Attention To De Tail


The animal's tail.  It's thin and light.  It hangs at an angle away from the body.  Walking, it undulates.  Standing, it moves by itself, and it does so in absolute silence.  To do this properly in a fursuit, we're faced with a state of the art design challenge.  What you see below is my latest and best solution to this problem.

The undulating motion of the tail is a counterbalance to body movement, to steady the animal as it walks.   The laws of physics suggest that a counterbalancing effect can be done in a simple way with a series of springs and weights.  As the first weight is moved, energy is transferred by a spring to the second weight, and so on to each weight in turn, in a slow motion "crack the whip" effect.  Lighter weights and stronger springs move faster, heavier weights and weaker springs move more slowly.  In all cases, the energy is counterbalanced by being passed from one weight to another until it is at last absorbed by friction.

To build a physical analog, then, we need three things:   springs, weights, and support against gravity.

tail02.jpg (14780 bytes)

The weights are solid aluminum rods, 5" long by 5/16" thick.  They were cut from a single 4' rod (shown at the top of the picture) from Orchard Supply Hardware for a couple of dollars a foot.  I cut it with a hacksaw and smoothed the ends with a file, but you can use any method as long as the ends are smooth.

The rods are joined with 2" lengths of surgical rubber tubing, which I found at a local drug store for about a dollar a foot.   I chose the inner diameter for a tight fit so it wouldn't work loose.  Between the rods, held in place by the rubber tubing, are 5/16" diameter plastic spheres from TAP Plastics, for a few cents each.  These low cost universal joints are completely silent and almost frictionless, and shouldn't wear out anytime soon.

To complete the three requirements, a heat-bent piece of 1/4" Delrin rod provides both the spring action and support against gravity.  An 8' piece of 1/4" Delrin rod costs about $4 from TAP Plastics.  Delrin is an amazing material with many applications in fursuit design.  It's light, strong, springy and resilient in a very organic way, and is especially tough against abrasion (it was designed to replace cartilege in bone joints).  It heat bends at around 800 degrees F., then springs back to its new heat-bent position when cool.  And as if that's not enough, ordinary laminating cement makes it melt and flow, so two pieces can be fused together seamlessly.

The finished skeleton assembly is almost frictionless, so by itself it might wag back and forth unnaturally.  But not to worry, it will be covered with a fur tube and possibly a bit of padding, which will provide both stiffness and air friction to absorb the excess energy.

I know this is interesting, but the work is still in progress.   The tail construction isn't complete yet, so I'm not entirely sure that 5/16" aluminum is the right choice, but I can say that the Delrin is a definite success.   I'll post more results as the pictures come back, but in the meantime I must leave you with...


under construction -- more to come