Hi guys 
Here is my attempt at an Alien Facehugger. Pretty new to learning about animatronics and made a few mistakes but hope you like him 
http://youtu.be/jw9RVW5qvHc
http://youtu.be/xhkfvxm0Iv8
http://youtu.be/YrE0pBEo2Pg
http://youtu.be/tAes3m6jTko
----Metal Maquette Leg
After fabrication of the initial plastic leg
maquette it was essential to produce a metal maquette to test the fluidity of
movement with the added weight and source the various materials that would be
fit for purpose. Initially one
pivot point was produced to ensure the various metals would be not only strong
enough but also bond well to each other.
Brass stock was used to create the top of the ‘knuckle’ pivot point with
steel coated in zinc utilized for the hinge stand offs, pipe clamp, nuts, bolts
and spacing washers.
Technical
Issues
At this stage there was a major technical issue
with regards to attempting to solder the brass stock onto the zinc coated
steel. Some brass stock
immediately held strong after plating the steel with solder, however, other
pieces were extremely brittle and loose causing the metal joint to hyperextend locking
the joint into an extended position.
Aligning the cable supporting disc when using Lock Tite was difficult to
attain due to the position of the nuts when tightening in place. Metal burs and sharp edges caused some
fraying on the return elastic after approximately 200 bends of each joint.
Design
Modifications
After using several various flux and cleaning
routines the decision was taken to still solder the brass stock into position
and add a small pipe clamp to ensure there was absolutely no movement when the
model was being pupeteered. The
control cable was placed in position to ensure correct alignment of the
supporting discs and all sharp edges and burs were filed down to a rounded
edge.
Result
The resulting action from making all the
relevant modifications was a correctly aligned cable run, a reduced risk of
rips and tears in the outer skin and return elastic and a greatly reduced risk
of the brass stock coming loose during operation.
------Chassis
Design
Technical
Issues
The type of metal utilized taking into
consideration strength and weight along with workability during fabrication,
the chosen metal was mild steel.
To achieve the desires angle of the protruding legs the steel had to be
scored initially with an angle grinder which was effective, however, the metal
became very brittle as it was bent into position whilst it was too hot and
snapped.
Design
Modifications
The decision was taken to allow the metal to
fully cool down after grinding and not scoring too deep in an even line.
Result
The end result was a much stronger angle bend
that stayed in position to support the legs.
------Hand Control Mechanism
One hand control framework was assembled
without solder and tensioning cable return was attached to check fluidity of
movement prior to attaching the rest and finalizing with crimps.
Technical
Issues
Whilst soldering the brass tubing the cable
housing became too hot preventing the cable moving freely therefore limiting
the overall movement
Design
Modifications
The decision was taken to dissemble the thumb
trigger mechanisms by de-soldering the joints to remove the cable housing
exposing the bare cable then re-attach.
Result
This modification resulted in a cable that
moved freely within the pipe.
-----Leg Fabrication
Four steel discs per leg were initially
required to support the return elastic and cable run. This disc required subsequent holes to be drilled in one as
a template then accurately drilled out using the drill press. Brass stock was cut into strips and
supporting tubes were also cut, flux was added and soldered into position to
enable the return elastic to be attached. The flux was removed with a damp
cloth. These were then soldered
onto the steel hinge stand offs and further supported with the addition of a small
pipe clamp. Steel
threaded rod was measured into the desired lengths for each leg segment and an
angle grinder was used to cut them accurately, removing all burs with a hand
file.
------Chassis Fabrication
A scale cardboard template was used to
achieve the correct shape in the mild steel. Using an angle grinder the metal was scored allowing it to
bend into the desired shape and angles to receive the legs. Unnecessary metal in panels were cut
into the bottom of the chassis to alleviate some of the weight. Holes were
drilled into the sides of the chassis ready to receive the bolts from each leg.
-----Hand
Control Mechanism Fabrication (Peter Weir Clarke's Very Cool Hand Control Design Tutorial )
Copper pipe was measured and cut into
the desired lengths using a 15 mm pipe cutter. L and T shape and copper fittings were used to achieve the
correct shape and bespoke length. Holes were measure into the middle and top supporting pipes
prior to soldering and holes were made to receive cable tensioning mechanism
housing brass stock. The
brass stock was cut into adequate lengths and placed into the pre-drilled holes. Flux was then
added to the pipe joints and brass stock housing and placed on block to be
soldered into positon. All flux was removed using a damp
cloth and the brass stock housing was cut flush with the copper pipe using a
Dremel tool. All metal burs were
then removed with a small hand file.
Brass stock two sizes below the brass housing
was cut into the correct lengths and cable was passed into the pipe and
returned back through to create a finger loop. These were then fed into the housing
and two compression springs per finger was added to assist with the cable
return. Locking nuts were added to
the pipe to prevent the springs sliding off and the cable was crimped into
final position. Cable was then fed
through the top copper bar pre-drilled holes crimped to the existing finger
control cables under slight tension.
------Outer Skin Fabrication
The mechanism was clayed up
to achieve the desired shape and texture. Three trials were undertaken to create
an effective skin shell with an adequate negative space for the mechanism. The
final shell was produced with a simple latex slush mould that was used to
create liquid latex sleeves and very thin nylon tights were added to increase
the overall durability. Nails were produced using mouldable plastic Coolmorph and the entire leg
was airbrushed, building the colour up in thin washes to achieve the desired
colour and shading. The nails had
three coats of nail varnish added for extra strength and effect.
-----Tail
The main tail internal
support structure was formed using high density pipe covering foam, shaved into
the rough shape and covered in Le Beau Touche clay to achieve the desired form,
shape and detail
Hope this helps