Wednesday, 5 April 2017

Mouth mechanism for a ventriloquist dummy head

The most fundamental moving part of a ventriloquist dummy has to be the mouth.
Here's how I made this work on this dummy - it's essentially a mouth hole with a fixed upper lip and a hinged lower lip. There's an operating lever attached to the lower lip

Here it is in action...


Cutting out the mouth opening

The dummy head was originally carved as a solid head from wood with the mouth carved into the solid wood of the face.



To make the dummy head animatable, the removable face of the dummy needed a mechanism to be attached inside it, but before that could be done, the solid mouth needed to be cut out to produce a mouth hole.

This was done crudely with a saw attachment on a multi-tool.


The multi-tool saw gives a pretty accurate cut for the basic mouth hole. I then needed to emlarge the hole to fit the moving lower lip. Because this lip would be hinged, the lower half of the hole needed straight edges to allow free rotation.


I enlarge the hole with a tungsten carbide cutter burr in the die grinder


Until it was gaping nice and vacuously.


Creating the moving lower lip 

There is no jaw movement at the chin for the mouth. The face has a fixed upper lip and the lower lip is separate and hinged.

This was carved by eye from an oak offcut. Here it is being sized after some initial rough carving.


After some more shaping with the grinder and sanders it started to look like this...


Adding the hinge

The lip was quite simply attached using a light hinge I had amongst my various miscellaneous hinges I keep for such an eventuality. This hinge is a flush hinge that is normally used for box making. In this case, it had the advantage that the wider fixing could be attached to the mask back, with the smaller tongue fixing sticking out. These made it perfect it to attach the lip to. 


To fit the lip onto the hinge, a simple groove was cut into the back of it with the very small multi-tool plunge-cutting saw blade.


It could be eased onto the smaller protruding hinge plate, thus...


Here it is seen from the back.


Fine tuning the fit

Once the lip was fitted to the hinge, it needed a little more carving/shaping to get the fit nice round all the edges. This is easier if done with the grinder held in the vice


But, I realised that the first go at carving the shape by hand had misjudged the size of the back of the lip. To make this better, I use my old friend Plasticine. Here's the original lip and a roll of it.


I judged the required shape by shoving a blob of Plasticine into the mouth and shaping it a bit with sculpting tools and fingers...


Then removed the moulding this made and used it as a guide to carve a new lower lip.
To start I just drew round it.


And then cut this out as a block.


 And then shaped it down with the filing sander locked in the vice.


Until I had created a rough wooden version.



After here it is after some more fine sanding...



As before, I sawed out a new hole in the second lip for the hinge plate to be fitted.


As well as the main cut for the hinge plunge saw, I used a drill bit in the Dremel to cut an extra narrower slot for the control lever.



Once fitted, I made some extra increasingly smaller adjustments by drawing out the waste areas that needed cutting out, before shaping them down further.


Here it is fitted to the face mechanism, as seen from the back...



And in homage to Muybridge, here's an animated GIF of it in action using test shots...


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.


Thus...


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