Wish to maximize sliding dovetail joint

[David Utterback]

I have read several threads on SMC about sliding dovetails and have also used them a few times. My current project is a cherry book shelf that will also serve as an end table for our couch. I am planning to use a single upright to join the top and bottom shelves and offset the upright from center. The shelves are 9 1/8" wide and the shelf stock is 1" and the upright is 1 1/4" thick. The sliding dove tail would only reach about half the width of the pieces with a butt mount appearance on the front.

Would the strength of the sliding dove tail be maximized through some combination of width of shoulders and the male dovetail? I was imagining the shoulders might be strongest if they were about 1/3 the thickness of the upright on each side of the dovetail. I also would guess that a greater dovetail angle would increase strength - say around 14 degrees with a depth of around 1/2". I could even try to haunch the joint but would that have any real impact on joint strength?

Please let me know what you believe to be a good solution. I have read the thoughts on dovetails vs. m&t joints in these earlier posts. https://sawmillcreek.org/showthread....ail-vs-M-amp-T

Thanks

[William Fretwell]

Interesting design idea. Is the upright attached to the base with mortice and tenons or another sliding dovetail? The 1/3 ratio seems about right but the thickness of the upright a little meagre. Depending on the length of the upright the bottom joint may take considerable force.
Why not make the sliding dovetail full width, maximize the strength for the same appearance? I doubt the dovetail angle will be much of a factor given the length.

[David Utterback]

Thanks, William. With no other response for a couple of days, I believe the forum silence reflected it's wisdom.

Yesterday, I pretty much abandoned the idea and thought using a more traditional approach would be better. I had considered reinforcements of the joints with a short brace glued to the surface of the shelves in notches at the back of of the upright. That joint would be cross grain in the upright which made me think it would may not improve racking resistance that many had stated was the main problem with the sliding dovetail. The project may be abandoned for a while because I am scheduled for a knee replacement next week at this time. Plenty of idle time to consider other approaches during my initial recovery. Thanks again.

[Weogo Reed]

Hi David,

Sliding dovetails fascinate me, particularly tapered sliding dovetails, for
the possible 'knock-down' aspect, and that they can be maintained over time,
with the addition of shim material on the sides of the dovetail.

I'm working on the design of a low meditation bench, somewhat like a Japanese Seiza bench, sort of like this:
https://i.pinimg.com/236x/6c/42/aa/6...93b1.jpg?nii=t
To use, one sorta sits on their legs, with backside on the bench, which can pivot for optimal posture.
Am thinking of using a tapered sliding dovetail to attach the leg to the seat.

It would be great to know if there is some solid research on dovetail widths, depths and angles.
Does anybody know of anything published?

If I'm imagining your dovetail use in your bookcase correctly, I think it's has merit, and
it would be great to see the finished product if you go this route.
If I correctly understand what you are doing, I think a haunch would likely reduce the joint strength.

Thanks and good health, Weogo

[David Utterback]

Thanks, Weogo. I think I could hurt myself on that bench.