We built this Dragon Head Wizard Staff for my girlfriend's 9 year old son, mostly out of parts we had lying around. It uses an accelerometer to "cast spells" based on the direction you shake the staff, or by stomping it down. It uses an ATMega 328 with the Arduino bootloader, and an Adafruit WaveShield for the sound output. The dragon head was hand carved out of lodgepole pine, and the staff was a piece of aspen. The plasma globe came from a kid's toy "Thunder Globe" we picked up at the county fair.
There are 8 runes along the length of the staff that light up when the wizard is about to cast a spell, and flash when the spell is being cast.
Please consider this more of a build log than a literal step-by-step guide, for this was a mostly last minute endeavor built in 4 days, and as such there are a number of things I would do differently if I were to make another.
Step 1: What We Used
For the Dragon Head:
2 Blocks of dry Lodgepole Pine
2 Acrylic spheres from a kaleidoscope
1 Small Speaker
2 Red LEDs
1 Thunder Globe plasma ball
For the Staff:
Assorted small LEDs
Clear 5 Minute Epoxy
For the Main Electronics:
ATMega328 w/ Arduino Bootloader (or any Arduino Compatible)
3 axis Accelerometer
Amplifier Circuit taken from an old pair of computer speakers
2 9v batteries (chosen purely for size reasons, definitely not the best choice for powering a project of this nature)
3 NPN Transistors
1 6mm Tactile Switch
1 N-Channel MOSFET
Small wooden bowl
2 3" long 6-32 machine screws and nuts
Thick wooden dowel - 2" long max
Small piece 3/8" plywood
Step 2: Carving the Head (rough)
We first started with two blocks of wood, penciling in a rough drawing of our dragon with the globe in it's mouth. We mostly carved one side first, then carved the other to match. Occasionally the two sides would be worked on simultaneously as described below. We would often re-pencil in our rough shape as we cut, just to help us keep our bearings.
Using a small carving chainsaw with a carving bar, we first hollowed out for the area in both blocks for the globe and speaker. We only used the chainsaw for the preliminary rough cuts to remove the material as quickly as possible... you could easily do these steps without a chainsaw if you don't mind taking more time.
Once we got the area hollowed out for the globe, we knew with more certainty where the teeth and eyes would be. We then temporarily joined the two pieces while we cut out the rough profile with a band saw.
With the profile roughly cut out, and the two halves still joined, we took the chainsaw to it again to remove more excess material around the horn and eyes.
We then separated the two halves, and switched to a die grinder with a pear shaped carbide burr (see photos) to help finalize the shape... It seems half the battle in wood carving is determining which tools to use and when, and these pear shaped bits are a life saver! I wish I could recommend a vendor for these bits, but our current supplier was just taken over by another company and is in a state of limbo. Let me know if you may know of any good vendors of carbide cutters! :)
The teeth were carved last, for they were the hardest to get exact... we started by carving out the gum line, being careful not to remove too much material around the globe cavity. As we slowly worked our way to the mouth cavity, the teeth became more apparent as to where they should go. After we cut the teeth of one side, we matched them on the other.
If you are new to wood carving, don't let the fear of making a mistake to stop you from giving it a try... Wood is a very forgiving material compared to something like stone. If you're planning on painting your final product, you can pretty much correct any mistakes by simply cutting off the mistake, glue on a new piece of wood, and re-carve it when it's dry. Paint and some filler will work wonders. You may at some point encounter voids or rot in the wood, and just cutting it out and replacing it is frequently the best option.
After we had the rough shape for the two halves of the head, we were able to move on to the detail work.
Step 3: Finishing the Head
We used a Dremel with various small cutting burs to carve the scales and other details. We also sanded the teeth down nice and smooth, as well as clean up any rough edges.
Once the details were carved, we painted it with acrylic paint, and covered it with antiquing glaze at the very end to give it a more aged look.
The eyes from the kaleidoscope were held in place with a couple dabs of hot glue, and the speaker and red LEDs were positioned and then held in place with hot glue as well.
I didn't get any photos of the mounting of the thunder globe in the mouth, but the globe and it's accompanying electronics were held in place with a couple of zip ties that were screwed into the head to hold it steady.
Step 4: Carving the Runes and Wiring Up the Staff
Using a paddle bit with a bunch of extensions, we drilled a hole down the length of the staff for the wires. Then we used a Forstner bit to hollow out the first few inches to hold the accelerometer and to hold the dowel rod that will hold the head and pedestal on to the staff.
The runes were routed out with a dremel, then wired with LEDs. To get the whole rune to glow more uniformly, we filled them with epoxy, then sanded the epoxy back down to match the surface of the staff. (make sure the wiring holes are filled before pouring in the epoxy, otherwise the epoxy will drain into the wiring hole you drilled) When mixing epoxy for this purpose, the light glows better when you have tons of microscopic bubbles... I found that by vigorously mixing the epoxy, it aerates the epoxy with lots of tiny bubbles and helps disperse the light better. Big bubbles are no good. Be sure to test your LEDs frequently when doing this, for once you pour epoxy into the holes, you can't easily fix any problems.
We put the tactile switch next to a bump in the staff where a branch protruded to make it easy to locate by feel. Hot glue holds it in place. We programmed the Arduino so that this switch must be pressed for any spells to be cast.
We screwed the accelerometer breakout board to the bottom of the cavity that was drilled in the staff with the forstner bit, and brought all the wires for the LEDs and accelerometer. These all go to the Arduino which was put into a pedestal (made from an old teak bowl) between the Dragon head and the staff.
Step 5: Squeezing in the Electronics
The head of the dragon was just a little too small to hold all the electronic components and batteries, so we opted to make a pedestal out of an old teak bowl we had lying around. The Dragon head was then mounted on top of this pedestal.
We stole an amplifier circuit out of an old pair of computer speakers, and wired the power to the microcontroller from the same power switch. I chose to run 2 9v batteries due to space considerations, but 9v batteries are really weak, and as such were not the best choice. If you have the space, I'd suggest trying AA or rechargeable.
You will notice in the photos we didn't use an actual Arduino board... I had a couple of ATMega328s with the Arduino bootloader flashed onto them, and opted to use one of those instead... The only major difference is you need to regulate your own power, as well as needing some form of FTDI cable to program it. (not to mention solder it up) If you have an Arduino board and can fit it in your space, it can save you a lot of time to just use that.
We made a bottom for the bowl out of 3/8" plywood, and screwed on a small length of thick wooden dowel to slide into the hole you bored into the stick in the previous step (with a notch cut out of it to make room for the cables to pass). I wired in two white LEDs pointing down that will flash with the sound effects when a spell is cast. (It made for a nice 'lightning' effect)
The bottom plate was held onto the bowl via 2 long 6-32 machine screws, and nuts were epoxied into the top of the bowl for the screws to thread into. (see photos)
The dragon's head was quite simply screwed onto the bowl with 3-4 drywall screws, and the wires for the speaker, eyes, and thunder globe power run through the top of the pedestal.
Batteries were held in place with zip ties screwed to the bowl. This later proved to be a pain when changing batteries, for the pedestal had to be unscrewed to gain access. If I ever get around to improving it, battery choice and access are the two biggest changes I'd make.
Attached is a PDF of a quick schematic I drew up in Fritzing. I didn't include resistor values for the current limiting resistors on the LEDs... you'll obviously need to calculate those based on what you use.
Step 6: Can't Forget the Code!
Attached is the Arduino sketch. It is not commented very well at the moment. Once I get around to writing some better code that is properly commented, I'll upload a revision.
We finally had a working staff that was doing most of what we had envisioned by around 4:30 pm on Halloween day. Nothing like waiting til the last minute to get something done. ;)
Step 7: Smite Your Enemies!
Finally it's time for some Trick or Treating, and some good old fashioned zombie killing!
We would like to put in a special word of thanks to Limor Freid (Lady Ada) and her team at Adafruit Industries... It was Lady Ada's tutorials that rekindled my interest in electronics. The incredible information and tutorials at Adafruit.com are really what made this project possible. :)