Rethinking Designs

Arm2This week I’ve been thinking about how to get the arm blades to extend in a way I’m satisfied with.  The original concept worked, but after looking at it again, I want a design that keeps the blade a little closer to the arm when retracted.  There were a few basic concepts for the opening mechanism I was considering, and I eventually went with the one I felt was the best combination of practical and aesthetically pleasing.

Designing the mechanism was a bit of a challenge as you want something that can move enough to make a noticeable difference, but compact enough that you can conceal it in the forearm of the figure, which doesn’t leave you a lot of working room.  I’d like to incorporate a simple lock feature into it somewhere so the blade is moving around loosely, along with a trigger piece so you’re not directly sliding the blade in and out.  I feel like designs like this are at least 20% cooler if your hand doesn’t get in the way of the piece being moved.

This concept acted as a chance to redesign the arm itself.  The arms in the original concept worked, but when I look back at it now, I think maybe they didn’t get the amount of detail they could’ve had.  That’s just the nature of concept work, I guess.  You want to design as much as you can upfront, but you can’t get hung up on making every little piece perfect or you never move forward with the project itself.  So, I gave myself some leeway to redesign things along the way as necessary.  Further redesigns will be coming later, but for now I’ve got work to do on these arms.


Building a Better Knee

Knee_Detail_FinalThis week I’ve been working on the design for the knee, and I’ve finally got a working design.  As I said in the last post, most figures I’ve seen have knee joints that could be improved upon, at that’s what I intended to with this figure.  Often they will have an oversized mid-joint area that looks awkward when fully bent.  Double joints also has have a tendency to bend fully at one joint before bending at the other, which is a relatively minor issue, but it’s something that I feel could be improved.  And improve it I shall.

I started with this basic concept of putting geared-teeth inside the mid-joint, and in theory it should make both joints bend consistently and at the same angles every time.  Before going forward, I thought it might be more effective to change the angle of the individual joints.  Looking at the way an actual knee bends, it seems like the kneecap stays with the bottom half of the leg, bending a lot more at the top of the knee.  To simulate this, I made the bottom joint larger than the top, making the lower joint turn more slowly than the top.

It took a few tries to get the gears to work right.  My first attempt used relatively small triangular teeth, and while they looked like they should work on the computer, I once again learned that doesn’t always translate to a physical product.  These teeth didn’t mesh at all and would grind a little bit, but that was it.  They felt more like ridges used for grip than gears.


For a second attempt, I tried to adjust the size of the teeth and make them big enough to work in the physical world.  Once again, Looked great digitally.  Physically…


Still just as ineffective.  They occasionally would mesh a bit, but not consistently, and therefor were still useless to me.  I reevaluated the design some, and realized the main issue was I was designing these gears with pointed, triangular teeth, and the printer was not able to handle sharp angles like this at such a small scale.  They came out rounded and prone to slipping and grinding.  I needed a design that wouldn’t do that.  So instead of the sly and shifty triangle, I moved on to the noble, sturdy square.


And BAM!  Working small-scale gears.  Fewer teeth with larger gaps, and every tooth is securely fitted into its complementary gap with no room to slip.  As long as the housing holds everything in place, they should work consistently, every time.  I printed some quick leg parts to better illustrate the full working leg.  This design works just the way I planned.  These are the bones for the final product, now I just need to add the meat.  Extra Knee_Exploded_Finalfeatures will surely make their way in before then, most likely a ratcheting mechanism somewhere to help them hold any pose.  I would like a somewhat complex knee pad with some movement as well.  But all things in time.  That’s for another day.


Fancy Footwork

The main body has been blocked in, so I’m now working my way back up with some additional detail.  Starting at the feet, I made my way up the knees with some more concrete design work.  I’ve also been fleshing out a lot of the specifics of construction.


The feet have taken some work.  I had a general idea of what they were supposed to look like, but they were admittedly not my biggest focus when creating the concept.  I’m probably going to be doing a few follow-up concept pieces throughout the build to get a better sense of the details.  For right now, though, I like the idea of bringing in some elements of trail shoes to this robotic foot design.  It also made me start thinking about different materials I could use when casting the final pieces.  I want to look at what’s available, but doing the soles of the feet and other parts out of a flexible rubber would really give the final piece some extra flair.


I’m trying something new with the knee design to solve a problem that most likely no one else is really  bothered by.  I’ve always found it a bit awkward how so many figures on the market use a traditional double-knee joint.  Many Play Arts Kai figures, for example, use a ridiculously over-sized joint, which makes for weird poses when bending the knee.


I’ve also had the experience that when you bend the leg, usually one joint will bend all the way before the other starts bending.  So, in an attempt to fix that noise, I’m adding geared teeth onto the joints to ensure the leg bends evenly every time.  It’s most likely over-engineering for such a minor issue, but this is my project, dammit, and it will be meet my expectations.

Knee_Detail.jpgI had gone through a few different versions of implementing this idea.  The last had exposed teeth on the joint, and although it was simpler, I hated the idea of being able to see the inner workings of a detail that should be invisible.  Currently, it’s fairly similar to many of the double joints other figures use, just hollowed out to make room for the teeth on the inside.  I will most likely be prototyping this piece next.  I plan on trying a few different gear ratios.  Right now it’s set up for two gears of the same size, but I think one large and one small gear may actually give a more realistic result.  Looking at the way a knee bends, the kneecap appears to stay in line much more with the shin than the thigh.  To achieve this effect, I think I’ll need a small gear for the top joint and a larger one for the bottom.  More to come as this develops.