Pocket-screwed face frames
by Jon Elvrum
In this process, frame parts are brought to a drill tub where angled holes or pockets are drilled into the back of individual face frame parts. These holes include a pilot drill for easy start of the screw-together operation, which uses a pneumatic screw gun to drive the screws.
The assembly takes place on an easel table which varies in size from 4' x 8' to 6' x 12' standard. Each table is equipped with a rolling, clamping arm which moves from side to side across the table to position from 3 to 5 hold down clamps above the actual joint, where hold down clamps keep the pieces in place while the frames are screwed together. When all joints are screwed together, the frame is complete, and needs no other work.
When using a system where the hole does not come through the end of the frame part, the joint is secured by side clamping pressure, and the neck of the screw below the head is captured under pressure in hardwood. This allows the operation to eliminate glue from the jointing process.
When glue is not used, there is a significant labor gain resulting from reduced clean-up and secondary sanding.
Additionally, unassembled parts can be run through a wide belt sander just prior to assembly. Since the frames are assembled face down against the table, without glue or clamping of frames, secondary sanding can virtually be eliminated.
After a few hours of practice, the screw joint assembly system reduces labor in face frame construction by more than double, and reduces the number of personnel engaged in the the process significantly. Production by a single operator can be doubled easily, with more than triple efficiency not uncommon over doweled or mortise and tenon construction styles.
Jon Elvrum, Director of Distribution and Sales at Ritter Manufacturing in Antioch California, is also a well known author and consultant to the cabinetmaking industry. He has written numerous articles on the 32mm cabinetmaking system and production woodworking in general.
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