Laser Cut Constellation Projection Lamp

The Premise

Being very fond of astronomy, I have always wanted to have a constellation lamp. However, current ones on the market either have a few constellations or none at all (just have random points of light to represent stars). In addition no models we saw were meant to be relatively accurate to the sky above you.

We wanted to build a lamp which had the following features:

• All the major Northern sky constellations
• The stars in the constellations to have different sizes relative to their actual brightness in the sky
• Constellation placement to be as accurate as possible to the night sky
• Include nebulae, or other dust clouds with interesting color projection
• Rotate slowly and quietly
• Provide enough light to have bright projections but blocked out any excess light to increase definition.

The system had be broken down major sections

1. Panels
2. Base
3. Electronic Guts

Team Members

• TheDankDrank
• TaylorLu
• TheBigSuleskey

Tools

• Access to Laser Cutter
  • High accuracy holes as well as connection lines without cracking the acrylic
• Dremel or other Rotary Tool
  • Trimming rough edges and precision sanding
• Soldering Iron
• Power Sander
• Jig Saw
• Hot glue gun
• Fan (optional; to help blow away fumes from epoxy and silicone)

Software

• CorelDraw X7
  • Great for creating hairline structures used in vector cutting
• Retina Engrave v4
  • Controller program for the laser cutter used and is different based on the manufacture of your laser cutter

Materials

• Acrylic Sheet
• Epoxy Glue
• Gorilla Glue
• Lazy Susan bearing 4"
  • for the rotating gear
• 50W 12V Halogen Bulb T4 bulb
• 120V to 12V AC Transformer
• 4 Diodes (1IN4004)
  • Used to build a Bridge rectifier
• 12V Computer fan
• Acrylic Paint
  • Normal Black
  • Translucent Mosaic paint for the nebulae
• Stone Tiles
  • 3" x 6" Limestone
• 1/2" Plywood
  • Used for Base Box

If you do not have access to these tools, there are alternative methods to creating all the pieces themselves. In lieu of a Laser Cutter, the holes for the stars can be drilled (however another material is suggested as acrylic is not very easy to machine or work with).

The Materials list includes items which can be found at local Hardware and Art Supply stores. The decorative stone base is optional.

Safety

It is always good to mention the importance of safety.

• Laser Cutter
  • Use a Laser Cutter only with proper training and supervision
  • Follow all of the recommended guidelines for operation of a Laser Cutter
• Dremel
  • Wear safety goggles and proper protective equipment
• Silicone/Epoxy
  • Try to not breath in the fumes while applying

Only use hazardous tools with a person nearby, you may be experienced, but accidents happen and you do not want to be a statistic.

The design of the lamp was essential to making a light which performed to the standards of our imaginations.

It is important to note the following concepts in our design:

1. The size or number of the lights used changes how light rays move through the holes and gaps which are imprinted. (Shown in picture)
2. Since painting the inside of a sphere is difficult (not to mention trying to laser cut it), we chose to instead create an approximated sphere out of acrylic and assemble the pieces afterward.
3. Visually understanding a projection from the inside of a globe is fairly difficult so we used a print and fold version of our shape to find the correct size and orientation of the different constellations.
4. No constellation exists on more than 1 panel. This is to allow the stars to always have the same spacing regardless of room size and wall distance
   • Some constellations were slightly distorted in order to fit them in a single panel and maintain their relative size.

Increasing the number of Panels

A sphere can be approximated by an increasing number of planes it is made out of. Initially we wanted to use a dodecahedron. We decided to increase the sides from 12 to 20 to make a icosahedron (or as some may know it a d20).

This allows for:

• Smaller angles between the triangular plates removing the need to bevel the edges to be able to connect them together.
• A flat bottom plate without having a flat top face
• The ability to somewhat paint across plates to have some degree of continuity.

Designing the Plates for the Laser Cutter

1. A layout of 24 triangles (20 for the lamp and 4 spares) was made in Solidworks
   • 16 plates for 26 constellations
   • 3 contain only Nebulae
   • 1 is the Base for which a gear base was cut into
2. This was imported in CorelDraw and a Star Map of constellations was laid out below it.
   • A constellation map was used so the sizes and locations of each constellation was kept as accurate as possible while drawing out the lines and circles (shown in picture)
   • After it was drawn out the image was reversed so when printing the side that we wanted to keep glossy was face down to protect from any haziness created by the laser.
3. Uniform rectangle sizes were drawn to represent the constellation lines while 4 different diameter circles were used to represent relative star brightness.
   • The size of the circles can change according to personal preference
   • The sized used here ranged from 1.8mm thick rectangles and diameters of circles that were 3.75, 4.3, 4.75, and 5.3mm
4. The print and fold d20 was useful in laying out the orientation of the constellation and creation of a numbering system to know how to rearrange the triangles after cutting and painting.
5. Solidworks was used to design the gear base plate of the lamp with the hole for the light and motor to spin the lamp with.

1. Remember to review all safety precautions before using the laser cutter.
2. Make sure to reverse your image after drawing it.
3. We chose to cut the constellation pieces first so painting could be started right after.
4. Then a separate piece of acrylic was put in to cut out the bottom plate with the gear hole and small gears for the motor.
5. Wipe off the dust particles after removing the acrylic from the laser cutter.

We used two separate thicknesses of acrylic. All panels were made out of 0.08" thick acrylic except for the base plate which we used thicker sheet at 0.25" to increase the support around the gear teeth.

Painting of the lamp was used with black acrylic paint and different color glass paints with use of a sponge brush. A choice was made to not paint the interior of the circles and constellation lines, and only on the inside of the panel. If wanted the interior can be painted, but the decision was made not to because it sometimes made the circles and edges of the constellation lines distorted. The side of the panel facing inside of the globe was painted with black because we wanted the outside have the glossy acrylic appearance.

Black paint was applied beforehand while leaving empty spaces for nebula because we found it to be more efficient to do it in this manner. It is essential to practice painting nebula beforehand so you understand how the paint blends and moves. Only three colors were used for simplicity, but more than four colors can be used if wanted. Make sure to constantly view the opposite side of the acrylic to see what the nebula would look like from the outside of the lamp. In some occasions it can be beneficial to paint while looking from the outside of the acrylic. It is good to practice varying the thickness of the glass paint to see at which you like the appearance best, also to apply different colors in layers while drying in between each one for different effects, and practice blending colors together within nebula. The sponge can be used to give more of a "dust" effect within the nebula. *Remember, the first layer of paint will be the top layer of paint you see once it is flipped over, paint the layers you would want on top first.*

Steps:

1. Practice the following on a spare piece of acrylic with example pre-cut holes and lines:

• Painting black over cuts to find out how hard you need to press to make sure black paint doesn't overflow into them
• Painting black to make a shape of the wanted nebula
• Painting nebula within the outlined black area and check with lights to see how the colors will look once projected on the walls

2. Once you feel comfortable painting, start applying your first layer of black paint to the cut acrylic triangles leaving room for nebula.

3. After the first layer of black paint is dry start painting the nebula while constantly checking to see what it would look like from the outside.

4. Once the nebula are done being painted check with lights to see if any extra layers will be needed.

5. Paint 2-3 more layers of black to ensure no extra light will come through when the lamp is on.

This portion requires all of the electronic materials listed.

Build a bridge rectifier to turn AC into DC for the computer fan. We used a microwave turntable motor because of its low speed and the fact that it automatically switches directions if caught. A small gear printed for the turntable applied to the large gear on the base further decreases the speed of rotation for a very slow spin. We also harvested the Transformer used for this motor as it used an uncommon 21V circuit. We attached the 120 to 12V DC transformer to the head of the wall plug as well to provide power for the light bulb. Since this already provided 12V we could easily use the brigde rectifier her to create a 12V DC circuit for the fan.

Because the lamp needs a bright, pinpoint source of light, a halogen bulb was chosen.

The base is 2 separate parts:

1. A wooden interior for ease of drilling and attachment
2. A decorative stone exterior

The inner wooden pieces are created by 6 panels. The top and bottom of which have holes to facilitate the fan airway and the pathway in which the light bulb enters the icosahedron lamp body.

These pieces were gorilla glued and nailed together. The top and bottom fit snugly, and were tapped into place by a hammer. The transformers were glued into place with Hot glue around the edges. The fan was nailed over the bottom hole to facilitate outtake of hot air generated by the halogen bulb.

A small divot was cut in the edge of the bottom hole for the power cable to pass into the base. Small legs were made out of 0.5" acrylic squares to give the fan some distance from the ground.

The tiles were glued onto the wood box in the same pattern and had a fairly tight fit. We taped the tiles to the wood to help them dry in place.

1. The panels were laid out in the order of the paper d20 made before.
2. The top and bottom 5 panels were taped together and then set in a bowl to apply epoxy to the joints on the inside.
   • Tape was used to help insure the correct angles were kept
   • A bowl was used to help keep the correct shape while putting slight pressure on the panels when applying the epoxy.
   • Epoxy with a dry time of one minute was used first so we did not have to hold it for 45 minutes once the silicone was applied. Epoxy alone is not strong enough to hold the panels together.
3. After epoxy was applied the panels were taken out of the bowl and flipped over onto a flat surface to make sure they held the right shape while drying.
4. The 10 remaining panels were taped together into their ring shape while waiting for the epoxy to set.
5. The panel with the base was epoxied on the outside as well to make sure it held.
6. Once the epoxy set one of them was placed on top of the ring of panels and silicone was placed on the edges of the outside and let set for 45 minutes.
7. After dry silicone was applied to the inside of all panels and then put all together to make the d20.

Route the light bulb and turntable motor through the base. Place the turntable motor into the upper hole and place the gear on the motor. We used 2 gears stacked to make sure the base aligned at any level. The light was just routed through a small gap in the side.

Mount the lamp on the lazy susan ball bearing slider (not pictured). Apply some hot glue to lock the outside ring, making sure the gears fit together snugly.

Power it on, and take some pictures!

Recommendations

• Due to the amount of heat the halogen bulb produces, it may be advantageous to look into multiple LEDs where non direct light is blocked so each panel or group of panels has a dedicated LED
• The base can be made however you like, however, if we were to do this again we would make a triangular base to better match the overall design scheme.
• Liberal use of hot glue can make loose connections or exposed wires non problematic without much effort.
• It is recommended to increase the number of nebulae as they really give alot to the overall feel the light gives off.
• Spend a decent amount of time testing the laser cutter and painting on spare acrylic as these steps arent reversible once they are completed.