MAKING @ SEEED VOL 6: An Engineer’s take on the LM317

Making & tinkering is the DNA of Seeed. Apart from our internal hackathons, some Seeeders are also embracing parts and bits off hours by our own when we get inspirations. To share our tinkering with the community, here we are: a new column Making at Seeed is live.

The projects we’ll share in this new column might be really entry-level, but we just want to share to learn. So please don’t hesitate to leave comments or suggestions as your inputs and feedbacks will help us do better.

Today, let us introduce Nicho, an application engineer at Seeed’s R&D team who will share with us his journey in his project: to make a giant version of the LM317, an adjustable three-terminal positive-voltage regulator made by TEXAS INSTRUMENTS, as a reminder of his university days.

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LM317 is a modern adjustable positive linear regulator that has a long-standing and rich  history. It is probably one of the most exciting parts that I have ever encountered during my university days and I frequently found myself burning it due to my lack of expertise in younger days.

One day, I suddenly had the urge to create a giant sized replicate of LM317, and stayed at Chiahuo x.factory (a makerspace and Fabl Lab powered by Seeed) over the weekend to create the product.

Firstly, I used a 3D design software to draw a 3D reference model of the prototype and edited some details of the design. In the later half of the process, I continuously referenced to this 3D diagram during the manufacturing process

The second step was using x.factory’s laser cutter to create the part. Since I chose a 3mm thick wooden board, I had to decide on the size of the pieces that I wanted to cut it into based on the size of the final product. I decided to cut the board in 10:1 ratio (with reference to the diagram) to get the smaller pieces, with each piece being around palm sized. In the next step, I used the 3D diagram as a reference to draw a 2D diagram, and used the CAD to start the laser cutting process.

Operating the laser cutter

After waiting for the glue to dry for a day, the clamp was removed and I went to buy some of the materials needed.

The materials that I used for this project include:

  • Matte black spray paint
  • Shiny silver spray paint
  • 502 glue
  • Working gloves
  • Polishing wheel
  • Masking tape
  • Some waste paper

Combining the 2 different pieces (which I glued yesterday) together
Each piece is carefully polished by the polishing wheels

Rough polishing completed

Next, further polishing of the product with the second polishing wheel is done.

After polishing the different parts, it is time to paint them! I used masking tape to wrap the 3 protruding portions so that they do not get sprayed by the paint.

After polishing the different parts, it is time to paint them! I used masking tape to wrap the 3 protruding portions so that they do not get sprayed by the paint.

When spray painting, the key is to be patient and spray in an even and controlled manner. But since matte black is not that obvious, you don’t have to spray it that carefully…

After spraying the black portion, we wait for the paint to dry.

Then spray paint the heat dissipator part silver

After the black paint has dried, remove the masking tape from the 3 protruding portions

Using the masking tape to cover the black portion, the 3 sticks are spray painted silver.

Finally, we used laser cutting to make a stencil of the logo and design, which we can then use to spray paint the logo on the product.

The original plan was to put a real chip inside and connect it with wires. However, due to some difficulties in finding the iron piece for the pinout, I decided to scrap the idea in the end.

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July 2019