Im about to start making an armature for my stop motion puppet and was wondering what type of screws you guys use in your ball and socket joints and where I can get them (I live in Sydney).
I was also wondering about your opinions on mild steel vs brass for making the sockets just because I've read that brass can bend slightly when the socket is tightened.
Most commonly used screws for joints (and what I use as well) are 'socket-cap' machine screws. But, I've also seen regular flat head and cross head screws as well as 'set screws' which gives a nice flush appearance, but makes it a little harder to find if you ever need to tighten the joint. I find the material of the screw doesn't really matter, I often just use some variety of steel as it's the most widely available and cheapest option. I cannot offer much as far as where to find various screws where you are, but I know others on the board can offer some suggestions.
The question of mild steel vs brass is a bit broader of a topic as both have their own advantages. I know others on the board will give much more detailed responses, but I'll just start with an overview of each.
Beginning armature machinists often lean towards using brass for joints. Of the two it's the easiest to machine. With proper technique you can build a complete brass joint with just a dremel and drill (plus assorted miscellaneous clamps, bits, etc.). It is true that if your brass stock (and true of any material) is too thin it can bend. The problem is that that thickness is surprisingly thick. Sven Bonnichsen wrote extensively on armature machining on his blog Scarlet Star Studios. There he mentioned that the minimum thickness of brass stock to prevent flexing was about 6.5mm depending on the length and type of joint.
Steel is a much greater beast to tackle, but still manageable provided the right tools are used. The strength of steel offers much greater flexibility in terms of the size of the joint that can be made as well as type of joint (ball and socket, step block, hinge, socket, etc.). The joint plates can be made much thinner than what brass would allow for, which lets you build smaller joints. The down side to machining steel however, is the process. It takes a lot more tooling to tackle even mild steel. And some types of joints require additional tools to produce. And additionally depending on the location, buying steel stock is often less expensive than brass (I'm not sure about other places but where I'm located brass is about 3x more expensive than mild steel).
I highly recommend reading Sven's blog posts on armatures for lots of fantastic information. There are also a handful of threads on the forum here that may be useful as well.
Hope that's a slightly helpful start!
thanks, thats exactly what i needed
it depends on how big and and how complex your armature is.
peasonally i like stainless steel screws. they are tough instead of soft like mild steel. and not much more expensive. they wont rust either.
brass is tougher than you think, if you dont braze\solder. as the metal is annealed easily and becomes too soft. brass can also hold a thread well, easy to tap, file etc...your tools will last longer