I needed a mandrel to use as a form for shaping the Hellboy egg shell. I found a wood egg at a local craft store for $2. The length is about right but unfortunately the diameter is way off. I also don’t know if the film version had a round or flat bottom since it’s very hard to tell by watching the film. I’m guessing there were a couple of versions of the small egg in the film. The open version that you see standing on its own was able to rotate on the box top in the film (during the sequence when Nuada is assembling it) so I’m thinking the bottom had a flat area where it was attached to the table/rotating mechanism- it looks like it does when you get a very brief side view of it in the film. The egg that Nuada is holding in his hand is first the small version (closed) when he takes it out of his pocket, then switches to the large version during the opening sequence and then switches back to the small version (opened) when he removes the elemental bean- all of these appear to have a round bottom but I can’t be 100% sure due to the angles at which it is seen.
In order to make this wood egg work I coated it with a layer of ApoxieSculpt and then turned it on a lathe. I printed out a line drawing of an egg that appeared to be the correct shape and then used that to cut out a template. While turning the egg shape on the lathe I could then use this template to check the shape of the egg. The turned egg is approximately 3 7/8″ tall and 2 7/8″ diameter.
The egg mandrel has to be slightly smaller than actual size due to the thickness of the brass sheet used- I’m starting off with material around .030″ thick but I can run it through a rolling mill if I need to reduce the thickness slightly. Once I anneal it I’ll hammer form it over the egg mandrel and then trim each panel to the required shape. Believe it or not that’s actually the easy part. The tough part of the fabrication is all of the pivot points required as they really can’t have any slop in them if it is to close correctly. I’m still finalizing all of the mechanics but I think I have the assembly sequence and how all of the parts have to fit together mostly figured out.
With the Stargate helmet finished and the animatronic wings well under way I’ve been thinking about making the Elemental Egg from Hellboy II: The Golden Army. This is a project I’ve wanted to tackle for quite a while and after giving it a fair bit of thought I think I have a good idea as to how to make it.
For the film I believe two eggs were constructed; the first actual size (I’m guessing approximately 4″ long with a 3″ diameter, maybe even a bit smaller?) and a second that was quite large that was used for the sequence where the egg opens up to reveal the elemental bean- I’m guessing that it was either animatronic or cable control.
What I want to make is an actual size egg that opens up- an animatronic egg display piece. I plan to do this by having the egg mounted to a base and having servos open the upper section and the lower section of the egg. The servos will be hidden in a box underneath the egg. The lower section is pretty tricky as there are 24 individual plates that open outward and they open at different rates. I would also like to make the bean glow during the animation sequence. At this point I think I have the majority of the mechanics figured out and I plan to construct the egg shell by forming brass sheet over a mandrel. I imagine one of the hardest things to accomplish will be having the plates close properly- it will require very precise fitting and manufacturing of the mechanics.
This is going to be a tough project!
A couple of screen caps-
After a VERY long absence Episode 4 on the Stargate helmet is finally up. Next episode will be about picking servos for your project. For anyone that needs help with their own project just visit the forum and I’ll try to help out as best as I can!
There is a complete build tutorial on Instructables.
DIY Animatronics Forum
As it turns out I wasn’t quite done. After getting everything together I realized the head needed to move up and back, which meant I had to machine a new neck pivot and then adjust the control rod length. Here’s the new neck pivot assembly.
The really fun part was the caps for the fan mechanisms- once I hollowed them out they didn’t fit- doh! I thought I took really careful measurements but close wasn’t close enough so I had to make new linkage parts so I could get the caps to fit properly. I also had to add the the little brass sliding tabs that cover the open gap as the fans rotate- just like on the original movie helmets.
Now the caps fit properly. They’re held in place with magnets and a round socket that fits over the fan mech pivot retaining collar so they can be easily removed if any repairs should ever need to be done.
Got both of the fan mechanisms installed yesterday- really tricky to get them aligned properly. I also changed the way the head shell mounts to the head mechanism. I’ll shoot a build video this weekend that shows all of the movements and how it all works. After that it’s time for this bird to leave the nest and travel to its new home and get a proper paint job.
I’ve been wanting to make a set of animatronic wings for some time so when I was asked to make these I pretty much jumped at the chance. This is a pretty challenging project for a couple of reasons. First, wings put a pretty big strain on servo motors so you need really powerful /durable servos and you need to make the wings very light weight. Second, there’s no room to mount any hardware! You can’t put the servos, batteries and controller board under the clothes and the mechanics are fairly complex as all four wings need to move up and down and flap forward and back. Everything has to fit behind the costumer’s back. You also need a hidden harness to support the wings. The trick with this project is not only to get everything to work properly but to make it look right. While there’s absolutely no way to make it look exactly like the pictures below I do believe it’s possible to get close enough and maintain the look of the character while still getting those awesome wings to move properly.
Got the fans moving- woohoo! They move just like in the movie with the uppermost fan having the greatest movement and the bottom fan having the least movement. The servos have no trouble moving them, even at 4.8V (the servos are rated @7.4V) so no helper springs will be necessary.
Here’s the nearly completed mechanism that makes the three fans move on each side of the head. Note that the schematic in the previous post shows the left side of the head and this is for the right side of the head. Still have a little bit of relief machining to do and drilling the fan blade mounting holes. After that I can attach the fan blades and power them up!
In several scenes in the movie Stargate you can see how the fans on the sides of the Horus and Anubis helmets rotate in a progressive manner, with the upper fan moving the greatest amount and the lower fan moving the least. It’s a really cool effect and the set of three fans on either side of the helmet was made to move using a single servo. There’s not a lot space in that area of the helmet so it has to be a fairly compact mechanism.
In order to replicate this I created a kinematic model of the mechanism using a free program from Autodesk called ForceEffect. This is a great bit of software that allows you to plot motions of all kinds of linkage mechanisms. I would have killed for software like this back in the day (20+ years ago) when designing suspension mountain bikes as I used to plot kinematics manually on paper. The fact that you can use an app like this on your phone or tablet is just awesome.
Unfortunately the photos I have of the original mechanics are not direct side shots and a fair bit of modification/extrapolation was required to get the proper range of movement, taking into account the necessary leverage ratios and clearances. The original helmet mechanics used helper springs to overcome the high leverage ratios- I have the benefit of modern digital servos that are much more powerful than the analog servos used when the film was made. The downside is that digital servos use more power and are noisy but that’s the price you have to pay…
And I’m back! After the hectic pace of work and home life for the last few months I’m glad to be working on this again. Working on the fan mechanisms right now but the head is mounted and ready to go.