When to use a center guide for a drawer?

[Roger Marty]

I see some traditional drawers that are fitted tightly with just wood-on-wood rails. Others supplement with a center rail. I presume the center rail helps to prevent bind-up. Can anyone comment on how strongly this is recommended?

[Jamie Buxton]

If you build a simple wood drawer running in a simple case, the case sides and the drawer sides must be all be parallel to get the drawer to slide smoothly. In fact, they should be parallel with just a smidge of play. If the smidge is too large, or the parallelism isn't perfect, you get troubles. Good craftsmen can make it work, but it can be a challenge. The center rail approach gets around the tolerance issue. You can make the case so large that the drawer sides never get near the case. The rail holds the drawer in position, and the tolerance issues are confined to how well the rail and the glides fit each other.

Now, if you're asking about recommendations, I say go with metal full-extension slides. (I like the Blum Tandems.) They let you pull the drawer entirely out. They slide more easily. They wear slower. They don't swell and shrink with the seasons. Use wood sliding surfaces only if you're determined to hobble your furniture.