The weekend has been spent trying to make Pete some eyes. I've never made animatronic eyes but have studied how makers often achieve them using servos and so I thought that would be my approach. This blog details my attempts to make some servo eyes.

 

Idea ONE - table tennis balls. They would be lightweight and could be illuminated. But they were also too small. I also realised at this point that they eye holes were not the same shape or size (and why would they be as Pete was made totally freehand).

 

Idea TWO - borrow the silicone poached-egg moulds. They could be squashed to make an elongated eye to fit the openings. But I would want to use something non-toxic and so decided to use salt-dough. I squashed them appropriately and fixed to a cheese board, covered in a mix of flour, water and salt and layered up some kitchen paper into the layers I applied to the outside of the mould. I then cooked then for about 2 hours at 50 degrees centigrade. Whilst they were hardening off I made a framework (Framework Mk1) with wood and aluminium to make the two eyes move together. It was difficult to determine what sizes to use for just about every single measurement - nothing inside the pumpkin head was symmetrical. I also realised that the eyes would look better if not on the same horizontal plane but instead canted inward - the intended mechanism would likely no longer work like that. The 'bread' eyes were not a great success. They were not very strong and had an uneven surface. I was also wondering if they absorbed moisture then they would fall apart. The framework includes a nylon washer between two steel washers and makes quite a good low-friction joint.

{gallery} Salt_Dough
Silicone Egg Moulds
Salt Dough Eyes
Framework Mk1
Low Friction Pivot
Eyes Cooling Off

 

Idea THREE - Oasis florists foam. This lightweight foamed block is used by florists for flower arranging. I carved up an old block to make some eyes. I gave them a finishing sand over the bin and sealed them with PVA glue. The next day they were still wet and I wondered how I would attach them to the framework. The Oasis is very fragile and would likely be easily pulled apart or damaged.

Florists Foam Used for Eyes

 

Idea FOUR - car body filler. After agreeing I could write-off the egg moulds I decided to try car body filler. This is the very toxic 2 part stuff which sets in about ten minutes and makes a great glue/filler. I made some aluminium cross pieces complete with a small turned rod middle that I could attach to the frame. The eyes came out of the moulds well and there were a few gaps which I thought would make a great effect if they were backlit. I then realised that although I had counterbored the small piece of aluminium rod I had not done the same to the aluminium angle that I had glued it to afterwards. Therefore I could not pass a bolt through as intended. The solution would be to make a small hole inline, open that out and then to drill through the aluminium.....but even with careful support, as the drill broke through it caught and snapped the fragile eye. The same happened to the second one

{gallery} Car Body Filler
Car Body Filler Eyes with Aluminium Support
Broken Bits of Eyes

 

Idea FIVE - back to paper mache. I stuck the egg moulds into damp sand to keep their respective shapes and lined each with newspaper/PVA glue. They are currently drying and will be my new hope for the next few days.

Paper Mache Eyes

Framework Mk2

I also decided to make the framework again but this time to go for two separate servos allowing them to be mounted as required to get distances and angles correct. Below is a picture of the pair of servos I've made. The brass connector to the servo horn is from a plastic screw terminal block. It couples the old bicycle spoke to a piece of solid copper wire. This allows adjustments while the copper is thinner than the spoke also.

Framework Mk2

 

Lighting

Assuming I actually get these eyes to work, my new PIR sensor arrives and works and the stepper motor can move the whole arrangement, then it would be cool to have some lights. I soldered up two pairs of WS2812 RGB LEDs (one pair for each eye).

{gallery} WS2812 Lighting
Unsoldered WS2812 units
Part of the WS2812 lighting  jig

Next steps:

  • see how the eyes come out tomorrow
  • add the cross mounting bars inside them
  • paint the eyes
  • work out how to fix them in place inside Pete's head
  • continue to write the Arduino code
  • get the PIR sensor working

 

 

Rod