Working on some swappable sockets, need some ideas

[red5angel]

Hey guys I've got some ideas for some small swappable sockets for various models, something to let you plug in modular pieces, but I need to locate some material to work with to see what's possible. Initially it's either a simple ball and socket concept where the ball is a soft plastic tip that can be squeezed into the hole or a soft hole that would take the tip and hold onto to it fairly tightly.

[TER-OR]

Headphone/microphone sockets are great for this. They've got a spring inside which provides a positive click. You can even use them to provide power to a model!

[naoto]

http://www.hlj.com/hljlist2/?word2=ball ... Maker1=WAV

[Chacal]

...or a soft hole that would take the tip and hold onto it fairly tightly.

You said it!

Joking aside, how big and heavy are the swappable parts to be? Do they have to be mobile (like an arm or cannon) or fixed in one position (like a weapon hardpoint on the wing of a fighter plane)?

If the parts are heavy and big you can use small locator pins (most likely metal) and magnets (neodymium). The holes for the pins can look like a modular mount, so without the attached parts the model will look "complete", and the metal pins are what the magnet(s) inside the model will pull.

[red5angel]

wow, didn't know someone actually just made ball sockets!

Chacal, the weight isn't an issue really, its mostly size, the size of these parts will be on the small side, a centimeter or two long at most.

[tetsujin]

wow, didn't know someone actually just made ball sockets!

Better believe it. When you want to know about parts for modularity or posability, ask a Gundam modeler.

There are some potential problems with using ball joints for modular assemblies, however. First off, most ball joints are the latter variety you described: the socket is flexible and holds tension, while the ball is hard. This means that wherever you mount the socket has to allow for some "give" for when you plug in or remove the ball - otherwise, in some cases, inserting or removing the ball from the socket can press outward on the halves of your part from inside. In some cases that can be a bad thing - depends on the construction of your part. Ball joints IMO are better for posability than for modularity.

For modularity I'd recommend regular polycaps: like these or these. They go well with metric styrene rods sold here. The disadvantage for using axial polycaps for modularity is that they tend to have a stronger friction lock than a ball joint would - a ball joint would have a bit of a threshold at which the joint would "pop" apart, but an axial PC would simply resist the force that pulls them apart or pushes them together, and a few of them in parallel can make the resistance considerable. The requirement for precision is also greater when working with the axial PCs, since to pull things apart again when it's held together by multiple PC joints requires that all the joints be set up parallel.