to fill the void with solid wood. If you have just a slightly loose fit. Yes, a mixture of sawdust with wood glue gives a better loss in shrink of the word glue, helping filling the void.

                              Now, if the mortice is too deep, you can fill the bottom with a good fit plug glued. Or,... You can fill it with a sawdust glue mixture. But… I prefer to fill it with something solid if it exceeds 3/16” all glued up. I personally do not like to use glue and sawdust trick or anything more than 1/16 of an inch.
                              Ahhh. I see what Egon is saying now. That makes sense with regards to shrinkage. Thanks for taking the time to clear that up.
                              VIDEOS: www.youtube.com/AWoodworkersLife

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