Here is a frosted acrylic lamp shade that fits on an Ikea light cord. The design is something between a flower and a klingon bat'leth, just like you always wanted. You're welcome.
This instructible focuses on the design process, but I've also included the file so you can build your own!
To make this lamp shade you will need:
- 24" x 16" sheet of 1/8" acrylic - $25
- a laser cutter
- superglue or acrylic glue
- an Ikea Hemma light cord - $5
- shade material - I used a sheet of 20"x26" Vidalon vellum - $2
- dish detergent
- sand paper (400 ish)
- 200 lumen light bulb (the equivalent of a 25 watt incandescent bulb)
Step 1: Draw the Profile Curve of the Lamp
I sketched some curves in my notebook, then traced them in Rhino. I used the edit points to adjust the curves, you can see the iterations. I then scaled the curve to the size that I wanted, less than 1 foot by 2 feet. I modeled a standard light bulb for a sense of scale and proportion.
Step 2: Design the Light Fixture Mount and Output the Laser Cut File
The profile curves will attach to each other and the light fixture via some notched rings. Here's a previs of what the lamp design is so far.
This lamp shade is designed to fit the Ikea Hemma 15' light cord. The interior diameter of the rings needs to be wider than the threads of the fixture (measurement A) but smaller than both the screw attachment (B) and it's stop point (C). The exterior diameter needs to be wide enough to accommodate the profile joint/notches and clear the attachment (B). I decided on 1 5/8th" (1.625") for the interior diameter and 3" for the exterior diameter of the ring.
This is designed for 1/8" acrylic, so that's how wide our notches will be. Don't worry about leaving a tolerance: acrylic sheets are actually a little thinner than their list dimension. Also, the laser cutter makes the cut slightly wider. 1/8" notches give us just the right amount of play for assembly. Finally, I add little slits for the vellum shade pieces to go in. They are only 1/32" wide.
Set the lines you want to cut with the laser to red (exactly red, not just any red). Set any lines you want etched to blue, and guidelines to yellow. Repeat the parts and layout the design to fit the sheet of material. I got the design to fit within a 24" x 16" rectangle and cut the design from a 32" x 16" sheet. Export the Rhino file as an Autocad (.DWG) file. I set the output to 2004 Polylines. The Rhino and DWG files are attached.
Step 3: Laser Cut It!
This is the best step.
Set the laser cutter settings to suit your material type and thickness. The Universal Laser Systems laser I used has presets for different materials, you just have to pick the material type. You can see that the material is Plastic > Acrylic > Continuous Cast Acrylic. I changed the thickness to .125." Remember, the thickness determines the laser focal point, so if you are concerned about the laser cutting all the way through, increase the intensity of the laser, not the material thickness.
For this design I chose frosted acrylic. For best results with light colored acrylic, leave the paper on both sides or at least the bottom to avoid burn marks. Unfortunately paper is not allowed on the laser I used, so it left some burn marks. If you want to get rid of them you can sand them off. I washed the parts with regular dish detergent as well to keep them from stinking up my hands and work space.
Step 4: Put the Rings on the Light Fixture and Assemble the Profile Pieces
Now we turn the 2d parts to one 3d object:
One ring goes on from the bottom and the other 3 from the end of the cord. Screw on the bottom fixture piece, and viola! We have a secure mount.
Now, glue the first profile piece on. I used Maxicure, but any superglue or acrylic glue will work. I wear gloves because I hate the feeling of superglue on my skin. The first profile is the trickiest one. Hold the parts for 20-30 seconds for them to set. You can brace it with another unglued profile piece in another notch set to stabilize the fixture while you glue.
Step 5: Cut and Add the Shade Pieces
I initially designed and laser cut some shade pieces to fit into the slits in the profile pieces, but there's some imprecision in the assembly and the pieces didn't fit well. The shade pieces look best when taut, so I did it by hand.
I used about half of a 20"x26" sheet of Vidalon vellum which has particularly good transparency. I used superglue for this part as well, since I have it and it bonds the vellum without warping it. Be sure to use a glue bottle with a fine tip.
The shade is more decorative than utilitarian, I suggest a dimmer bulb than the 400 lumen bulb included.
Before adding the shade pieces, screw in the light bulb.
Cut six strips of vellum of each of these sizes:
- 1 1/2" x 6 1/4"
- 1 1/8" x 6 1/2"
- 1" x 6"
- 7/8" x 5 1/4"
- 5/8" x 4 1/2"
- 1/2" x 2 3/4"
- 1/4" x 2 1/2"
The length is not so important, you just need an extra inch for gluing. If you are designing, the strips are about 1/8" thinner than the length of the slit.
Going around the circumference of the lampshade one row at a time, thread the velum through the slots. Glue the vellum to the adjacent piece. Apply the glue sparingly, wait about 30 seconds for it to dry. Since the ends help hold the pieces in place wait to trim them until you have finished a whole row. On the last connection of a row, hold the vellum taut while the glue dries.
Ta-da! You now have a lamp shade. Hang your lamp up and enjoy.
Step 6: Redesign Considerations
As you have probably realized, you now cannot remove the shade from the lamp cord, nor can you change the bulb without removing and redoing the paper shade pieces. The bulb that comes with the Hemma is rated for 15,000 hours so that's probably ok.
The super sharp points of the design look very elegant on the screen, but they don't turn out as well on the laser cutter. The tips are fragile and warped because they are so thin. I would round them off just a little for better results. If you agree and used the included file, you can sand them off with a Dremmel tool.
The slits for the shade pieces should be at a steeper angle to block the light better.
I want to try printing on the shade pieces for some color.