Saturday, September 25, 2010

AUTOMATA - "DiggerBot" Pt.5

Well, there's not much to show this week, except a messy workbench. But I do have some sketches of "problem solving". There were design issues that I had not yet figured out, so I needed to do some thinking on paper before I spent more efforts in wood.

One of the things I decided to add to the movements was the DiggerBot's mouth opening and closing. I had considered using a string or wire, which would pull on a hinge...but ended up with a simpler idea. The weight of the head will press down to keep the mouth closed. But a dowel in the neck will be pushed upwards by a lever, and gravity will pull the jaw open, as the head goes up.

I had cut out a more organic shape for the larger support arm. Originally the flat side was on the left, like an "L" (see sketch above). But I looked at modern diggers, and flipping the "L" was more like today's style. I had also made a circular end-piece for the lower arm. I now prefer the way I did the upper arm, so I'll have to modify them.

Once I had flipped the "L" shape, I was wondering about some other embellishments. On a modern digger, there are hydraulic arms that push and pull the main arm. Mine will be just for looks, since the support arm will be glued stationary.

Next, I just started sketching some variations on proportions and design. As I was working on some of the bits and pieces, my original prototype model started malfunctioning a bit. The earlier "belt drive" began to slip some, and the cranking motion wasn't working consistently. So I got a little concerned that my final version would have "issues". So I began to consider a gear driven mechanism. It seemed like it would be sturdier, and more dependable. I also spent a little time figuring out the cam-driven lever that would make the head go up and down.

It didn't take long before I was again handicapped by my lack of engineering skills. So I started sketching around with how I'm gonna make these wooden gears. Luckily, has some demos from woodworkers to give me some help.

So this last page has the basic gear-drive in place. I also thought that I should flip the triangular "tank tracks" around, more like early World War I versions. This approach would let me hide a second gear underneath, which would now become the axle used for the crank handle. The early model had a gear-box underneath...this way I can let the DiggerBot rest on a single base of wood.
That's it for this time...hopefully I'll make some progress on the construction next week. (I have to be honest here...this is moving slower than I want, and is not as much "fun" at this stage. I know I'll enjoy painting this guy...but that's a long way off. )


linsolomons said...

It's great all the research you put into this will be awesome!

Warren said...

Thanks, Lin...that's just the encouragement I needed to avoid being a "quitter" on this thing. I think I bit off more than I can chew, but I'm gonna finish it. May be the reason I haven't built a wooden toy for a couple of years!! I'm too impatient.