Friday, 24 March 2017

Making a basic eyeball mount and mechanism for a dummy head

Here is the first look at the eyeball mounting for the dummy head I am building. It is being finger operated directly on the eyeballs here. Eventually it will have an mechanical interface so that some sort of operating mechanism will move them remotely.

This is what it looks like from the back. It has two metal plates. The large one at the bottom is the main mount. It has a hole to receive the shaft of the vertically mounted eyeball spindle. 

For each eyeball, the lower spindle locating hole is centred within a semi-circular gimbel that is the mount for an eyelid. There are upper eyelids.

At this stage the eyelids have separate controls. These are the levers.

And the eyeballs move on these vertical spindles. They can only move left and right, not up  and down. For now, they are not locked together either.

To make these took a bit of thinking. I looked at a few ventriloquist dummy mechs online which were enough to get the basic idea.
I then needed to draw out a basic design that I could build...

Here are the scribblings where I was trying to visualise the way they would work.

And a close-up of one of the better worked-up drawings. This one is thinking through the use of a parallelogram-shaped frame, so that a single centre rod could move both eyes.

Here is a three-quarters version that is a revised look at this.

Making eyeballs

The design for the eyeball mount was based on a vertical spindle. The first thing to do was find some spindles. Luckily I hoard things like old oven grills in case I might need them for making stuff.

Amongst these, I found this grill

From this, I cut off some of these sturdy spindles using a saw blade in the multi-tool

To fit these I just needed to drill some holes in the eyeballs I was using. These are the balls from roll on underarm deodorants.

Here you can see the rather dubious hold-it-in-the-hand technique

Once drilled, the eyeballs were kebabbed onto the spindles thus...

Here there are resting in the hollowed out eye sockets in the back of the face mask.

There's a bit of a Cyberman vibe going on here.

This is the front with the eyeballs in place but the spindles removed for now.

Making the mounting plate

This shot shows the lower plate and its two semi-circular mounts for the two eyelids.

To make this from steel is not easy to guess, so I had made a paper prototype first.

This is on the right

To work out how far these needed to be apart, I had previously measured the distance between the centres of the two eyeballs in the neutral position.

I also needed to work out the length of the eyelids. 

I made further prototypes for the eyelids from cardboard tube like this...

The eyelids just need to be strips. Here is one freshly cut from the cardboard tube.

Here it is being tested.

Slightly closed for a dopey look

These paper models were all I needed to work out how big the eyelids needed to be, then cut them out from steel plate.

I then had to mark out on the plate, the length of the equivalent gimble (the corresponding upwards curved mount to which each eyelid would be attached.)

It's hard to see here, but the 60mm distance between the eyeballs measured earlier is shorter than the 70mm needed for the gimble. This is why the plate needed to be folded.

Cutting out excess metal.

Beating in the centre fold into the sheet

Halfway folded...

Using the vice to fold the plate fully.

From another angle.

And swapped upside down.

And finished off with a damn good beating on the anvil.

The finished centre fold.

This was tight, but needed to be opened out. A crow bar was easiest

And the flaps beaten out. Th

And the gimbles cut out with the angle grinder

The distance between the centre of the two gimbles is 60mm, to match the distance measured earlier between the eyeball centres when positioned in the mask.

These flaps had been cut out with a metal cutting blade in the reciprocating saw.

The flaps were shaped using a hammer head as a former.

Paper prototype recreated in metal :)

The eyeballs needed a top plate to locate the shafts.. This is just a bit of folded aluminium drilled and fixed.

Seen from the front.

The metal eyelids were fitted onto the gimbles using rivets. These were not fixed too tightly, to allow them to act as hinges.

Here is the face with eyeballs in place (with irises drawn on for testing)

Eyeballs open...

Eyeballs half shut...

Opening again..

Eyes looking right.

From the front.

The eyelid strips are longer on one side to act as levers.


Twiddling eyeballs

This is the basic mechanism. It needs hooking up to controllers and needs eyelids attaching. The metal eyelid is the equivalent of the "superior tarsus" of a real eyelid. The skin is likely to be made from leather