Thread: Another Variation on 2-Axis Eyes

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I've been watching a lot of animatronic eye videos on Youtube and TheEffectsLab.com, and I've come across a design that I really like. YouTube - MY EYEBALL PROCESS PART 9
So, being the crazy propmaker that I am, I'm going to cram this design in a 3-axis Lindberg. Nothing against the Graveyard Skulls design, but it's so much more fulfilling to go the full on DIY route
So far, I've picked out my universal joints, and they're actually Lego pieces: Lego Light Gray Technic Universal Joint NEW - eBay (item 320085853755 end time May-12-09 21:22:45 PDT)

Now I just have to find a good, hollow sphere around an inch to an inch and a quarter in diameter for the eyeball. The trick to doing this effectively is to have a full ball that I can cut down to 3/4 of a sphere, rather than 1/2, so it can swivel around and appear to be whole. In the video, Gary made his own mold out of two brass beads...but those cost him 50 bucks a piece...I need a cheaper option. Any ideas?

Are you really going to cram 4 more servos (2 for each eye) in a Lindberg in addition to the 4 already there?

No, two more servos. See, I only need to control one eye (connected to the other with a rod) in order for both to move. Alternatively, I can put the vertical servo on one eye and the horizontal on the other for the same effect, again with the servos connected by a rod with a pivot at the center of each eye (which I believe is what Bob and Joel's new design does).
Actually, it's not even a true Lindberg. I'm using an original Boris skull, which I am entirely convinced is a recast of a Lindberg, but, when you take out the electronics and additional plastic on the inside, it actually is roomier than a real Lindberg. I'll post a pic when I get a chance.

Originally Posted by Mr_Chicken

I'm using an original Boris skull, which I am entirely convinced is a recast of a Lindberg, but, when you take out the electronics and additional plastic on the inside, it actually is roomier than a real Lindberg. I'll post a pic when I get a chance.

Yes it is a Lindberg recast. I replaced the missing banks of teeth with Lindberg teeth.

This was the same method used last year (check out Pete's Animatronic Eye Mechanism on YouTube). I used the same Traxxas yoke assemblies (the one's in Willetfx's vid) and other u-joint options last year also. I found that this method does allow very fluid movement but it is also hard to control without dedicating two servos per eye. The eye moves without any constraint unless you tie it down. You don't have this problem with roll-on type eyes, the constraint is built around the eye very much like human eyes in their sockets. This makes it easy to work around with only two servos.

That is pretty nifty.

I really wish I knew how to do this sort of thing, as I wanted to make a portrait with moving eyes for my Halloween party this year.

Originally Posted by HomeyDaClown

This was the same method used last year (check out Pete's Animatronic Eye Mechanism on YouTube). I used the same Traxxas yoke assemblies (the one's in Willetfx's vid) and other u-joint options last year also. I found that this method does allow very fluid movement but it is also hard to control without dedicating two servos per eye. The eye moves without any constraint unless you tie it down. You don't have this problem with roll-on type eyes, the contraint is built around the eye very much like human eyes in their sockets. This makes it easy to work around with only two servos.

Yup, what I was gonna say. Even if you get the connective rod between the both eyes loose enough to work, the slack will cause the eyes to move out of sync if that makes sense. Not to say it can;t be done, but animation will be a hassle.

Originally Posted by HomeyDaClown

This was the same method used last year (check out Pete's Animatronic Eye Mechanism on YouTube). I used the same Traxxas yoke assemblies (the one's in Willetfx's vid) and other u-joint options last year also. I found that this method does allow very fluid movement but it is also hard to control without dedicating two servos per eye. The eye moves without any constraint unless you tie it down. You don't have this problem with roll-on type eyes, the constraint is built around the eye very much like human eyes in their sockets. This makes it easy to work around with only two servos.

Ah, yes. Pete's video was one of the first ones I found.
What do you mean by "constraint?"
I don't picture there being much conflict in getting the other eye to follow if they are connected with a rod that only pivots on the horizontal. I may be wrong. I'm going to do a crude mockup this evening, and I'll report my results.

I think it would be cool to do it with four servos, then you could have your skull go cross-eyed or have a lazy wonk eye!