Shelf Length / structure

[Ray Schafer]

I am building cabinets for my garage and workshop. Y'all helped me with the finish issues. Now I have a question about the shelves.

I am going to build cabinets of varying widths and depths. Some will need to be 36 or 48 inches wide. I know that if I go more than about 24", the birch plywood adjustable shelving will no long be sufficient as is. I was thinking about using pine boards as the shelves for the longer ones. Since this is my garage, I am not too concerned about the look of the shelves (which will be inside closed cabinets). I am just concerned about the wieght that they will hold and deflection.

Can you please share your ideas on how I should construct the shelves to be quite wide and sturdy? Ideas on the how to hold them in place (and maybe keep them adjustable) would help, too. My first prototype was made with pin holes for adjustment.

Thanks.
Ray

Thanks.
Ray

[Jamie Buxton]

Shelf stiffness goes up as the cube of thickness, so the best way to make them stronger is to make them thicker. If shelf weight or materical costs makes the thickness too much for you, make them as torsion boxes -- that is, hollow core.

[Lee Schierer]

You can also make them "thicker" or stiffer by adding ribs of 1 x 2 material along the sides or underneath. The more ribs you add the stiffer the shelf will become. For super strong stiffeners sandwich 1/4" or 1/2" plywood between two layers of regular wood.

[Steve Schoene]

Check http://www.woodbin.com/calcs/sagulator.htm
It allows you to play with a wide range of materials and constructions to see what works and what doesn't.

I don't think there is any single wood material in which a 3/4" thick shelf could handle a 48 inch span, without changing the construction to fix the shelf at the back, or to add a significant front edging strip.

[Ray Schafer]

That webpage is not coming up for me? Does it work for you?

[Steve Schoene]

Try it now.

[Danny Thompson]

Norm makes some wide shelves out of 3/4" ply with edge-glued veneer. His solution was to double-up the ply, making a 1 1/2" thick shelf.

Google "Sagulator" and you'll see this makes a pretty robust shelf.

The general tips I have seen are:

- Add front or back edging. A good option is a rabbetted hardwood strip twice the thickness of your board. (The Sagulator now includes edging in its calc.)
- Add rear support. For example, if your shelf is supported by pins on the sides, make your back a little thicker (say 1/2" ply) or add a solid wood strip in the middle of the back and add a 5th pin there.