Building a Better Shoulder

Much like the knee design a while back, I wanted to improve on many of the standard designs for shoulder joints seen in action figures on the shelves.  To start, I decided I wanted to incorporate a rolling shoulder design in addition to the normal shoulder joint that you see on every figure.  This isn’t that unusual, and if you haven’t seen it, a rolling shoulder makes a world of difference to the realistic pose-ability of your figure.  Without it, you end up with very stiff ‘action-figurey’ poses instead of the more human poses seen in higher-end figures.


There are already plenty of good examples of rolling shoulder designs on the market.  Many of them use a ball joint deep in the chest which the outer joint is attached to.  This is fine for smaller 1/12 scale figures, but I was concerned about a ball joint reliably holding a pose on a figure this size.  I also wanted to avoid the ball joint since it would allow the shoulder to move on 3 axis, and I wanted to limit it to 2 (being able to move forward-backward and up-down without rotating).  To solve this, I put two single-axis joints together inside the chest cavity.  This gives the joint all the movement I wanted it to have.  I also put a ratcheting ring in each of the joints to help hold poses.


The shoulder blade went through several different iterations before I had something I thought would work.  At first I thought of putting in sliding joints on ball joints, all this complicated stuff that would be really unreliable, prone to breaking and would most likely get stuck too frequently to work.  Instead, I put the whole scapula on a small rotating piece on the back.  The scapula is attached with ball joints on the shoulder and rotating piece to give it freedom of movement.


While this prototype isn’t perfect, it turned out far better than I expected for a first attempt.  Everything works as intended, and it actually looks really cool when it moves.  Something about adding that shoulder blade in gives the movement a very natural, organic feel.  There are still changes to be made before moving onto the final version, but this will do for now.  This piece was probably the most experimental part of the figure, and the one I was most concerned about getting to work.  But holding a working version in my had is deeply satisfying.  I’m feeling a little more confident about everything else.


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.


Designing the Helmet


The initial concept

One of the biggest features I wanted to include with this figure was a helmet that can open and close.  I want to show her face beneath the helmet without having to make a second, swappable head the way most manufacturers do it now.  Also, having complex moving parts may make the build more complicated, but I think the end product is far more impressive than simpler figures.

I started this process with a basic idea of how it would function.  Maybe a hinge at the top of the helmet.  Then I added in a parallel set of arms in the helmet to make the movement more interesting and mechanical.  I started playing with the length and angle of the arms to see what effect that had on the angle of the open helmet, and even mocked up some quick ideas with Lego pieces I had available.  Once I had something I thought could work, I quickly laid it out in Maya and went to the 3D printer for prototyping…IMG_3068

…and my first attempt was a mess.  Parts printed poorly, critical pieces were designed too small, some of them broke immediately on use.  I was a little disappointed, but I learned a lot.  Just because something looks like it will work on the computer doesn’t mean it will translate well to a physical model.  So I went back and adjusted.



Success from failure

My second one came out far better.  It actually worked!  Pieces fell off here and there, but it was successful as a proof of concept.  However, after that initial excitement wore off, I tried to look at it more critically to see if there were any more improvements necessary.  I realized that while it did work, it wasn’t actually opening as far as I needed it to.  This design wouldn’t even get the helmet above her eyeline.


Tweaking for better results

Since I knew all the basic components worked, I went back to Maya and made a few different designs there.  I tried changing up the arms to see what would give me the most clearance, and once I had something that looked better, I printed out the new pieces.


Working prototype

The resulting helmet is even better.  These pieces will make up the internals, and I can build the body of the helmet around it.  I’m hoping to have the head completely modeled by the end of April.


Building the Foundation

2This week I started working on the basic pieces for the model.  Right now I’m working on building the core joints that will be used throughout the figure.  I just finished the basic hinge joints that will be used in the hips and shoulders, and possibly main body.  I will be using some variation on them for the ankles and wrists, too.  I took a lot of inspiration from Gundam kits, as well as the joints used in the Kaiyodo Revoltech line.  Much like those examples, I’d like to avoid using too much hardware for this project, like screws or fasteners, so I’m trying to build as much of it as possible to be snap-together like a model kit.


The joints work pretty well in this regard.  I made a test print for the basic joint, and right out of the printer, they snapped together and worked well (aside from the fact that one end of the joint snapped off immediately, but that was from the low fill density I used for this print).  I built in a ratcheting function so they can hold their position better, which also seemed to work nicely.  For the final model I will probably need to do a little cleanup, but as a proof of concept, I’m quite pleased.

1By the end of the month, I’m aiming to have all the joints and a basic skeleton modeled. Moving into April I’d like to start prototyping of physical model of the skeleton to make sure all the joints move as intended.  Last thing I want is to finish it and realize something doesn’t move as intended.