IDLE HANDS AT THE TEAT OF INVENTION

Last modified: Saturday, January 6, 2001 6:20 PM

 


"...Pump it up... " -- Elvis Costello

True story, from Dave Plesic:

"...there was a toy my sister had called Growing Up Skipper, that later proved to be a scandal for Mattel. Basically, you raised one of skippers arms over her head then cranked the other arm several times. The result was the doll growing 1/4" taller and BREASTS. No kidding, skipper grew little breasts..."

Dave created this diagram, essentially a recreation of the infamous & clever mechanism, inspired by the tensioning screw of his chainsaw. (!)

Wow... Thanks Dave!

 

zatoichi doll

Yojimbob Meets Zatoichi

or

Got A Joint?

Many of the figures coming out of the Far East these days have lots of articulation, allowing them to assume poses that the good old vintage Joe isn't up to. Some of this is due to the addition of more joints, and some of it is due to the use of different combination of joints. I don't know the technical teminology for these, but this is what I call 'em:

A hinge joint is two interlocked parts joined by a pin, usually starting and ending within the same piece, so that the joint is reinforced in its alignment. This allows movement on one axis, and the pivot angle is limited by the clearance of the two parts joined by the hinge. If you connect two hinges together along the same axis, you can achieve a 180 degree pivot angle. These are used for things like the elbows and knees, wrists and ankles.

A swivel is like a hinge, but simpler, with only one point of attachment. Because the parts aren't interlocked, they can clear each other, and a 360 degree rotation is possible. A swivel may be limited in its range of rotation by extending the parts to block each other. If you connect a hinge and a swivel together at a right angle, you approximate the function of a ball joint. The head rotation is an example of a swivel.

A ball joint allows movement on any axis, but the pivot angle is more limited because the ball has to be retained within its socket housing. A ball joint may also rotate within its housing. Ball joints are usually used at the shoulders.
zatoichi doll This particular figure (a 12" Zatoichi figure) has a combination ball and hinge at the hand (A). The hinge is familiar, but the ball joint allows the wrist to pose at a slight angle in addition to providing the standard rotation. (The seam at the hand doesn't do anything; it's a joint between the two different materials.)

The elbow (B) is similarly articulated, but the extra cut into the upper arm allows the ball joint to function like a hinge. So in that one position, the elbow is articulated like a double hinge, which allows for a very acute bend. Note that because the ball rotates,it replaces the function of the bicep swivel found on vintage-style Joe bodies.

The shoulder's construction (C) is similar to the wrist. The ball in this case allows a small angle of forward-backward-upward-downward posing, in addition to providing the rotation.

The hip articulation (D) differs in that there is a hinge and a swivel, linked perpendicular to each other. This permits the legs to move forwards and backwards and to spread, but unlike a true ball joint it does not allow each leg to rotate within a socket. This means that the knee joints must face forward if the legs are aren't spread apart. However, the figure can sit cross-legged since the knees have double hinges, which allow a very sharp pivot angle.

zatoichi doll dissected This picture shows how the figure's articulation works. The torso ball joints & head are held in tension by springs. Also notice that the shoulder's ball joints are held under compressive tension by the two halves of the plastic socket. How tight the balls are held depends on how tightly the two body halves are screwed together.

It's easy to be seduced by the dazzle of lots of articulation. But quantity is one part of an equation which also should take wear-resistance, maintenance and appearance into account.

Appearance factors into this because it's at the other end of the trade-off: As you increase the number of joints (and screws), you sacrifice the figure's "realism". In addition, the articulation may require large openings and peculiarly-shaped areas for the components to function with adequate clearance. Although clothing can hide most articulation, concern for appearance may affect which clothing the figure should wear. A figure with a huge articulation seam running across his chest should not go around with his shirt open! In a well-designed figure, an attempt should be made to minimize or conceal the ugly artifacts of manufacturing necessities if possible.

Wear resistance and ease of maintenance are important issues to me, since I hate built-in obsolescence. This is where I'm disappointed by many of the modern designs. The "Classic Collection"-style bodies are among the worst offenders in this regard, since you can't repair them unless you want to take extraordinary measures-- they appear to be designed for ease of manufacturing and to comply with USA child product safety laws. Even these new super articulated figures suffer from this to a lesser extent, but for different reasons. Although they're extremely user-accessible because of their screw assembly, they suffer from the problem of being too complex and finicky. Consider the ball joints: In time, wear will loosen these parts within their sockets, so it will be necessary to add extra frictional material to line the sockets. (Knowing how much lining to add would be guesswork...) The socket halves are screwed together and need to be held together under considerable pressure-- this pressure is borne by the screws and the plastic threads which secure the screws. Repeated reassembly will weaken these fragile threads and they'll need to be rebuilt (metal thread inserts would be better). The elastic-tensioned ball joints of the vintage figure are a more durable design for major articulation, since they're self-adjusting and easy to maintain. Their weakness is that they provide a more limited range of movement, particularly at the unslotted ball joints at the torso/hips/legs. This means that the figure can't make the necessary hip-thigh bends for the figure to sit properly.

The hinge construction is a different problem. Here, there aren't very many options available to ensure that a hinge stays tight. Metal rivets seem to be an adequate solution, since they can be recrimped. Screw and nut assemblies may be slightly better since they can be more finely adjusted. The addition of a compression washer might improve this even more. What doesn't work well are plastic or rubber pins, since those hinges rely on the frictional forces between the materials that the hinges are made from-- the pin itself only serves to hold the pieces in alignment. These hinges can't be tightened and severely limit the amount of weight that the hinge can support.

As you can see, there is no "perfect" solution, only compromises.

 

zatoichi doll "No. I prefer a pipe."

The Zatoichi figure was released to honor the Japanese actor Shintaro Katsu (1931-1997), and his most famous role as a blind beggar/masseur/master swordsman. Many of his films have been subtitled in English (but may not be in current U.S.A. release).

A Toshiro Mifune ("Yojimbo") figure is planned for release in the near future.

 

A COMPROMISE?

This body design combines what I consider to be the best features of the various body designs: the easy-to-maintain reliability of traditional elastic-tensioned ball joints with the wide-range poseability of articulation found on modern figures. It's a restrained approach-- evaluating the drool-inducing benefits of mega articulation through the filter of practicality. So this is a simple design, essentially a modified vintage design. Compression-tensioned ball joints were nixed because of their potential maintenance problems, on the principle that the minor bit of extra articulation wasn't worth the problem of floppy joints.

The extra upper torso articulation was added because it helps alleviate the problem of the figure sitting, albeit in a natural "slouch-backed" position. But it also permits more dynamic & and natural poses, approximating the human spine.

The double hinges at the knee are a good idea which don't require any compromise. These work well with the hip's ball hinges because the balls allow the rotation of the knee's fixed axis to any position.

The elbow hinges were more difficult (and aren't illustrated properly here to reflect my re-thinking). Double hinges would be preferable, but then the bicep swivel would need to be a separate joint (something I originally wanted to eliminate for aesthetic reasons).

The "peripherals"-- neck pin, feet & hands -- are all left as standard forms of attachment. It would be great if these were standardized. That way, one could replace feet to match the size of the variety of footwear that you find out there, or replace them with more realistically-sized "footshoes".