I am developing a project for people with 3D printers who are looking for a functional design they can use around the house. The project is a LED lamp module that uses power from a USB cable. The module and a switched cable will be available on eBay at low cost with mounting screws and a lens. That will be accompanied by a series of free designs for different type of lamps posted to Thingiverse for people to download and print out to go along with the lamp module.
The process of designing an prototyping the lamp module will be the focus of this post.
In developing the lamp module there were at least 11 goals, which is a lot for a simple little light:
- Small size–a smaller module would mean smaller and thus faster prints for the end user.
- Low cost–I wanted to make this as accessible as possible, not to mention appealing for purchase.
- Minimal part count–fewer parts keeps cost down.
- Design for manufacturing–although I will be hand assembling these, I want to use manufacturable components such as surface mount electronics.
- High light output–the brighter the light, the more useful it will be.
- Neutral light color–since this may used as decorative light that shines through a 3D printed part it was important to keep it a neutral color (around 4000k color temperature).
- Good light dispersion–a nice wide field for decorative use but an even narrow beam for reading or task lamp. An accessory lens provides this flexibility.
- Appropriate power consumption–I did not want to exceed the 500mA limit for computer sourced usb, although I will not be encouraging people to power this from a computer.
- Acceptable heat generation–a bright LED in a small package generates heat concentrated enough to melt a 3D print, which is obviously unacceptable.
- Flexibility for different applications–I wanted to keep the type of lamp the module would be useful in as open as possible.
- Ease of use–I wanted to come up with a lamp module that could be attached to a wide variety of 3D prints with minimal hassle.
It took a couple of months of tinkering with LED modules, heat sinks, resistor values, circuit board designs, usb jacks, lenses, and even types of mounting screws to come up with a final design. The big bear was #9, heat generation. It took a combination of juggling all of the above plus the design of the 3D printed mounting ring to arrive at a lamp module that would not melt PLA.
The final design is certainly not perfect but functions well enough that I ordered 50 PCBs and 50 sets of components to make up a batch for testing and test marketing.
On to the lamp designs for 3D printing…………….