Making Ball Joints

At each joint in the posable wooden maquette is a ball joint. This comprises a 12mm wooden ball fitted to a length of 6mm dowel. To this end, I need to be able to quickly and accurately drill a 6mm hole into a wooden ball.

Here’s the jig I’ve come up with.

I’ve drilled a 6mm hole into a piece of 2″ x 1″ and countersunk it. This will be where the ball sits. I’ve then cut out four pieces of 3mm ply on the laser cutter with the top piece over hanging. I’ve screwed them down to the 2″ x 1″ so that their edge is 40mm from the centre of the hole.posable-b02

Here is the jig with the ball sitting in place.posable-b03

The clamp piece is another rectangle of laser cut ply. It has a 10mm diameter hole cut 40mm from the edge.posable-b04

The clamp works with simple finger pressure to hold the ball as it is drilled.posable-b05

I’m using a pillar drill for accuracy. Step by step:

Lower the drill to line up the jig with the drill bit then clamp the jig into place. (Clamps aren’t shown on these pictures)posable-b06

Raise the drill, fit the ball and clamp piece.posable-b07

Drill down into the ball. Quick and accurate!posable-b08

Sample balls and dowels.posable-b09

Having worked out how to make accurate ball joints I’ve been working on the maquette. Latest step, I’ve added body, shoulders and neck. Looking good so far!posable-b11 posable-b10

As a quick try out, I’ve added a spare leg onto the shoulder, the actual arms will need to be smaller and thinner but you can see the effect.posable-b01