“Grim” 2023

One of our oldest props is “Grim”, a pneumatic pop-up that sits center-front in the display. Kids love him. Dogs hate him.

We first built him back in 2006, and every few years his face – up until now usually a latex mask over a foam skull – rots and falls apart. We saw signs of latex fatigue last year. This year we took him completely apart and updated him.

(See Grim 2006, 2007, 2019)

So the list of changes looks like this:

1. New Skull
2. Some articulation in the jaw
3. Sculpt a new face onto the skull – no more mask!
4. Give him a new cloak
5. New eye-lighting
6. Fix the mechanism
7. “Maybe” some sound effects?
8. Putting it all together…

1. New Skull

The skull came from an old ground-breaker kit.

2. Jaw Articulation

This was going to take some surgery. Mike made an aluminum frame to hold the new jaw, and act as a hardpoint for mounting the skull to the neck (always a weak point in the old prop!). Later, we would add a tiny spring at the back of the jaw to allow the jaw to open and close at the top and bottom of a jump.

3. New Sculpt

Using Polygem EZ Karve and a reference picture, Rebecca went to work on the facelift.

5. New Cloak

4. New Eyes

The ping-pong balls weren’t doing it for us. We decided to use the same 4-color RGB eye-color device as we used in Lasher

6. Fixing the mechanism

Tighten up the arm frames — honestly, I think I’d do it very differently today. Maybe I’ll build another prop next year… something a little more advanced.

New bungee cords were needed. The old ones had lost their stretch, resulting in uneven torque on the extended frame. This would cause Grim to ‘rotate’ when fully extended. I noticed the pvc tube that held the centering rod was pivoting as well, so I made some new wood blocks to hold things in place better.

I put new air tubing on the solenoid – after 20 years, the old ones had picked up some — residue inside. *bleh*

Then the base got a new paint job.

7. Maybe some sound?

As of this posting, not yet. This would be a piece of cake if Grim ran on 12 volts like the newer props. But he runs on household current. The motion sensor came off of a security light fixture. When it triggers, it sends household current to the actuator — which would blow the poor arduino’s mind. So, until I swap out the motion sensor, or get a household-current relay, he shall remain silent.

8. Putting it all together…