Most laser spirographs consist of only two mirrors, limiting the complexity of their shapes for the sake of easy construction and bulky size. I have seen various guides on the net about three mirror spirographs, and after creating one figured I would up-the-ante: a four-motor spirograph in a compact box which is portable. This design will accept the use of any pen-style laser pointer, and through the use of potentiometers (variable resistors) to adjust the rotation speed of the mirrors, new shapes can be created. The benefit of using a laser beam allows the image to be projected to any size, on an indoor wall, an outdoor tree, through a lake/pool, snow, or the side of a building.
I hope you enjoy creating and sharing this display of light, which myself, friends, family, and strangers alike have been drawn to the limitless shapes created through exploiting human persistence-of-vision.
This is a rather complex mod. I'm already assuming you know how to solder, and have some basic understanding of wiring. Though you definitely could complete this mod as a first project, it will be rather confusing and challenging.
This violet projector made by user JoeMonkey from following this instructable -- Awesome job Joe!
***WARNING - SERIOUSLY, I MEAN IT, READ THIS ONE***
Laser light while very enjoyable can be extremely dangerous, dangerous to the point that most people don't understand the numbers of how powerful 10 mW (milliwatts) is, much less 100 or 500. While many projects have unnecessary warning labels, the concentrated energy from a laser beam really can blind the eyes of those who look into it's beam. Realistically, any laser with a power over 10mW (3.84mW is the power at which human eyes begin to be damaged) shone directly into a persons eye will de-nature (boil/cook) the rods on the back of their retina. This becomes a big problem if a person looks directly at the beam, as their center of vision will be damaged, inhibiting reading and other fine viewing permanently. The damage comes because the lens of the eye focuses light so precisely, what was 10 mW ends up becoming 80mW since it's focused on such a small area of the retina. It sucks to have your vision ruined for life for a toy. That being said, the cheap crappy red laser pointers for $2 tend to output about 0.5mW, and won't ever hurt you.
Second, don't shine a laser at anyone who doesn't want one pointed at them. In multiple states pointing a laser beam at a person is equivalent to assault with a knife. Many people have an irrational fear (thanks to being portrayed inaccurately in movies and television) that a laser beam is associated with a firearm, as such ignorant people fearing for their life can earn you a trip to jail. This includes pointing laser beams through people's windows, their car, or even simply near them, people are fearful.
Third, never point a laser beam at any aircraft or helicopter. These vehicles often use polycarbonate for their window "glass", and a laser beam anywhere on the window will scatter through the entire surface making it impossible to see out. Pilots take laser beams very seriously, and the government crackdown in the United States is especially strong. I personally know a friend who has been given a $1,000+ ticket and criminal record for pointing a 5mW laser at a police helicopter. Though the real life danger for pilots is minimal and over-hyped, government over-reaction to laser beams is not.
Fourth, eye damage from lasers usually happens without a victim immediately recognizing anything ever happened. A single flash from a 100mW might make you flinch and say, "Wow, that was lucky". In reality, you just toasted a line across your retina, but other parts of your eyes will compensate your vision to the point you don't notice. With multiple exposures (though really, a single 200mW+ exposure will truly screw you up), eventually the damage will accumulate, things become blurry, and you can't read.
Now with all the scary stuff out of the way, let's get to building!
Step 1: Parts Listing
Drill Bits (Set of 20 bits: $20) - 1/16", 1/4", 1/8", 3/8", 1/2" drill bits were used in this mod.
Electrical Conduit Box (~$3, Lowes) - Gray box measuring 6" Width x 6" Length x 4" Height. Most are intended as a junction box for pipes that carry electric wires, the one I purchased doesn't have any holes for pipes.
Electrical Conduit Fitting (Pipe Adapter) (~$1, Lowes) - My laser is exactly 3/4" at its front, as such I purchased a 3/4" -> 1/2" fitting. This allows the laser to be inserted into the box without wobbling around, but prevents the laser from falling into the box. Get whatever size fits your laser, only the beam needs to pass through.
Rotary Rasp ($5) - The proper method for drilling a hole for the conduit fitting would be either a hole-saw, or an omni-bit. As an omni-bit costs $50, and I couldn't be sure of the proper hole-saw size to use (each hole saw costs about $10), this cheaper method will do.
On / Off Toggle Switches 4x ($8) - $2 each at Radioshack. A ripoff sure, but they are convenient.
Red Safety On/Off Switch 1x ($4) - The red knob that you see on fighter-pilot joysticks and nuclear briefcases in movies. Complete overkill for this mod, but it just looks so cool!
1.5v-3.0v Hobby DC Motors 4x ($8) - $2 each at Radioshack. You could purchase mini-motors (cell-phone vibrators usually), which have the benefit of higher rpms at a smaller size (but they are usually to long to fit inside a box this small), but less torque and a whole lot of noise.
100 Ohm Linear Potentiometers 1/2 Watt 4x ($6) - These restrict the amount of electricity that can go into the motors, making them go faster or slower. Purchase them online, which automatically adds $4 of shipping. They are impossible to find at any brick and mortar store for low ohm ratings. Most stores sell very high ohmage ratings, such as 1k, 5k, 50k, 100k, 1M, while we want 100. The 1/2 watt rating is strongly suggested, but the motors would likely run anyways with 1/4 watt max. In this guide I initially used 500 Ohm resistors, which turned out to be far too stiff, then I dropped down to 120ohm, and now I suggest 100ohm. By being too resistive, I mean that while the knob in turning from full on to full off may be about 240 degrees of rotation, only about a 30 degree window will adjust the speed, making it really "touchy". I purchased mine from Parts-Express.com
Potentiometer Knobs 4x ($6) - I purchased these knobs from Radioshack. They are decorative knobs, compared to the black and white-lined knobs. Either style works the same. They stick on the turning post of a potentiometer, and a tiny screw in the side tightens down onto the post.
1 Laser Pointer (~$10-$infinity) - For this guide I am using a 150mW Rayfoss laser, which cost $100. Most people can't justify spending so much cash on a light, here are your options.
Rayfoss.com- A respectable Chinese company, the first I recommend for newcomers. Rayfoss sells medium quality lasers for excellent prices. If you have any questions or concerns, e-mail them and expect amazing customer service. They bend over backwards to meet your order needs, and often throw in free goodies if you are friendly.
LEDShoppe.com- A non-respectable Chinese company, but they sell low quality lasers for rock-bottom prices. The quality is still far higher than what you would find at a normal store like Target or Sharper Image. Only purchase the 5mW from here, as their 20mw and up lasers all look the same brightness (they are all the same laser, but they do a POT mod on them to boost the power, resulting in higher amounts of infrared light which helps fake the numbers, green light stays the same).
Novalasers.com - A very respectable American company. Expect high quality for matching prices. They sell unusual lenses and diffractors.
Optotronics.com - Laboratory and military level equipment, ultra-high quality, very high prices. They are excessively overpriced on the low-end (below 100mW), but if you want very high-powered lasers, they are tough to beat.
Dragonlasers.com - Medium quality company. The main product to purchase from them is their laser safety goggles, which are top quality for low price. They have an excellent list of lenses and optics to purchase as well. As any respectable laser enthusiast would say, you should buy goggles since $25 is a small price to save your vision. I personally don't use them unless I'm working with something high powered (over 300mW), and am very careful and aware of what I am reflecting off of, that being said, I'm still only a 1/100th of a second reflection off my eye to go blind.
Wickedlasers.com - Stay away from this company. With good marketing they take advantage of unknowledgable newbies by selling them low quality lasers and gear for insane prices. Don't be sucked in by their flashy videos and photos (which are very misrepresented by playing with photoshop), they also boost their public image by paying people to write extremely favorable reviews of their company. To put it simply, they're a ripoff.
Soldering Iron 15 Watt ($15) - Radioshack, it heats up to about 260 C (500 F) to melt solder.
.022" Silver Rosin Core Solder ($3) - I prefer rosin core as it helps make cleaner welds with minimal effort. Again, available at Radioshack.
Needle-nose Pliers ($5) - Your second most important tool, next to the soldering iron.
18-22 AWG (Gauge) Wire ($3) - The raw wire used to conduct electricity between different parts of the spirograph. Any wire will work, but I find 18 AWG is the easiest to handle. Get a few different colors if you can, I use red, yellow, and black in this mod.
Electrical Tape ($2) - Used to wrap up exposed connections to prevent short-circuits.
Hot Glue Gun ($8) or BIC Lighter ($2) - To melt hot glue. After leaving my hot glue gun on for four hours straight, it exploded and blew the breaker. Now I use a BIC lighter.
Hot Glue Sticks ($4) - This glue will fix the motors in alignment for the laser beam, as well as hold on the external plastic laser mount and window.
Knife ($4) or Wire Strippers ($8) - To remove plastic sheathing from wires. I personally prefer the knife due to being able to remove sheathing which the strippers can't reach in tight spaces.
K'nex / Lego Lifters ($Peanuts) - Use anything 1cm (1/4") tall. These are just hard blocks that lift the mirrors up a bit to not scrape against the case.
2 AA Battery Pack & 9 volt Connector ($5) - Radioshack again, if you can, purchase the battery pack with the pre-attached 9 volt snap on connector. They were sold out so I had to use bare wires to attach my own 9-volt connector
Plexiglass/Acrylic Glass (Optional) ($10/ 2'x4' sheet") - A window for where the laser exits. It's not necessary in any way, and to some extent causes your laser to scatter upon passing through it. I just put on the window to help minimize dust on the mirrors.
1" Diameter Acrylic Mirrors ($5 / 24 mirrors) - I purchased these at the craft store Michaels. I personally chemical treated these mirrors to transform them into "front surface mirrors", meaning there is no protective acrylic layer over the reflective aluminum, but rather the metal is exposed (and extremely easy to scratch) for a perfect reflection.
Sidenote on chemical treating: Purchasing an equivalent front surface mirror would cost $7-20 per 1" mirror. I went to my local automotive store, purchased Aircraft Stripper (chemically designed to not attack aluminum, but requires you to use chemical resistant gloves and be careful when breathing around the spray [brain damage]), to remove the protective gray backing from the mirrors and expose the aluminum. Even with chemical resistant gloves, it would burn through them every 10 minutes or so. This is a rather advanced step that is not necessary, but is highly encouraged to prevent laser scatter and is beyond the scope of this instructable. Google is your friend if you are interested. Process went: Spray stripper on gray adhesive, wait 10mins, wash in hot tap water, rinse with de-ionized water, dry with soft paper towel via pressing (no scrubbing); spray stripper on brown adhesive residue, wait 4 minutes, wash/rinse/dry; spray stripper on remaining residue, wait 2 minutes, wash/rinse/dry, done.