Introduction: Zolterno: an Animatronic, Fire Based Fortune Teller

Nearly everyone who has lived for any period of time understands the pop culture references from the Tom Hanks classic: Big. In order to avoid bullying, a young child finds a mystical fortune teller ("Zoltar"), and wishes to grow up. Much to his surprise, his wish comes true. I wanted to recreate Zoltar in a way only Sheet Metal Alchemist could be proud of - made out of metal, and spewing fire :-). This instructable covers the creation of the stainless steel skeleton plumbed for fire effects. Other instructables cover the electronics programming, and the creation of the "streamline" style enclosure from the 1920s.

Zolterno was made as part of my residency at Instructables. So. Much. Fun. He's already been to Maker Faire Bay Area 2013, and will be hanging out for the next couple of years mostly on Pier 9 on the Embarcadero, so if you're in the Bay Area, swing by and say hello!

Step 1: Designing for Fire Effects

Zolterno's entire body can be engulfed in flames. However, Zolterno also needs the ability to flex and move to be a realistic fortune teller. Traditionally, using propane rated flexible hoses was the only way to carry propane through a movable propane structure. This would not work for my application, as all LP rated hoses are made out of rubber or other elastomers which would burn or degrade in the presence of fire. 

A key component to designing Zolterno was the creation of a flexible propane carrying system which would not degrade in contact with fire. Check out the images for a description for an overview of the basic joint, and how they assemble to make mobile, propane-leaking, fire-proof connections!

The basic joint is a set of loose fitting spheres made from half-spheres which are held together by a nifty system of washers and welds (more to be described on later slides)

Step 2: Assembling the Propane Joint...step 1

We'll continue to use the CAD model as reference to these propane joints to try and keep track of what is going on. The big challenge in assembly for these joints is making sure everything will fit tightly where it is supposed to be tight, and loosely where it is supposed to be loose. This problem is easily solved by using the proper assembly order.

For the first bit, we need to do the fillet weld which attaches the washers to the straight bits of pre-cut stainless steel rod. When you start, this weld will be a textbook fillet weld with a TIG welder on stainless steel. No problem! Check out the attached image for my result. I was clamping everything to a stronghand table to keep my angles accurate.

What's TIG welding you ask?! Why...only my very most favoritist kind of welding EVER! Learn a bit about here if you haven't heard of the technique:

Step 3: Add Stainless Hemispheres and "trap" Using Washers

Next, we are going to slide 2 stainless steel hemispheres over the assembly in a back to back configuration. We'll add a washer on top to trap the two stainless hemispheres on the rod, giving the joint stability. 

Where did the hemispheres come from? Right here! Note, they don't come with the perfectly sized hole cut in them, so we mounted them up on a drill press to make the correct sized holes. This was an incredible chore - drilling spheres is near impossible. Perhaps there is a better way to do this on the lathe?

Also, welding the top washer is pretty tricky - the ID of the washers were narrower than the ID of the tube. Instead of using filler, I heated the washer with the TIG torch until the stainless slumps and fuses to the underlying tube. 

Step 4: Fix One Washer to a Hemisphere Wall

This step doesn't do much to help out your design in terms of strength, but omitting this step will make assembly of the overall piece nearly impossible (since every single joint you add will add a ton of floppiness to the overall structure). 

On only one side of the assembly, fuse a washer to the wall of a hemisphere. I could do this really simply by using a gap in my welding table. If you fuse both sides, the joints won't slip, and your piece won't move, so take it easy there Tex.

You'll want to get several units to this step before continuing (how ever many you'd like in your spine). So, repeat steps 2-4 until you can't take it anymore :-).

Step 5: Seal an Individual Unit

Now that we have several pieces ready to be connected, it is time to do the full radial weld on the outside of the stainless steel hemispheres!

The hemispheres I purchased came with a pre-beveled edge on the exterior to ensure a strong TIG weld. Thanks guys! Note that in the attached image, I'm only showing a single spot weld, but you do want to fuse the entire open edge. This weld really does need to be airtight. If it is not, you will leak too much propane out of your system too early, and you'll have a very inconsistent flame when you get to the head and neck pieces.

Step 6: Repeat Until You Get Your Spine!

Repeating steps 2-5 will eventually get you to a structure that looks just like this. It will become the spine for the fortune teller. Note the smooth curve that is simple to make with this configuration.

We'll use this general geometry in other places as well to make the shoulder joints and the elbow joints.

Step 7: Add a Set of Shoulders, and the Connection to the Neck

Use the same basic principles to make shoulder and elbow joints. The main difference on these joints is the location of the holes for the shafts. They will not necessarily be perpendicular to each other.

Additionally, here's a bit of fluid dynamics advice to make sure your entire skeleton is capable of catching on fire. Propane is a flowing fluid just like water. If you take a 1" pipe filled with water and split it into 2x 1" pipes filled with water, each pipe will hold half of what the original pipe had in it (this is the law of conservation of mass...I used to be a chemical engineer before I was an installation artist after all...).

Therefore, as you add branches to your system, you need to reduce the pipe diameter to allow the propane to split evenly through your system. Since I wanted the skeleton to have the appearance of having all the same diameter tubing, I welded smaller stainless steel pipes to the inside of my main body pipes. See the attached images for details.

At the end of this, you should have a set of spheres and rods that resembles a collarbone, upper arms, and forearms. You know. In case you are confused, just reference XKCD.

Step 8: Now We Have a Skeleton, But We Need Clothing...

...stainless steel clothing! (for reals...)

Now that all the propane backbone components had been assembled, I could get to the more artistic bits of designing a proper set of clothing for Zolterno. I sat down with a pen and napkin to do a bunch of theoretical sketches before I moved into illustrator to draw vector paths for all of them. Note that I used a reference model in my illustrator sketch to ensure I properly lined up proportions, body size, etc.

Additionally, I came up with a design for the booth he would sit in as well, and added that to my illustrator sketch. This was to make sure that in the end of the day, my fortune teller wasn't going to be bigger than his house.

Step 9: Waterjet the Clothing

One of my favorite materials and finishes in the world is stainless steel with a super #8 finish. (Yes, super 8 refers to things other than 80s video camcorders). I decided to make his clothing out of this material. #8 stainless is a complicated and difficult material to work with. Due to the perfect surface finish, heat marks from welding show up even worse than normal. Additionally, fixing scratches, dings, or dents is nearly impossible since the mirror like shine is usually the result of an electropolishing operation in industry. 

Therefore, the patterns for his clothing were cut on a waterjet cutter. Plasma or laser cutting would have left heat marks around the periphery of the piece...something I really wanted to avoid. Following waterjet cutting, the pieces were bent on a slip roller or by hand, and then put into place on the model. 

Clothing was attached to the skeleton permanently by using tiny pieces of pin rod and fusion welds.

Step 10: Add Definition to Clothing

Although in theory having a structure made out of exclusively mirror finish stainless may sound like a good thing, there is a stealthy issue that pops up. If you cover a piece in a mirror, you've essentially added active camouflage to a piece - when you look at it, it nearly blends in with its surroundings. This means that the viewer will have a hard time making out individual shapes and contours when observing your piece.

To remedy this issue, I hand brushed some of the stainless back to a #4 finish, but used vinyl masks to keep certain areas at a #8 shine. This not only added definition to the clothing, but made piece details simpler to make out.

Step 11: Make Some Stainless Steel Hands, Part 1

Although making the hands is similar to making the clothing, the attention to detail, and level of pattern precision is much higher, so I've decided to go into a bit more detail about a simpler way to do this.

The biggest hint I can give you about making hand looking objects out of steel is to not try and perfect them right off the bat. Figure out a way to allow for joint flexibility so you can change hand / finger / joint position after finishing your hand. I did this by using small pieces of stainless steel pin rod with single tack welds to each subsection of finger. This allows for flexibility right at the weld, and allows you to bend each section of the hand into the proper place after finishing the design.

Step 12: Stainless Steel Hand Pattern Development

Getting the flat pattern correct on this design is really important. This was made quite a bit simpler since I was trying to make life sized hands. Here was the general process:

1) Make an Illustator or Inkscape file with the proposed metal pieces
2) Print them out on a piece of paper, and cut them out with scissors
3) Try to fit them to your hand!

When you are looking for fit, pay close attention to areas where the paper wants to snag or grab. You may be able to force those kinds of curves in a sheet of paper, but will have a really hard time doing it in metal. Add relief cuts where needed in order to make life simpler.

Once you've got a really nice hand that you think is going to be simple to make out of metal, take the same paths and put them on the waterjet!

Step 13: Bend the Hands Into Shape, and Weld Together

These metal hands are small enough that I didn't need to use any equipment to do the bending. With the help of a vice, and a couple of friends, we were able to put a nice bend in each of the pieces. Following the bending, a small piece of pin rod was welded to the back of each section to connect all the fingers together. The weld points are slightly flexible, and allow the hand to be bent into a final position.

After completing the hands, they are welded in place on the overall skeleton.

Step 14: Attach the Skull to the Skeleton

I really wish I could take credit for the cast aluminum skull which acts as Zolterno's head. However, I'm a much better tube, pipe, and sheet metal guy than I am a casting expert. This skull was actually made by Josh Dow from Molten Metal Works - he has a pretty interesting Etsy store here.

After purchasing the skull however, I still needed a way to connect the skull to the body of the skeleton. Aluminum cannot be welded to stainelss steel, so I decided to use a threaded connection to connect the two together. I did a fair amount of digging through the scrapyard to find some parts that would work to create a flat surface on the skull, and then allow a threaded connection to stainless steel for a reasonable amount of money. I lucked out on both fronts though.

To create a flat base on the skull, I happened to find a keyway made out of aluminum in the junkyard. Keyways are typically used to cover power outlets or XLR connectors in the ground. I welded the keyway connection together, ground the bottom edges to match the contour of the skull, then drilled and tapped the keyway for a 1/2" NPT connection.

Step 15: Finish the Skull Connection

After welding the keyway into place, I found a stainless steel hose barb which conveniently fit inside of the stainless steel pipe I had used for the body, and was threaded to 1/2" NPT. Make sure to check and see if your hose barb has any gaskets or o-rings before welding it! I didn't do this, and made a really stinky mistake :).

I was able to weld the stainless steel pipe onto the exterior sleeve of the hose barb, then screw the rod + hose barb assembly which would later become the neck into the skull, then weld it to the top of the shoulders.

Note that I used the same style of connection at the head that I did in the elbows - I have a smaller tube in the center of the piece to try and normalize the volumetric propane flow.

At this point, you should have a skeleton ready to go, just primed for fire effects!

Step 16: Make a Streamline Style Booth for Zolterno

Like all amazing carnival games, Zolterno needs a place to stand and be observed! Rather than making a traditional upright box, I wanted to push into one of my favorite eras of design, the streamline era!

Streamline era design is that sleek 1940s look that can no longer be easily duplicated in our vacuum-form-friendly, and stuff-made-from-cheap-plastic society. There are some example inspirational images below...the easiest way I can describe it to people is that there is a single "line" in a piece. A line pointing in a unified direction which all other lines are generally parallel to and/or branch from it to later become parallel. It is the opposite of what a traditional tree would look like :-D. I also really liked this design for this project since it forces a distorted vertical perspective making the piece look more imposing than it really is!

Since there a bunch of constraints that have to be met with this model, I started in a parametric design suite (Autodesk Inventor is my favorite), but you could use a bunch of other things. Parametric modelers are neat because you can change something, and your entire model will update to reflect that change (in a perfect world :-D). Also, like any modeling software, they give you a really good idea of overall shape and form of the end piece.

Step 17: Cut the Frame, and Do a Jig!

The trickiest part about making this frame was ensuring that each piece would have the proper angle and alignment to make my welding job simplest. 

To ensure the angles on the frame were as accurate as possible, I used a waterjet to cut out the overall panel shapes. I made the frame from 1/8" thick steel plate since there were only minimal internal trussing options without blocking the movement of Zolterno himself.

Additionally, a jig was built using an angle measure and a chop saw to allow the correct draft angle to be met when assembling the piece.

Step 18: Cut the Corners for the Enclosure

The corners of the enclosure are rounded, but tapered to a point on top of the structure. To keep the inside of the enclosure as simple as possible (to prevent adding visual clutter in with the fire piece), I did not want to use ribs or other support structures on the inside corners of the enclosure. That means using something which would be simple to slip roll, then simple to cut with shears (like 16ga. steel) would be too thin. Bummer. Time to bust out the fatter pipe.

I purchased some dimensional tubing from my local metal supplier (different than standard pipe - it has a specified outer wall dimension and the thickness counts against the *inside* diameter of the tube...standard pipe specifies internal diameter and measures the other way!) to use as a starting point. 

I tried a few different methods of trying to get even wedges out of it, but the best one I could find was setting up the material with a thin piece of wood to act as a helical guide, then using a plasma cutter to cut the shape I needed. I got the correct wedge profile by clamping the steel enclosure plates to the jig I made in the previous step, then cut the pipes to fit. 

Step 19: Weld the Corners to the Rest of the Structure

Now that you have some wedges complete, it is time to weld them into place.

My technique wasn't the best on the plasma cutting - it was really difficult to get repeatable helical slices (as you cut the pipe apart, its diameter will shift on you making repeatability without using new pipes each time really difficult).

In my case, I solved this problem by doing a ton of grinding after the welding was complete. Definitely boring and time consuming, but it made the end result worth it!

Step 20: Add the Substructure of the Piece

Inside of the enclosure, there needs to be a spot which holds Zolterno himself, but also electronics housings and the thermal protection for them.

First off, I made a protective plate which will not only serve to hide the underlying electronics, but also protect them from thermal damage. I like the look of steel diamond plate, so I used that as my base for the piece. I cut this with an oxy-acetylene torch plus used a guide to keep the edges square. I like to use an oxy setup when the material thickness changes over the course of the my experience, getting the proper movement speed / heat settings with a plasma torch under these conditions is difficult.

Additionally, I made a hole in the center so the lowest section of the Zolterno spine could stick through the diamond plate. I then made a quick stainless steel flange so I could bolt Zolterno to his base at a fixed distance. Additionally, although welding stainless steel to mild steel is possible, it will cause the beautiful stainless to begin rusting, which is something I really wanted to avoid.

Finally, I welded legs to the bottom of the diamond plate. These legs were designed to slip fit into slightly larger round tube on the base of the structure. This makes Zolterno removable for electronics maintenance or retrofit!

Step 21: Make a Sub-base

Why is there another layer to the base? This layer holds the electronics tray. The top layer really serves as a heat / fire shield for the electronics and that is all.

I pretty much used the same techniques as before (oxy cutting torch with guides), but my pattern was much different. First, I knocked out the corners so I didn't have to deal with matching a perfect radius to my plasma cut pipe corners. Additionally, I knocked a big square out of the center which would hold the electronics tray later. Lastly, I welded pipes which would nicely slip fit into the pipes which were welded to the diamond plate above, and the base was ready to be installed!

Step 22: Install the Sub Base in the Piece

This step is pretty simple in the grand scheme of this project, but something that should be said.

The whole assembly made in step 21 was now ready to be installed in the main piece. I grabbed my trusty level to make sure everything was nice and straight, then did a few spot welds to hold it all together. To test it for weight and size, we plopped Huck, the best shop dog in the universe, onto the piece. He seems thrilled. Kinda.

Step 23: Make a Top for the Enclosure

No enclosure is properly finished until it has a slick looking top!

I was originally thinking about making just a basic flat top for this piece, but after I made one and put it on top of the piece, I realized how ridiculous it looked. It carried none of the lines of the piece through, and just looked like an abrupt end to an otherwise beautiful piece.

So instead, I designed a pyramid. (sigh). I hate making pyramids, they are always tougher to make then you think. I'd go as far to say I hate pyramids as much as Indiana Jones hates snakes. Here's my abbreviated version on how to make a steel pyramid (out of thicker gauge material):

Measure each leg of the pyramid on your part itself don't go to your drawing for this! Unless you are the world's best fabricator, chances are, your dimensions are a little bit different than you thought they were. If you use the drawing, it is unlikely your pyramid will fit.)

Calculate where the centerpoint of the pyramid should be based on your edges, and draw yourself a sketch in illustrator of each single slice.

CNC Plasma or Waterjet cut these if you have access to one...or trace the pattern on metal and cut it by hand. Bend any edges that need bending (a bending brake will help you tremendously!) Note that the angle isn't very important here because it is likely some very bizarre number.

Cut yourself a section of pipe which is the overall height of the pyramid you want, and rest the metal pieces on that section of pipe. This will allow you to align each of the pieces without a gap, and fill them with weld!

Voila! A pyramid!

Step 24: Make and Install a "coin Box"

The "on" switch for Zolterno is a small "coin box". Really, it is a simple snap action switch inside of a brass box. When you press a coin down, it hits the switch, and starts the program!

Making this requires you to do some more plasma torching / pattern making and metal bending. Its just like the pyramids, but simpler :).

I'd recommend making this box out of something easily bendable (I used brass). Primarily, this is because when you go to install it in the piece, if there are very hard edges which won't want to move (like 16ga. stainless), it is unlikely you'll be able to get a nice, tight fit with the surrounding case. How do I know all this? Because the first box I tried to make was 16ga stainless and it didn't work out so well :)

Step 25: Enclosure Finishing

The entire enclosure is made from mild steel, and I don't want it rusting on me. Finishing the enclosure was particularly tricky due to the fire element. There are a few options available in this space:

High Temperature Power Coat: Easy to apply, only takes up to about 900F, only really comes in silver and weber grill black :(
Ceramic Coating: Lots of colors available, giant temperature range since these are normally used on exhaust headers. Super expensive, very difficult application and curing process
Firearm Coating (Cerakote)! A decent selection of colors...not all of them look military. Tricky 2 part liquid application, but curing schedule is straightforward. Good to about 1500-2000F.

I went with the Cerakote option, and sent it down to my favorite finishing guy - AJ at West Coast Powder Coat in South San Francisco. He does a fantastic job in a hurry. Although I do some finishing on my own, I usually get a little nervous when it is a tricky finish...I don't really have the best shop layout for finishing.

Additionally, I added perforated stainless steel behind the lettering and attached it with rivets for more contrast...seeeeexy!!

At this point, we have a finished enclosure and all we need is the electronics!

Step 26: Electronics Planning and Control

There are 2 big challenges with the electronics on this project. First, the skeleton weighs quite a bit, so it requires a substantial set of servo motors to drive the skeleon. Second, we'd like to control the servos in an "artistic" way rather than an "arduino" way. We don't care so much about degree increments or the like, but we do care about positional accuracy in the final model. 

There are solutions to both these problems! First, the servos I used are rated to 1600 oz-in (yes, that is 100lb at 1 inch torque) and are sealed to IP66 standards. They cost a pretty penny, but they do a remarkable job. They are from can find them here. I got the pre-assembled pan/tilt assembly to give my marionette 2 axes of control.

On the control side of things, I used a Maestro microcontroller rather than an Arduino. Rather than using a full on scripting language, you have the capability to control up to 24 servos directly from a GUI interface. It works with keyframes instead of commands, so making fluid movements is very simple! Additionally, you can get under the hood and have it drive its servo pins just like GPIOs, so all the relays for fire control, card control, and whatnot can also be controlled. 

Step 27: Electronics Box Layout

Now that we know what kind of hardware we are going to be putting into Zolterno, we can start laying out the electronics box! Power supplies are going to take up a bunch of room. The Torxis servos can pull 3A @ 12V each, the card dispenser takes 24V, and the maestro can have a maximum input voltage of 16V (impressive!). Additionally, I have a relay board to power the fire effect solenoids which needs 5V, and the solenoids need 120V...whew!

Sidenote...if you want to learn more about wiring up propane powered fire effects, check out this instructable that I wrote on the topic.

I have 2 separate power supplies in my box...I'm powering the servos on their own supply to prevent any kind of giant voltage spike from frying my microcontroller.  The other is a triple output 5/12/24V power supply for the micro, relays, and card dispenser.

Make sure to unify your ground connections somehow or else your microcontroller will freak out! I'm doing this at the 120V input plug, and it has been working great.

Step 28: Wire in the Maestro for Servo Control and GPIOs

...its just like your first soldering class, but cooler because you are controlling a marionette and FIRE! :)

Step 29: Light It Up!

OK, if all went according to plan, you should have a fully functional fortune teller which also catches on fire. What could be better?? Hope you enjoyed this...please drop me any questions you have below!