Another Design (Construction) Question

[Admiral]

I'm building my bride a base cabinet with doors (36" wide x 19" deep x 28" high) and on top of it will be a 40 inch high bookcase, 12" deep.  I'm putting a top on the bookcase portion of 7/8" thick cherry.  Question is how to attach the top; my current thinking is either (i) just to nail it off with perhaps 3 or 4 nails, or (ii) use a center loose tenon, glued, with two nails on either side, or (iii) use a figure 8 tab, like a table top.  My concern is to address wood movement.  I will not pocket screw.

What sayeth the brain trust?

[Willyou]

A picture or sketch would help. Without knowing more about how the top will be made and how the grain direction relates to the bookcase, I vote for the figure 8s. Simple, secure, and addresses wood movement if the centerline of the 8s are parallel with the grain (perpendicular to movement).

[iclark]

+1 on the figure-8's or the functionally similar little Z-clips used to attach table tops to legs or aprons.

Assuming you are using plywood for the back, you might need to allow for differential length change between the top and the back. That would seem to be the biggest problem with just doing one dowel at the center (depth-wise) of each side.

If you are worried about the clips showing, I wonder what would happen if you just cut a shallow rabbet/dado in the underside of the top (to match the top of the 2 sides, back, and front frame(if there is one)) and just let the top sit on top of the bookcase (with those grooves to hold it in place laterally). Unless someone goes out of their way to light the underside of the top, the slop in those grooves to allow for seasonal expansion/contraction will never be seen.

[Philip1231]

I guess I am not understanding why there is a grain direction issue? Wouldn't the grain direction of the sides of the bookcase be the same as the top?

[Admiral]

I guess I am not understanding why there is a grain direction issue? Wouldn't the grain direction of the sides of the bookcase be the same as the top?

Thanks to all for their input.

Philip:  right, yes they would.  I'm overthinking this and confusing myself; I'm in the stage of drafting plans to scale and making construction notes about everything that could possibly come up . . .

"Plan for what is difficult when it is easy."  Sun Tzu

[Willyou]

Thanks to all for their input.

Philip:  right, yes they would.  I'm overthinking this and confusing myself; I'm in the stage of drafting plans to scale and making construction notes about everything that could possibly come up . . .

"Plan for what is difficult when it is easy."  Sun Tzu

Even if there is no cross grain issues, the figure 8s are a good secure easy way to fasten the top down.

[Philip1231]

OK, since there is no grain direction issue, I vote for some fancy dovetails!

Thanks to all for their input.

Philip:  right, yes they would.  I'm overthinking this and confusing myself; I'm in the stage of drafting plans to scale and making construction notes about everything that could possibly come up . . .

"Plan for what is difficult when it is easy."  Sun Tzu

[MstrCarpenter]

The Freshman project at that vocational school in my signature line was a mahogany bookcase. The top is attached with three dowels into the endgrain of each side. I can lift that bookcase by the top even when it's full of books. The next project was a two drawer night stand; the top was installed the same way. The chest of drawers used dust panels with an open frame at the top; that top was held to it with pan head screws in short slots.