Fastening the Pieces

Another advantage of MDF is how easily pieces can be joined together. Regular 2-inch drywall screws should be sufficient to hold moderate weight loads. Using wood glue as well as screws will be even stronger, while biscuits and glue will produce the strongest joint (but you will need a biscuit joiner to cut the slots for the biscuits). When using screws, first drill a pilot hole for the shaft and a countersink hole for the head.

Before attaching any fasteners, however, dry fit the pieces of each section together to make sure everything has been cut to size. Attach the sides to each other first, then add the shelves. Fastening shelves will be easier if you set them on two temporary spacers to hold them level while you drive the screws. If you plan to set any heavy objects on the shelves, you should plan to add additional support pieces in the middle of the lower shelves, as Ty did in the unit he built.

Finishing MDF

If you used glue, clean off any excess with a rag before it dries, or scrape it off after it hardens. Fill the countersunk screw holes with wood putty. Sand any rough edges, and remove dust from the surface with a tack cloth. Apply an oil- or shellac-based primer to the unit. When dry, sand the surface lightly. For best results, apply another coat of primer to at least the edges of the unit. Sand again, then apply two coats of oil-based or latex paint.

Let it Roll

If you want to add casters, plan to attach at least three to the bottoms of each section. For larger units, and especially for units that will be holding quite a bit of weight, you may want to add a fourth caster. Casters can be fastened to the bottom shelves with bolts and nuts. Attach them as close as possible to the edge so that they are positioned under the weight-bearing sides.