noodleFeet : Goes Metal

I’ve relied on 3D printing for so many of my prototypes lately, and have finally come to a point where plastic won’t cut it any longer. I require metal, in this case aluminum. The likes of which I ordered from McMaster-Carr and received in the mail last week. I literally spent the majority of the weekend meditating over how to measure my cuts and holes… as for the first time in a long time, their accuracy and placement was entirely up to me and my calipers, not some Cartesian goo plotter as I’m so spoiled by…

While everyone was downing beer and watching the Stuperbowl, I was in the garage with Mark playing with his father’s ancient drill press. He eyeballed one axis, I checked it against the other, and we were able to punch the 24 holes needed on the four pieces of aluminum tubing which would soon be noodleFeet’s strong new legs.

IMG_1445

As you can see, I printed out little strips of paper with lines where holes needed to be drilled. It only occurred to us immediately after we finished how much easier this would have been if we had 3D printed a jig for drilling the holes instead… So alas, 3D printing could have potentially saved the day. Thoughtful or not… we did a pretty good job.

Once the aluminum femur was assembled, I realized I was going to need stronger springs. These flour legs are going to support eight motors, a board, and eyeballs; a decent amount of weight:

IMG_1448

The calf bit is essentially a bone buried within the noodle material. However, with my last prototype, the bone kept sliding out the clearance slot I cut in the noodle. So to remedy this I made these little braces that look like pac-man heads… which keep the bone centered within the tube and prevent it from popping out where it isn’t suppose to:

IMG_1456

The rare and beautiful white noodle was harvested by Mark from the great noodle beast itself. I cut the pieces to length with a Japanese saw and carved the appropriate clearance slots so that the legs can fold in on themselves like they should:

IMG_1460

The new servo and leg bracket is THICK. It is complete with roller bearings spaced a decent amount apart vertically to keep the intersecting pipe from wobbling around (as with my first prototype):

IMG_1454

The eight roller bearings hold the pipes perfectly parallel to one another and allow them to turn nice and smoothly. I also added stronger springs to tension the legs outward, so the new prototype is a little monster. Although… he looks sort of helpless up-side-down on my bench right now:

IMG_1463

At this point, Feet is nothing but a pile of feet. He needs eyes, and that is exactly what I’m going to do next… and maybe a brain. Over this weekend I’ll likely hook an Arduino up to his servos and figure out a walking pattern too.

I honestly have no idea what it’ll look like when he walks, but I’m hoping due to the springs counterbalancing his weight that he’ll have a little bit of a bounce. That’d be cute.

I also don’t know if he’ll be able to balance himself when he walks. Once summer happens and the noodle is less rare, I will go harvest some 4″ stock (in neon yellow) from Walmart and cut my prototype some new fat feet. That way he makes more contact with the ground and is less like to fall. Like training feet.

IMG_1475

Hopefully by my next update he’ll be moving some… like a robot aught to. Cheers!

mechaFeet : Prototyping with Algodoo

I had to wait this week for the sensors I ordered to come in the mail before I continued progress on Jelly. With Jelly on hold, I couldn’t save myself from starting on yet another project idea I’ve had fermenting in my mind for a while now. It involves building a pair of mechanical chicken (or raptor) legs that can stride in sync with one another; both legs driven by the same moving part. The thing that initially inspired me to make a mechaChicken was this quirky and utterly gorgeous mechanical hand ostrich thing by Tim Lewis called “Pony” (that and all the stupid bipedal robotic dinosaurs that are in the stores for Christmas this season).

My problem is that I don’t have a whole lot of experience with big kid mechanical motion, so it took a lot of meditating on before I even got started.

Two nights ago, I laid in bed and mused over parallelograms. When I woke up, my mind was running an animation loop that I must have seen somewhere at some point in my life. In any case I understood what sort of shape I needed to build to get the movement I wanted. So, I rushed to the closest scrap of paper and drew it before the idea escaped:

mechafeet4

After I made the doodle I played geometry Sudoku with the lengths of the pieces. Once I was satisfied with my own logic, I designed the segments in CAD and printed the eight individual bits to test. I eagerly screwed them together to find that the ‘mechanical leg’ moved EXACTLY like I thought it should… the proportions needed to be tweaked a bit, but it worked:

mechafeet3

This wasn’t good enough in itself though. Now I had to figure out how to drive the leg in order to execute the motion correctly (which isn’t as easy as you’d think). After spiral-graphing the top of the ‘thigh’ in motion by manipulating the ‘foot’ of the piece, I saw that the thigh tendons were arching in circles, so I knew I needed to create a wheel of some sort… which I did, but it sucked:

mechafeet1

Sucky wheel sucked because I didn’t take into account that the tendon piece of the leg would need to clear past the center of the hub, flush with the wheel itself. Of course, I had a screw mounting the wheel in place, so the head of that said screw got in the way… ruining my night. Easily remedied… but… Bleeeeeeeh very fussing. so much tedious.

Around now, Mark suggested that there ought to be some sort of 2D motion simulation software out there in the ether that I could use to test my ideas. I was starting to wonder that too… as I was minutes away from hopping on Little Big Planet to make use of their physics tools, tehe.

Last night, after some hunting, I found Algodoo. What a wonderful discovery… It allows you to draw out (literally) your arms, connect the joints with screws and drive them with motors, just like life but without the toil of actually building the prototype. What do I mean? I made this in about 5 minutes and it gave me the exact same feedback:

mechafeet2

In my video I give a brief introduction to the software while explaining how to make my chicken leg. As of right now, I still haven’t figured out what kind of motion will properly drive it, but I’m well on my way to getting there (without wasting PLA!)