Prop Tarantula Leg Connector Component Development

Problems with Original System

Flexible joints made of hare curlers and 3mm garden wire encased in duct tape pushed into the pipes.

The connection to the body was to be on a board that formed the centre of the head with 45 O degree plastic pipe connectors bolted to the board with two holes cut through. Small for the bolt, big for the head then another set of holes to pin a 5mm bolt though the pipe.

The problem here was said connectors started with being weak thin and fragile. The holes for the bolts and bolt heads removed about 1/3 of the plastic. This left a very thin surround of said holes.

On top of this these connectors were round. The board the connectors were to be attached was flat. This mean they did not sit flush with the board, in fact had very little surface area which was further put under strain with a bolt inside crushing the plastic structure.

Thus, these simply were cracking and breaking in large numbers rendering them useless and that’s before any weight was added or forces from the legs holding up the board let along a full head of material and other legs.

In addition, what did not see to be a problem was that when it was just a board both sides could be easily accessed with the use of wing nuts on the other side.

Later this was to be fully encased in the foam that made up the body of the head, thus pretty much inaccessible without octopus like tentacles whilst damaging the foam head.

Clearly not practical so other solutions needed looking at.

Concept Ideation

Proving Principle Prototyping

From sketching moved onto proving principle prototyping PPP, looking into a system of slotting onto the side of the base board using foam board Proving Principle Prototype.

This proved structurally far stronger.

With foam PPP testing the banana shaped connection system seemed to work out the best with half the estimated material needed for the universal fit.

This one could be adapted to a downward pointing connector for the for legs with a slight adjustment to flip the position for the square bolt.

CAD Development

Taking what was learned from the sketch ideation and foam board prototype testing then moved onto CAD development for rapid prototyping on Solidworks to create the first 3d printed prototypes on my Raise 3D N2 3D printer.

A more rounded form was created to look more organic but this did make it harder to hold in place for post - production work in vices.

At least 10 versions were produced.

The first few were primary being tweaked to fit the additional components better like the leg pipes. At first the shaft was too tight then too loose. Similar situation for the metal washer slots and bolt holes.

At first the bolt holes had a screw thread tap designed into the STL files in photoshop. Then with a tapping wrench before What was found was that this took too long for the bolts to be screwed in, too tights and also being a soft PLA plastic very soon wore out within a few insertions.

Thus, the holes were widened to be a 1mm then ½ mm to just let the bolts slip though where they went through the shaft and though half the board holding end before switching the board holding wing nut for an embedded square not to be superglued in place after 3d Printing. The nut enabled fighting enough to hold the connector in place but just loose enough to swivel to pose a leg

The square nut being chosen over hexagonal as less likely to work loose through torque.

Other iterations pushed the shaft further out and at a more acute angle to the legs would be more vertical.

More to try and minimise the material to lower cost and speed up the 3D printing process.

The swivel curve was made more triangular, sides rounded off the increase the swivel range , slots added to pivot to reduce material & build time.

It needs 1-2mm wire reinforcement running from the washer slot base board attachments to the other side to deal with sheer forced due to extra spider weight in furture developments. This is also due to the 3D printing process in layers. Due to all the over hangs & gaps this can only be done vertically which means these are weak right at the angle of the sheer forces which can snap the base board joins off. This would be glued in place.

Primary Instruction Video to Start With

This video by a Paul Jones was initially followed quite closely or attempts to were. It looked realistic, intimidating, A seemingly good size and looking at the material listing seemed doable for a rough budget of just over £100, with easy to acquire materials and doable in a week to couple of weeks.

It was only when construction started that it became evident of missing steps in the video and complete underestimating the amount of material and time that would be needed.

The system to connect the legs needed substantial improvement and resulted in the development of these connection components.

Spider
Title & Intro

Page

This was a double bed size prop Tarantula, originally intended as a cool Halloween front of house prop as well as portfolio piece to discuss project development.

Finished project page.

Spider Project

Development

Projects Accounting Costs

Spider Initial Research & PPP Testing

To start the project was looking into existing props and Halloween tableaus and how such a project could be done.

Initial Proving Principle Prototyping & scale modelling.

Spider
Development

Head

The main central part is the head to which all other parts are connected and would be the section to connect stands and load supports.

This involved the most substantial development and most restarts.

Spider
Development

Body

This had a similar basic structure to the head but a lot simpler. It does have its own issues and problems.

This had to be re-opened for upgrades to strengthen the connections to the head.

Spider

Development

Legs

The legs required repeated and costly redesign and rebuilding building to try and build enough strength into them to be able to support the weight of the spider, as well as look realistic and bond the paint to them.