Introduction: Concrete Desk Lamp

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When I started this project I had a specific goal in mind, an elegant desk lamp with a mix of industrial and contemporary design. I wanted to mix concrete and wood to make a simple and easy project.

Materials

  • 15mm by 20mm by 1-meter piece of wood(I am using European beech)
  • 8mm by 16mm by 1-meter piece of wood(^)
  • Filament to 3D print the mold and the shade(I am using black for mold and orange for lamp head and base PLA)
  • M4 wing nuts
  • M4 40mm hexagonal head screws
  • Concrete(I am using a premade mix as I have no prior experience with mixing concrete)
  • Heat shrink tubing
  • Black and red wire
  • 10W LED
  • 100 ohm resistor
  • Toggle switch (the button in the photo was not the one used as that is a momentary switch which would be really impracticle to use for a lamp. Instead I used a toggle switch. The size is pretty standard so any toggle switches would work as long as they look similar.)
  • 12v power supply
  • 3 screws with wide heads(I salvaged these from a DVD player so I dont know where I got them but any screw with a wide enough head works.)
  • Either a 20mmx20mm heatsink or 3 U shaped aluminum profiles of different sizes which can be made into a heatsink
  • 4 small screws 2.9mm wide and 5mm long

Tools

  • Soldering iron(+solder)
  • Drill
  • 3D Printer(I used a Wanhao i3)
  • Bucket to mix the concrete
  • Anything to mix the concrete(I used a drone propeller)
  • A hacksaw to cut the wood
  • A protracter and a ruler to measure my cuts
  • A hot glue gun
  • Strong multisurface bonding glue(should stick to wood, metal, plastic, and concrete)

Step 1: Making the Base

I started this build by designing the mold for my concrete base using fusion 360. I wanted the mold to be heavy enough so that there was no chance of it tipping, while also not being too thick. To achieve this I used these dimensions: 120mm diameter, 5mm filet on the top, a 20mm wide grove through the base 15mm deep, 40mm tall.

My initial design was different but I changed it after I realized the wood I wanted to use was too large for a lamp.

STL file

Once the mold was printed I screwed the two sides together with 4 screws. I then used olive oil to coat the sides which I hoped would make it easier to remove from the mold. Next, I went into my workshop and measured out roughly 450 cm^3 of concrete mixture and 50 cm^3 of water. I mixed them together but when I was done the concrete felt more like wet sand then something that I could pour. I added more water to remedy this and when it was homogenous I poured it into the mold. Per the instructions on the bucket of concrete I got I waited 3 hours before removing it from the mold but when I did a piece of it had cracked and the cast had been ruined.

I came back the next morning to recast it in the mold following the same process. This time however I left the concrete to dry for 24 hours before removing it from the mold and waiting another 24 hours for it to fully set. This is because I suspect the concrete cracked because my workshop hovers between 12-15 C° and the reaction was slower. When I finally took it out, it didnt fall apart but around the corners of the slit, small peices of concrete were falling off.

I decided to try again but this time I added less water so the mixture was more clumpy, and once I had poured it in, I used my makeshift spatula to push concrete into the corners so it would stay put and there wouldnt be any gaps. I then decided to repeatedly drop the mixture from a few centimeters up to knock any airbubbles in the mixture out. Then I placed the mixture in a drawer and waited 48 hours before opening it up. This time it worked and the concrete came out intact.

Step 2: The Wood/Plastic Part.

1. I started this off by cutting a 20° angle into the 15*20mm on the 15mm sidepiece on one end. This will give the column a slight angle to hang over my desk. I used a hacksaw for this step but using a router or a laser cutter would be more accurate and faster.

2. I then using fusion 360, designed 2 almost identicle peices for the base of the lamp. They would hold the wood in place, but also contain all the wires, and the resistor, and switch. These files are on Thingiverse. On the peice with the round hole, insert the switch and secure using hex nuts.

3. For the other peices of wood, namely the ones that actually hold the light, cut 2 peices of the 8x16mm wood 280mm long. Then about 6 cm from one end, drill a hole through both peices on the 16mm side.

4. Drill a hole near the top of the 15x20mm wood on the 15mm side.

5. Now attach both peices of the 8x16 wood to the 15x20 mm wood with the hex nut and bolt.

6. Finally, drill a hold near the bottom of the wood from where it meets the top of the plastic to the bottom as can be seen in the photo and cut a slit into the wood by making 2 diagonal lines at the bottom. This is needed to attach the wires

Step 3: Wiring

  1. Cut three peices of wire similar in length to the photo at the top.
  2. Take the switch out of the case to avoid melting it accidentaly
  3. Connect the wires as seen in the photo, 1 wire going to the central lead, another spanning the 2 leads on the edge so that the switch can be flipped either way, and a third going to either lead on the side.
  4. Once completed, put the switch back into place and melt hot glue onto the leads to prevent any short circuits.
  5. Cut the plug off of the 12v power supply and push the wire through the back of the other 3D printed base peice as can be seen in the photo. Strip the wire and determine which side is positive and which is negative by using a multimeter or a diode such a smaller LED
  6. Attach the positive lead to the 100 ohm resistor and solder them together, then cover with heatshrink tubing. Next connect the other side of the resistor with the wire going to the central lead of the switch and solder together, again using heat shrink tubing when done. Connect the wire coming off of the switch that hasnt been connected and connect it to a long peice of wire that will be attached to the head of the lamp by soldering it. Dont use heat shrink tubing as it wont fit through the hole drilled into the wooden peice and there are no other exposed wires.
  7. Connect the negative lead of the power supply with another long wire by soldering it and using heat shrink tubing.
  8. Pull both of the long wires that are connected to the power supply and pull them through the hole drilled into the wood. Once this is done, we can seal up the base of the lamp by using multisurface glue.

Step 4: Assembly

  1. To make sure that our LED doesn't burn out, we need to add a heat sink. Since I couldnt find one and ordering one would take a while, I decided to build my own. I went down to my hardware store and bought 3 U shaped aluminum profiles, each bigger then the last. I then measured 20mm on all 3 peices and using a hacksaw, cut them off. I then used the multisurface glue(thermal paste would have worked better) and attached them so the smaller ones were nesting inside the larger ones.
  2. I used the small flat 3D printed peice to mount the LED. I placed the LED inside and pushed it in and it fit quite snuggly. I then used some glue around the edges to bond them together well. I then used the same glue to attach my heatsink to the top of the LED.
  3. Once the head of the lamp was printed, I removed all of the support. I then placed the LED and the heatsink onto the mounting plate of the lamp head and screwed it in using the 2.9x5mm screws.
  4. I pulled the 2 wires coming from the base of the lamp and using scews with wide flat heads, attached them to the wooden frame at regular intervals. This ensures that the wires will stay put.
  5. I then drilled a hole into the lare area on the top of the head of the lamp. This is where I will attach it to the frame. I also drilled 2 more holes into the 8x16mm wood near the other end(where the other holes are). I then used another bolt and wing nut, attached the head of the lamp to the wooden frame.
  6. To finish the project, I places a peice of red and a peice of black heat shrink tubing accordingly. Then I removed the wire that I wouldnt need, stripped the end, and attached it to the LED on either side with solder. Once this was done I used the heatshrink tubing on the solder joint.
  7. Now the lamp should work. :)