I snagged the image below while looking online for dovetail examples.

enter image description here

Instead of two boards coming together, it appears that the joint, what I called the spine in the title, is a third piece to which both boards connect. (Example 1, 2, 4, and 6 reading left to right)

  • Is there a particular name for this type of join that differentiates it among other dovetails?
  • Would this have any effect on the strength of the joint?
  • 1
    I can't quite tell what the structure of the third joint is. The photo is a bit too small for my poor eyes to read the grain direction, but it looks like a variant of a keyed miter joint. Am I seeing that right? Feb 22, 2019 at 20:15
  • 1
    @GernBlanston counting from the left, examples 3 and 5 appear to be keyed miter joints. But, I'm looking at examples 1, 2, 4, and 6. I suppose they could be keyed miter's as well, but the key is running the full height of the joint?
    – Hueco
    Feb 22, 2019 at 20:36
  • 1
    Yep, I think we're on the same page. My answer is based more on examples 1, 2, and 6. I'd call number 4 a box joint instead of a dovetail. Feb 22, 2019 at 20:40
  • I've seen other variants of this called "double dovetail" joints. I would think these would qualify, but I'm not 100% sure about that. Feb 22, 2019 at 22:34
  • I think 3 is the same as 1, except that the tails in the light wood have been extended and mitred. I would expect there to be a solid spine of the dark wood at the inside corner. Similarly 4 is a reworking of 2. Feb 25, 2019 at 17:32

1 Answer 1


Yes, this will have an effect on the strength of the joint. Since the "spine" (I like your name for it) is one piece of wood, with all of the grain running in the same direction, one of the sets of pins will be cut across the grain, instead of along the grain, making it pretty weak in that dimension. Also, if there's any looseness in the fit of the joints, that will be compounded by the fact that you have twice as many joints now.

How much that actually matters depends on the application. If it's a decorative piece that won't be handled much, the unique look could be worth the tradeoff.

(I don't know if there's a name for this.)

  • 1
    unless you go with the grain diagonally instead of parallel to one of the sides being connected. but that just moves where the weakspot is. Feb 26, 2019 at 12:26

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