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Thread: C-Table Miter Joint Reinforcement - necessary? Suggestions?

  1. #1

    C-Table Miter Joint Reinforcement - necessary? Suggestions?

    The boss has handed down a request for a C-Table like the one pictured. My main concern is the strength of the joint where the top meets the vertical back (obviously).

    Does anyone have an appreciation on how strong a joint would be under these circumstances? In this case the joint is just a 45 miter joining 2.5" thick boards. I can do it the same way, or not.

    What would be alternatives to a simple miter for a stronger joint? Would splines add much to the strength of the joint?

    Thanks!

    Eustorgios+End+Table+with+Storage.jpg

  2. #2
    Glue surface is the key to strength. The more glue surface the stronger the joint. Splines would certainly add strength. One key thing to remember when gluing up miter joints in solid wood. You are essentially gluing end grain and end grain will suck the glue right out of the joint. You should always apply glue to both sides of the joint before assembly and insure you get some gle squeeze out for optimum joint strength.

    I would make my splines for these joints with the grain 90 degrees to the length of the spline so it aligns closer to the grain direction in the pieces you are assembling. Making splines in this manner will be harder, but in the end they will make a stronger joint. This is where loose tenons would excel.
    Lee Schierer
    USNA- '71
    Captain USN(Ret)

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  3. #3
    Agree with everything Lee said, an additional consideration is whether you want the joint reinforcement to be just that or if you want it to be a feature also. Rather than the spline that Lee describes running along the joint you could also use cross splines in a contrasting wood or dowells also in contrasting wood drilled and installed top and or side after the joint is assembled.

  4. #4
    If it's going into a public or commercial area (as opposed to someone's home), I'd bury some steel in it because someone will sit or climb on it. The L brackets made for mounting unsupported countertops to wall would work.

  5. #5
    Quote Originally Posted by Lee Schierer View Post
    Glue surface is the key to strength. The more glue surface the stronger the joint. Splines would certainly add strength. One key thing to remember when gluing up miter joints in solid wood. You are essentially gluing end grain and end grain will suck the glue right out of the joint. You should always apply glue to both sides of the joint before assembly and insure you get some gle squeeze out for optimum joint strength.

    I would make my splines for these joints with the grain 90 degrees to the length of the spline so it aligns closer to the grain direction in the pieces you are assembling. Making splines in this manner will be harder, but in the end they will make a stronger joint. This is where loose tenons would excel.
    Thanks Lee. Can you elaborate on the spline grain orientation? Im having a hard time visualizing. Are you saying the grain should be running the width of the spline (opposed to the length)?

  6. #6
    Quote Originally Posted by Paul F Franklin View Post
    If it's going into a public or commercial area (as opposed to someone's home), I'd bury some steel in it because someone will sit or climb on it. The L brackets made for mounting unsupported countertops to wall would work.
    I wish I could bury some steel in there. It'll be in my own home so it should be pretty manageable, but Im envisioning someone sitting at a couch and putting their weight on the front edge to help push themselves up off the couch (or something) and it just snapping. I can manage splines pretty easily. I don't have a convenient way to implement floating tenons in a 45 miter.

  7. #7
    On the base, you can drill up into the vertical leg and use either steel rods or timberlok screws up into the vertical piece to add strength.
    608309410591lg.jpg
    Lee Schierer
    USNA- '71
    Captain USN(Ret)

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  8. #8
    Quote Originally Posted by Lee Schierer View Post
    On the base, you can drill up into the vertical leg and use either steel rods or timberlok screws up into the vertical piece to add strength.
    608309410591lg.jpg
    You could also use this to reinforce the top joint by drilling thru the vertical leg into the top, countersinking the screw and plugging the hole.

  9. #9
    Join Date
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    Quote Originally Posted by Lee Schierer View Post
    On the base, you can drill up into the vertical leg and use either steel rods or timberlok screws up into the vertical piece to add strength.
    608309410591lg.jpg
    A friend has used these extensively during the construction of his timber frame cabin. These screws are incredible. I have not seen a single one that broke or bent even when driven into white oak timbers.
    Rustic? Well, no. That was not my intention!

  10. #10
    I would do a row of 3/8" or even 1"2" dowels. I don't know the width of the board, but I think if it's an end table, a row of 8 or 10 would make the joint unbreakable. I see you're talking about 2.5" thick boards.

    The suggestions to glue the end grain surface with a glue size first is a good one.

    If you own a dowel jig like the Jessem it would be perfect. The Jessem would allow you to stagger the dowels and install more in the process. If no Jessem, a shop made jig specific for this project would take no more than 15 minutes to make.

    If you own or have access to a Domino machine, a row of tenons like that would be an excellent method of joinery for this application. Or if you have another method of mortising, like a jig/router.

    If you have a biscuit joiner, two rows of biscuits might be a way to go. I would use the largest biscuits you can, probably #20, and glue them very carefully and liberally. This would not be my favorite choice but I think it would work and be expedient to do.

    How do you plan to clamp the 90 degree joint?

    Edwin

  11. #11
    That table looks like it's veneered. Look at the way the grain is running in the top and bottom pieces. That may hide more robust joinery.

  12. #12
    I found your table kind of interesting, so I did a quick google search and came up with one from Hayneedle that is not identical but very very similar. The differences are that the corners don't appear mitered, and the drawer in the Hayneedle one is almost imperceptible, basically hidden unless you knew it was there or discovered it. You can see it here and below: https://www.hayneedle.com/product/su...tray-table.cfm. The dimensions of this table are 16x16x23h. If someone sat on the end of the table, no doubt it would exert a lot of leverage on the corner joint. But at 16" I think the joinery methods mentioned above would hold up to it. A person using it to assist themselves getting up from a sofa should be no problem.

    The bane of the woodworker is seeing something like this on a website for $264 shipping included and then determining whether it would be worth the time and materials cost to make it yourself. I suppose it depends on how much time you have and whether you enjoy woodworking enough to possibly pay a premium to do it. Especially if the project requires buying more tools to complete it (like gulp, a Domino machine, well over $1000).

    As someone else pointed out, the original image looks veneered. It might not even be veneered with wood, it might be a faux product of some kind. The veneering could basically create a mock miter at the waterfall where a structural one does not even exist.

    I think the design looks better to my eye with the miter, and could look very interesting if the edges were shaped or beveled in some way, maybe at 30 degrees though that look would take it even more in the modern direction. If it were me, I wouldn't want to see end grain at the edges, so I might make this out of laminated cabinet grade plywood and veneer all the edges (which is where you could "create" the miter). Hope this helps


    options_SUNP528_15_Espresso.jpg
    Last edited by Edwin Santos; 11-22-2019 at 12:38 PM.

  13. #13
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    Eventually someone will stand on this to install a light bulb.

    Splines will provide a lot of strength, probably plenty if you use a lot of them. You could add a triangular glue block in the inside of the corners. If it is a little short of the ends it will not be noticeable.

  14. #14
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    Quote Originally Posted by Christopher Juncosa View Post
    ... In this case the joint is just a 45 miter joining 2.5" thick boards....
    How would you cut a 2.5"-thick board at 45 degrees? My 10" Unisaw cannot do that. At 45 degree bevel, it can barely cut 2", and I'd have to find a true 10" blade to do that. All my supposed 10" blades are actually 9 3/4" or so.

  15. #15
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    I'd redesign the table to not have a bevel joint. I'd use a simple 90 degree joint. It is easier to cut, and it is much easier to make the joint. I'd use a row of dowels, or dominos. Or if you want to exercise your woodworking chops, use big dovetails or a big box joint. As woodworkers, we all immediately see the bevel joint. Most people don't see that detail, and would be just as happy with a simple 90 degree joint.

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