Help assembling sofa table
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I just finished the mortise and tenon joints of my sofa table. I thought I would assemble all the joints to see how they looked, but I’m having trouble getting the joints completely seated. I’m sure none of the joints are too tight, and each joint seats easily by hand pressure by itself. Each pair of joints seats fine, but when I try to do them all at once, one or two won’t seat. I’m using two clamps, one at the top and one at the bottom of the joint, making sure the clamps are parallel. At the same time I’m using a mallet to help the clamps. But I reach a point where I can’t turn the clamps any tighter by hand and some of the joints ( not always the same ones) still have 1/2 inch or so to go. Is there a secret to doing this?
11 July 2017 at 12:24 pm #313648Perhaps your mortises aren’t deep enough. You can gauge the depth with your chisel and compare to the lengths of your tenons. That’s what it sounds like to me.
12 July 2017 at 3:08 pm #313670you check by seating each one separately and checking for square on all planes, like Ed said , something isn’t in the right spot.
If you find that a mortise is out of angle, there’s a good chance that only a small adjustment is needed to achieve assembly of the table. That adjustment might make a joint (or joints) too loose. If so, you can saw a thin bit of material from some scrap and glue it to the face of the tenon. So, this piece would be the size of the full tenon cheek and 1/16″ (or whatever) thick. Now, the tenon is too thick, so trim to fit the enlarged mortise. Voila, a good fit in the modified mortise.
The gotcha here is that if you need to make a slight angle, you may open a gap at the shoulder line of the tenon. If you can arrange things so that the gap is opened on the inside of the table apron where it won’t be seen, you can just let it be. Only you will know. The other option is to pare the shoulder to the slight angle adjustment you made to the mortise. This *may* mean that you will need to adjust the length of the other apron. So, if you adjust, say, the a shoulder on the long front of the table, you may need to do the same on the back apron. Or, you may not…the structure may absorb it. But keep it in mind.
This reminds me that the other reason you may have trouble is if your apron members are not equal lengths, but since you say you can’t sink the last half inch, I don’t think that is what is going on. However, if you are pulling your joints all the way home one by one, this *could* be a problem. Instead, start all the joints and then progressively seat each one a little bit and make many trips around the structure so that it all comes home at once. So, put on all four clamps (8 clamps?), and just do a turn at a time on each clamp and work around and around the table.
Finally, if you can identify an out of whack tenon (angle), you may discover that only the deep part of the tenon is causing trouble. You might see that the deepest 1/4 or 3/8″ of the tenon is bruised or shiny while the shoulder area is fine. If so, you could take a shaving off of *just the end* in the bruised area. You end up with a somewhat out of whack tenon that fits well up at the shoulder area, fits well on one face, but has a hidden gap on the other face for the last 1/4 or 3/8″ buried deep in the mortise. This isn’t ideal, but it could let the structure come together and probably is strong enough to never give a problem for a sofa table. (You might feel differently if this were a chair).
Hope this helps. Let us know how it turns out!
I hate to admit what was causing my problem. You know how you are supposed to cut the ends of the tenons at 45 degrees? Well, it appears I missed a couple of them. So entitydigital’s guess was the closest. Those two mortises were 3/8″ too shallow because the adjacent tenon was in the way. I’d like to think I’m not the first person to do this, but it’s still pretty embarrassing.
Thanks to all who took the time to try to help me out. My table joints fit great now.Don
14 July 2017 at 9:56 am #313725Well normally I’m wrong, so I’m chalking this up as a win even if I wasn’t right on the money! 🙂
Rob.
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