Sunday, August 1, 2010

Testing Knee Joints




The main reference I am using for testing and making ball joints is Zen and the Art of Articulating Dolls by Using Balljoints by Twigling, Copyright (cc) 2007 Therese Olsen.





I do not own a ball-jointed doll, so it is a real mystery to me how the stringing and ball-joints in the sockets feel. I don't have any way of knowing what the tension is, or how a doll is posed, or anything. I'm only familiar with what I've seen in images and videos online. I will learn about all of this stuff with this doll. I'm currently thinking about how the knee joints work, so I made a test knee joint from brown microcrystalline wax, using the plaster mold I made earlier, of the upper leg.

I cast two wax legs.






I worked on the small end of each leg. On one leg I cut off the ball. On the other leg I cut a hole and a slot.






Then I cut a hole in the center of each of the large balls.






I don't have any round doll elastic yet, so I used a long rubber band to string the test legs together. Together, the test legs are 290mm in length. The rubber band is 3mm wide, 1.5mm thick, and 370mm in circumference. I made a stringing tool from a piece of coat hanger wire, with a hook on one end, and a circle for a handle on the other end. The ends of the rubber band were put around two pieces of 5mm dowel at each end.






Now I can see and feel a little bit about the behavior of a strung ball-jointed knee.






I will use this test knee joint to build up a knee around the joint, to see what I'll need to do with the BJD I am making. It may not be the best way to do this, but it is much better than nothing.




Later the same day...



The test knee built-up, strung, and flexed.





The test knee straightened out.





The back of the straightened test knee.





The test knee partially flexed.





A closer shot of the slot with the rubber band on the test knee.





Another view of the test knee and the rubber band.





The final shot. Note that no paraffin was added to the melt for this test knee. The wax is unmodified.






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