Armature Build – Part 1

I’m building a ball-and-joint armature for the detective character (designs here). The build has gone quite smoothly so far, and I’ll be posting more images as things progress. I’m hoping to be almost finished by the end of the week and on to the sculpting/casting phase of the character build. For an explanation of what’s going on, each photo will have a detailed caption included. I didn’t take as many photos as I probably should have for a true documentation, but I’ll post what I do have. Ask questions! I’ll probably answer them.

I took two identical bars of 1/4″ brass bar (K&S brand) and clamped them together horizontally in a vise and then vertically with a 1″ C-clamp. A 3/32″ hole was drilled 3mm from the end of the plates. Use a center-punch to get a small indent for the drill press to ‘find’ before starting.

The hole is then tapped using a 4-40 tap. Be sure to go slowly and turn the tap at least one quarter turn counter clockwise for every 1-2 turns clockwise to release the cuttings or you can snap the tap.

Screw in a 4-40 socket-head cap screw into the newly threaded holes. This will keep one end of the bars together. Repeat all of these steps on the other end of the bars.

When you have both ends threaded you can mark out where you will be drilling holes according to your particular armature design. Then you will clamp the bars in the vise again.

First you will drill a pilot hole for every mark you make where holes will need to be drilled for your armature. Do this with a 1/16″ drill bit. Be sure to work slowly and use cutting fluid. You’ll break bits, don’t get discouraged, just remove the broken bit and try again.
Then expand all the holes to 3/32″. Next you will expand only the outer holes (the holes that hold balls in your armature) to 11/64″. The holes for screws (marked with a circle in Sharpie) will stay 3/32″ for now.

Once these holes have been drilled you can separate the two plates and finish the top plate. Expand the screw holes (on the top plate only!) to 1/8″.
Then move to the bottom plate and tap the screw holes with the 4-40 tap to give the screws a thread to grip.
Now you can mate the plates together again putting a screw through every hole you drilled and tapped.
Now place this in the vise again with enough sticking out to do some cutting! Hold one end with a helping hands device (not your fingers, it gets hot!) and cut off at the marker lines with a Dremel tool. Make sure you use reinforced cutting wheels. Alternatively you can use a hacksaw, but a Dremel is a bit faster. Carefully shape the ends of the joint you just cut off to a rough curve and then finish the ends using a metal file.

Here is what your joint will look like with the bearings (or brass beads) inside after all the holes have been drilled and the bars cut to size and shaped for aesthetics (and comfort, no jagged edges to catch your fingers on!)

In part 2 I’ll be soldering the brass rod onto the brass beads to make the barbells that get placed in the joints so the armature can start to take shape! I might try to get a few more pictures of the joint shaping process, but it will depend on time. Stay tuned and thanks for stopping!

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