The Videographer

As mentioned elsewhere, a manikin of myself yielding a video camera, (another passion of mine) will lean forward as the minaret doors open, and film the birds as they rise higher into the air. For general information, this image below shows the original mechanism used to open the doors and lean the Mad Hatter forward.

Initial Mad Hatter and door mechanism design

My mechanism is somewhat different, but still uses a single motor to do both jobs. It is largely constructed from old Meccano parts and is shown in a simplified form in the diagram below. The mechanism is shown in its deployed state i.e. with the doors open. A motor drives a toothed cog held by a bearing fixed to the base of the minaret house. Attached to this cog is an arm, on the end of which is a pushrod which links to a hook on the bottom of the back of the left door just beyond the hinge. As the motor turns, the arm rotates forwards thus pushing the back of the door forwards. A microswitch (not shown) is positioned to cut the drive to the motor when the doors are fully open. When the motor is reversed, the arm pulls the door closed. When the door is fully closed, another microswitch operates to turn the motor off.

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The toothed cog has a chain linked around it which is crossed over itself to turn a similar cog and arm on the other side but in the opposite direction. This operates the right-hand door.

The manikin is attached to the front of the base of the house via a hinge, just behind the closed doors. The left door arm also has a long Meccano rod pivoted to its end, the other end heading to the rear of the house and running through a loose slide on a pivot attached to the baseboard. This allows the rod to slide backwards and forwards as the door arm rotates. Halfway along this rod is attached a pushrod, the other end of which is attached to the back of the manikin above its hinge. As the rod moves forwards and backwards, the manikin is thus made to lean forwards and backwards.

My mechanism for opening the doors and tilting manikin forwards.

Rear view of minaret door and manikin mechanism.

This image shows the actual mechanism from behind. The left minaret house side panel has been removed to take this picture. In the upper foreground can be seem the motor and gearbox. The “deployed” microswitch is mounted to the baseboard below the motor and actuated by a linkage to the rotating arm. This picture clearly shows the manikin tilting mechanism. The rear end of this linkage arm is guided in a pivoting slide fixed to the baseboard. The manikin hinge can be seen below the manikin in the centre of the image.

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In the first image below, you can see the microswitch that shuts off the motor when the doors are closed. It is shown bottom right and is situated on the baseboard in the centre of the door opening. When the doors are closed, they actuate the switch.

Front view of left door linkage.

Front view of right door linkage.

In order to make the manikin of myself, I first took various pictures of myself holding my video camera, from back, left, front, right. These are shown side by side in the image below. 

Four photos of myself for the manikin

Finished manikin.

Using blocks of Basswood, as used for the birds, I traced the outline of myself onto the blocks of wood and cut them out on the bandsaw. Further carving and filing and a little application of wood filler completed the model. It was made in seven parts: the camera, head, torso, upper arms, lower arms. All parts were then glued together, the joints filled and smoothed, and finally painted with acrylic paints, then sealed with clear lacquer. It was attached just behind the doors of the minaret house via a hinge, and coupled to the door opening mechanism via a link attached to the back. I had to carve away a good portion of the rear at the bottom to allow the chain linkage to pass underneath when the manikin was retracted. The position of the link was critical as too high and it would not retract enough, and the doors would hit it when closing, or too low and it would move too far in and out.

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The sequence of events is as follows: the controller first opens the doors which causes the manikin of me, the videographer, to lean forward and point the video camera down. Next, the birds start to rise out of the tub and fly around in circles with their bird sounds playing as they rise. Once they reach the top, they continue to circle while the next event starts. For the shutdown stage, the birds continue rotating as they lower down into the tub, when they stop. The manikin then retracts as the doors close.