Category Archives: Halloween

Talking Birds, Part 4

As previously discussed, the first generation talking bird was mechanically larger than the feathers covering it (fur, actually). While I did not have time to improve on the first bird, the second bird will be mechanically more compact.

The trick is in how to mount the ball-and-socket rod ends. While the the ball-and-socket allows for the rod to swivel 360° around the pivot point, it allows only a couple of degrees of movement up and down. That is if you screw it down on a flat surface.

I figured out that by cannibalizing a rod end, I could screw the ball down atop another ball. This gives a lot greater freedom of movement. By doing this I’m able to place the rod at a steeper angle; thus, the servo can be placed closer. See the rod end mounted to another ball:

Improvement on neck joint

Fascinating, you say? If you had spent 4 hours of your life staring at the end of a threaded rod, you too would find it fascinating.

I know I’m not improving my position, so let’s move on.

Having made my minor improvements to Rev. 2, we now have two functioning mechanisms:

Identical, plus improvements

Note that I also tightened up on the chain. This is an easy thing to do when working with plastic chain. Twist it sideways and the links pop off, allowing you to shorten or lengthen at will. Assuming the chain is perfectly straight in the sprocket, the chain should take quite a bit of tension before it breaks.

How much tension? I have no idea. Doesn’t matter because I have no idea how much torque is required to lift two puppet wings. Let’s hope not much.

Talking Birds, Part 3

There has been quite a bit of head scratching over the last two weeks. Somehow the design I scratched on a Post-It Note wasn’t exactly to scale. I was close, though. Damn close. I’ll continue to use the Post-It Note method.

The plan was to mount the servos along the backbone such that there could be levers that push the mouth, neck, and wings. Moving the mouth turned out easier than I thought. There was enough space in the head of the puppet place a servo:

Mouth servo

The neck and wings still presented a problem. The neck levers had to pass over the wings servo and shaft. In order to make the geometry work out, the servos had to be moved to the very rear of the puppet:

Neck servo and wings servo

Actually, they end up hanging out the ass of the bird:

Measure twice. Cut once.

Unpleasant, I know.

At this point I am in total disbelief that I got it this far. I hooked this thing up to my new Northlight Systems servo controller and the thing actually works! Sure, this is a simple machine and I pretty much knew that the pieces could move by pushing them with my fingers. Still, there is always that chance that the thing could somehow go nuts and destroy itself.

I’m easily entertained by mechanical systems. The is an obvious byproduct of working in the software industry. I have issues with having spent my entire career never having made a product that does something. Maybe I wouldn’t think about it so much if I were an accountant or policeman. As an engineer I’m very much jealous of people who get to make things like cars or bombs. Maybe not bombs. Let’s consider it an extreme exemplar.

Anyway, now that we have one working, all we need to do is copy it…

Talking Birds, Part 2

Truth be told, I like planning these projects much more than assembling them. I learned several years ago that manufacturing things is hard. In fact, the smaller the parts the harder it is.

Conceptually, the parts of the bird go together like Lincoln Logs. Objectively, it’s really hard to make anything out of Lincoln Logs that you can fit up the butt of a hand puppet.

It would be great if only my local hardware store would stock a myriad of little brackets in varying sizes; tiny little metal shapes that would have no use in home construction. But they don’t.

I know. Some hobby stores carry some Erector Set like things for mounting servos or other small items, but they often get $4 for a ¼” L-bracket and that just doesn’t seem reasonable. Even at 50¢, you have to ask the question “How long will it take me to make these with a hack saw and a length of L-bar or U-channel?” If you cut the parts yourself, you can have any size you want for very little money.

Here’s an example:

Neck joint

How to create a neck joint at the top of the backbone? It needs to be at a certain angle and have a certain range of movement. I’m not sure how it should be done either. I think that a rod end affixed to the end of the L-bar should work.

And yes, I’m totally guessing at the angle.