This is going to be a monstrously long post so you might want to get comfortable.
In this post I'll be demonstrating how to make a ball and socket joint. Its quite a complex process so bare with me.
Ball joints are a more advanced method of making armatures. Unlike wire armatures, ball and sockets joints can be manipulated over and over again without wearing out and breaking. Another positive it that individual joints can be loosened or tightened to your desired tension. The down side to using ball joints is that they are time consuming and complicated to make. In the past I've made ball joints out of brass and used them in the necks of my puppets.You can read about my old ball and socket joints HERE.
I plan to make new armatures for the characters 'Roy' and 'Elle'. This will hopefully give them a greater range of motion and I won't have to worry about wearing out the aluminium wire armature. I plan to achieve all the articulation with an mix of steel ball joints and hinges. I'm quite confident that my home made ball joints work, the challenge is making them small enough to fit inside my characters.
If you want to see some great examples of ball and socket joints then I'd recommend John Wright. His ball and socket joints are super high quality and used for many professional productions. John Wright Ball Joints can be found HERE.
Tools & Machinery
Here are some of the tools that I will be using. Firstly a bench drill press. I recently invested in this specifically for making ball and socket joints. Its quite small so it doesn't take up too much space.
Above you can see a small vice I use for holding materials while I drill. Its screwed into a small wooden base so I can move it around while I'm working.
Finally, I use this rotary tool quite often at various stages. I have a collection of accessories that fit into the tool. pictured above is a reinforced cutting wheel.
I start by making the plates that will hold the steel ball bearing. The size of the materials will vary depending on the size of the joint. Here I'm making a 5mm joint.
I started by cutting 2 small identical lengths of steel bar with a hack saw.
Its easier to make the plates in batches so I've marked one of the bars to show where it will be divided. I will be focusing on the left section.
When I'm happy with the positioning of the holes I use a center punch to put a little dent into the steel. This acts as a guide for the drill bit and locates it to the right spot. Without the center punch the drill bit would skate on the surface and drift off course.
Drilling & Soldering Ball Bearings
Now that the plates are ready the next stage is to drill some steel ball bearings to go in them.
Next I expand the dent using a 1mm drill bit in the rotary tool.
I then drill the bearing using a M1.5 HSS drill bit and the drill press. I once again drill in short bursts. I try to drill about 60% of the way through.
Finally I check to see if the steel rod fits. If the hole is too shallow I drill some more.
Next the ball bearing needs to be soldered onto the steel rod. The join needs to be really strong as the ball and rod will be under huge pressure when secured in the joint.HERE
At the bottom of the picture is a small butane torch that's used for heating up the metal and melting the solder. Finally you can see that everything is laying on grey brick. This acts as a heat proof surface that I work on. I don't want to burn down my desk.
I then applied flux paste into the hole of the bearing and onto the end of the steel rod. I pushed the two parts together and used the helping hands to hold the parts on the surface.
The bearing will start to glow a cherry pink. Once this happens I dunk the ball into some water and quench the heat.
After drying it down it should be cool. You can see in the picture above that the metal is darker and has fire scale on it.
I use some wire wool to clean of the dirt and shine the bearing up. Now that I've completed the first ball I repeat the process to make the second ball.
I will be using this kind of ball and socket joint for the waist of my new armatures. Using these basic methods I will be making several different joints and I'll post details about them soon. I will probably continue with hinge joints.( Hopefully it will be a shorter post)
I hope people find this useful.
Thanks for reading.