Wood movement using cherry and secondary poplar

[Craig Parker]

I am designing a solid wood cabinet and have a wood movement question. I know that there will be about 1/16" difference between cherry and poplar in a 20" side and bottom. Can I glue and screw/nail the poplar panel to the cherry side or do I forget the glue and use only screws/nails? Or do I just use a cherry bottom which cost more than poplar?

[Robert LaPlaca]

The wood movement issue you are talking about isn't really an issue, that is because the Cherry sides and the poplar bottom long grain are running parallel to each other (if I am understanding your question).

When you would run into issues is say a poplar (or Cherry for that matter) drawer runner was glued cross grain ( long grains are perpendicular to each other) to your 20 Cherry side panel. In that example you need to account for the wood movement by gluing only at the front 4 inches and use elongated screw holes or nails on the remainder of the drawer runner.. Hope this helps

[Jim Matthews]

In carcasse construction, I use a web frame lattice.

The front (show side) of the carcasse gets the web frame screwed and glued in place.
The rear side (toward the wall) gets the web frame in a dado, such that the panel can freely expand.

The web frame, like your Poplar top and bottom panels should be inset in the Cherry side panels to allow lateral expansion.

Alternately, you can use nails alone to join them and the nails (provided they're fine enough) will flex a little with the seasons.

Screws and glue make for essentially fixed joints.

[glenn bradley]

If I understand correctly we are talking about a glued up panel of cherry 20" deep with the grain running vertically and a bottom glued up panel of poplar 20" deep with the grain running horizontally (grain directions essentially the same for both parts). My preference would be to use cherry for both and avoid the fussiness of accommodating different expansion rates (if the humidity swing in your area is that extreme). Cherry is not that much more than poplar given the amount of material you are talking about; even if double the cost the actual amount shouldn't be all that much(?). I look at the project and the time and money spent and then ask "would I do it all over again to save $20?". I find I ask this question primarily on hardware as some of it can be quite pricey. When I have a few hundred dollars in material and time in the mix already, it doesn't make sense to me to go bargain hunting. If you really want to go with the poplar, the traditional methods of accounting for movement in web frames and shelves should serve you well. They just seem out of place on a "bottom" panel. JMHO.

http://www.finewoodworking.com/membership/fwnpdf/011165044.pdf

[Craig Parker]

You convinced me, Glenn. I will use a cherry bottom. Thanks.