In a through feed molder, each tool is mounted to a slide and provided with a dust hood that also carries two conventional hold-down guides, rigidly attached, one on each side of the hood. A mechanism operating between the hood and the slide permits matching of the clearance between the hood and the horizontal bed of the molder to a given tool reference diameter. The hood is also interconnected with the bed by a measuring device which verifies the clearance of the entire tool assembly according to the thickness of the work. Displays are used to indicate the tool reference diameter and the distance of the hood from the bed.