Wood movement for solid board shelving

[Dave Rosner]

Hi All - I'm making a small shelving unit and i prefer to use 4/4 boards instead of plywood. The shelves will be 16" wide walnut which according to my research could mean 1/8-1/4" of movement in my area. My design is similar to the picture below where i'll use 4/4 boards with a front and side face frame if you will to give it some more heft of a look. If i only had the front runners (frame?) then i think i'd be ok with expansion since all 4 of the shelves would move together with the seasons.

I'm just not sure what to do with the side runners - do i have to do some sort of breadboard approach here for the side? Thoughts from others who have done this before?


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[Lee Schierer]

I can't tell from the photo if the cross pieces in the frame sides are end grain of the shelves or long grin pieces making up the frame. If they are the ends of the shelves you should have no issues with seasonal dimension changes. If they are long drain pieces then I would make the shelves so they are attached at the front and allowed to move along the ends and back.

If those electron tubes are going to be energized for any length of time the heat will tend to dry out the shelf above more than the others.

[Jim Becker]

Assuming the runners are attaching to the side of the cabinet to support the shelves, fixed screw in the front and a floating screw in the back...or a sliding dovetail only glued at the back. The runners will be hidden by the face frame drop in the front for the most part, and any fasteners can be either colored to hide or plugged to hide.

[Dave Rosner]

So was thinking I’d glue the front frame to the shelf and then Glue the shelf in the front AND the back. I’m assuming all shelves move about the same so if the bottom expands then th above shelves expand equally and I’m ok - nothing splits.

If I’m good there then I just need to allow the side runners/frame to allow the shelf to move while the runners are fixed. That’s an end grain to long grain connection. That’s the part I’m stuck on. If this was a big table I’d do a traditional breadboard. But this is different and not sure that approach will work.

[Jim Becker]

So was thinking I’d glue the front frame to the shelf and then Glue the shelf in the front AND the back. I’m assuming all shelves move about the same so if the bottom expands then th above shelves expand equally and I’m ok - nothing splits.

I'm a little confused because you say "...I’d glue the front frame to the shelf and then Glue the shelf in the front AND the back..." What are you gluing here besides the front frame? The reference to the back isn't making sense. The runners that the shelves sit on are the cross-grain issue. (this assuming everything is solid stock with grain oriented the same, presumably parallel to the front/back of the case)

[John TenEyck]

I would glue the shelves to the faceframe, only. If you cut dados in the side runners and back cross pieces then the shelves will expand/contract as they want while still being supported.

John

[Dave Rosner]

Appreciate the suggestions from this group and I realized I’m overthinking this. But allowing me to post and your responses helped me get to the answer.

I’ll build the structure with legs and the frame/rails on front and side all glued up. That will be the supporting structure and will be plenty strong without the shelves.

Then I simply put the shelves sitting on rabbets on those pieces. I can leave them entirely floating or secure the fronts to stop shifting of the shelves. There is no reason to join them to the sides or the back as long as they have support from underneath. If I fit it tightly I can minimize the visible gap.

it’s kinda like a drawer bottom upside down but instead of slots I use rabbets on side and back…

[Tom Bender]

How about making the ends in solid wood with the grain vertical. You can dovetail the joints for a nice look. If you want to open up the ends you can cut some windows, even add glass, maybe colored glass.

[Thomas McCurnin]

Plywood is made for this application and would be best. Second prize would be MDF with a nice veneer.

If I had to make the shelves out of solid wood ... consider quarter sawn wood .... consider quarter inch back and fasten shelves to back with screws and to face frame with dowels or biscuits ... use dado on sides to capture shelves