In construction, a ball and socket joint is based on a synovial bone joint, such as the shoulder and hip, in which one part of the joint is free to rotate to almost any angle with respect to the other part. A common use of ball and socket joints is in a steady cam, which helps reduce unwanted camera movements in film recording. Constructing a ball and socket joint requires some advance planning and preparation.
Cut the metal strips to the length you need the ball and socket joint to be, and file off any sharp edges.
Mark three points on the strip with a marker pen. One should be dead centre, the other two should be toward the edge of the strip, where the balls will fit. The exact position will depend on the size of the balls - place a ball on the strip, about 1/4 inch from the edge, and mark the point where the ball contacts the strip. Some metal strips can be purchased with pre-drilled holes -- if you can find a suitable part you can skip this step. The holes must be in exactly the same place on both strips.
Drill the centre hole using the drill press. The bit size used should be equivalent to the screw.
Use the thread tap tool to cut thread into one of the centre holes you just drilled, and screw the pieces together.
Drill the edge holes using the drill press. By screwing the strips together, you ensure the holes will be equally spaced on both strips. The edge holes should be sized to fit the metal balls.
Unscrew the strips, and on what will be the inside of the joint, use a slightly larger drill bit to widen the hole slightly. Do not drill straight through. Your goal is to taper the hole very slightly to accommodate the ball. Do this slowly and carefully
Use the file to remove any sharp edges from the metal strips.
Thread the metal rods into the threaded balls.
Position the balls in the two edge holes, ensuring the tapered side is on the inside. Screw the strips together and attach the bolt. Adjust the tightness of the screw to allow fluid movement, while securely holding the balls in place.
Wear protective glasses throughout this process
Tips and warnings
- Wear protective glasses throughout this process
Things you need
- Drill press
- Drill bits
- Metal file
- Metal strips/brass stock
- Threaded metal balls
- Threaded metal rods
- Screws, bolts
- Marker pen
- Thread tap tool