Monday, October 13, 2008

Follow up to Monday's Model

Over the weekend while I was writing today's post, I had a few questions (and apparently a few mistakes as well). I sent some questions about how many motors, programmable bricks, etc were used along to the builder (who submitted it himself), and here is the response:

There is only one LEGO Mindstorms NXT servo motor for the mouth movement.

The lighted eye is controlled by a LEGO Mindstorms NXT Light Sensor.

Originally, I was going to cram a "power Functions Light brick" from LEGO set 4998 and another LEGO Mindstorms NXT servo motor to control the Light brick, but as I began learning more about LEGO Mindstorms NXT (and modern LEGO pieces), I realized that the LEGO Mindstorms NXT Light Sensor had its own light source!

As for brick techniques, one fun one is that the transparent inner eyeball is made up of these 4 pieces (via

1. a clear Minifig Accessory Helmet Modern (2446)
2. a TrOrange Minifig Head with Hollow Stud (3626b)
3. a TrRed Plate 1 x 1 Round (4073)
4. a TrOrange Brick 1 x 1 with Headlight (4070)

The skull itself can be controlled by only 1 programmable brick which coordinates the control of the light sensor for the eye, the servo motor for the mouth movement, and to playback the uploaded sound files.

The cheap lazy susan I found to spin the head is controlled by another programmable brick that controls either 1 or 2 LEGO Mindstorms NXT servo motors.

For this talking skull, only one servo motor is sufficient to spin the head, I have 2 LEGO Mindstorms NXT servo motors in the videos so that it looks symmetric.

In case anyone tries to make the spinning platter just by viewing my videos may run into some problems - to keep the tires of the motors on the rim of the platter, unseen LEGO Technic spring shock-absorbers provide upward force to the backend of the motors which are mounted in a simple inverted first class lever design.

I guess that only 2 Mindstorms sets were necessary (I actually opened up 6).

I don't know how many pieces I used and I'm not sure where each piece came from, though I probably can trace the odd ones back to their respective sets.

I built the skull first, then went on a few LEGO shopping sprees for newer pieces in colors I wanted, additionally, I broke down my ancient LEGO Expert Builder sets, and integrated some second-hand LEGO pieces Mom purchased years ago.

Everything is genuine LEGO, absolutely no glue was used, no piece was forced into a compromising position, and no Technic Pins with Friction were used (I don't like the way they potentially widen the holes of technic beams).

The skull is completely modular, everything quickly comes apart in multiple modules by pulling bushes and cross axles.

Thanks to w at for clearing those things up on such short notice (this was sent in a few weeks ago and I only had a chance to look at it this past weekend).

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