Corner Unit Joinery - ideas?

[Cam.H]

Hi Guys,

I have a corner unit to make. To date I have never made one.

My question is on the joinery method to use when affixing the shelves to account for seasonal movement.
It seems as the though the boards would be moving in different directions.

Attached is a drawing to clarify the design. Shelves would be fixed opposed to floating.

I thought the middle shelf could be attached with a loose tenon glued into the sides of the unit and pinned in the shelf (loose and dry). I'm still not sure this would work, and doesn't resolve the top etc.

Any ideas?

Cheers,

Cam.

365615

[Arron]

I think they should all be moving in the same direction and at the same rate.
Direction of movement is is away from the corner.

if there is any difference in movement then it will be tiny so pva should have enough creep to handle it.

Also, why wouldn't you just screw bottom two shelves in as heads can't be seen. fix the top shelf with glue and dowels.

[Cam.H]

Thanks!

I think they will be moving in a similar directions, and hopefully you're right in that it will be minimal enough not to matter.

If in fact that's the case, then affixing all shelves will be straight forward enough with dowels/dominos etc.

Thanks for your help.

[rrich]

I apologize for the Imperial measurements as I never have and never will be one with metric.

I would put the top, bottom and shelf into 1/4 inch stopped dadoes. Stop the dadoes about a half inch from the edge and back of the sides. You'll have to trim about an inch off the front corner of the shelves and about 1/4+ deep.

I'm assuming that the sides are two feet front to back. Trim about 3/8 inch off of the back corner. This should allow for wood movement from costal humidity to desert.

The tricks for assembly are to use screws with elongated holes and sink the screw heads. Cover the screw heads with a contrasting plug, like ebony. Finally glue the front 3 or 4 inches of each shelf.

All the movement will be toward the back where you have trimmed the corner.

With all of that said. . . .

If the client will allow, use a good veneered plywood (19 MM) and edge glue a matching piece of timber to the edges of the shelf. With the plywood, the top shelf could be made with a small overhang and edging.