Finish carpentry is all about making joints quickly and accurately. To achieve that goal, our company relies on two specialized tools: a Kreg pocket-hole machine and a Senco corrugated-fastener gun.
A pocket screw is a self-drilling fastener that fits inside a specially cut mortise or "pocket." The mortise is created by running a pilot-tip drill bit through a jig that holds it at a shallow angle to the surface of the work. Later, a self-drilling screw is driven through this hole and into the edge of an adjoining piece, pulling the joint tightly together. The fastener is hidden inside the pocket.
Pocket-screw joinery was developed by Kreg Tool Co. We've been using Kreg's small portable jigs for nearly 15 years.A few years back we upgraded to a Foreman model, a stationary tool that makes the same holes a jig does, only faster. The model we have (DB110) is about to be discontinued but similar machines will remain available, the pneumatic version (DB55) of the tool we have now and a new less expensive electric model (DB210) that is supposed to come out late this summer.
With the Foreman, there's no need to handle a drill or clamp the jig to the work piece; you just butt the stock to the fence and pull the lever. As the lever comes forward it activates the motor, clamps the work against the table, and plunges the drill bit into the bottom of the piece. When the motor hits the built-in depth stop, you push the lever back and repeat the process for the next hole. This takes a second or two per hole — a fraction of the time it takes with a jig. For us, the labor we save justified the $800 cost of the machine.
The fence is equipped with adjustable stops that register the hole location from the edge of the material and can be rolled out of the way to make holes farther in, as is necessary with longer edges. Aside from speed and ease of use, one of the advantages of this machine is that it contains everything you need to drill pocket holes and is ready to go the moment you plug it in. Jigs require more setup, and in the rush to get to the job site it's easy to leave a necessary part behind.
The Foreman's motor is located inside the base and can be accessed for maintenance by lifting off the front part of the table. Maintenance requirements include lubricating the slides, adjusting the depth stop, and cleaning or replacing the bit.
On our jobs, we put the Foreman on a bench near our table saw and miter saw so that it's ready whenever we need it. We use it on just about any butt joint where the back of the piece will not be visible: mantel pieces, face frames, and especially wainscot paneling. We might also use it to end-join short pieces of baseboard, crown, and other running trim.
Pocket screws work well on a variety of trim products, though extra care is required when putting them into the edge of MDF. The screws will strip out if you overdrive them—which can easily happen when using an impact driver. We prefer to use corrugated fasteners (see below) to join MDF because it’s faster than using pocket screws and there is no possibility of stripping anything out.
A corrugated fastener is a ribbon-like piece of metal that, when driven across a joint, holds the pieces firmly together. It's most commonly used for industrial applications where strong, permanent joints are required — ganging windows together, for instance, and assembling the frames of upholstered furniture.
There are two kinds of corrugated fastener. The kind we use has ribs that taper toward the center and draw the joint together as the fastener goes in. Joints made with corrugated fasteners are so strong the only way to get them apart is to destroy the trim.
While it's possible to drive these fasteners with a hammer, it's far more common to use a pneumatic gun. We use a Senco SC2, though we could just as easily be using a tool from Duo-Fast, Spotnails, BeA, or Fasco. Our gun cost about $500, and while we don't use it every day, it has long since paid for itself: For the right applications there is no faster way to join trim.
Corrugated fasteners hold extremely well in MDF. We use them to join butts and miters from the back or from a side that won't be seen. They also work in wood, but they tend to split it when driven into or parallel to the end grain, which is why we use pocket screws for wood-to-wood connections. If I had my way I would make everything from wood, but the budget doesn't always allow that. Using MDF is a good way to save on material, and joining pieces with corrugated fasteners is a good way to save on labor.
This story is based on an article that originally ran in JLC.