Customizable LED Sign

Wouldn't it be amazing to have an LED sign that spells whatever you want? We thought so too! We are Krishiv, Shreeansh, and Srihari, students at Irvington High School. All three of us are in Ms. Berbawy's Principles of Engineering (POE) class, and we have been working on this LED sign as our SIDE project.

We were inspired by Neongaga's customizable design and wanted to see if we could make our own sign to put up in our teacher's classroom.

Big thanks to Fusion 360, Adobe Illustrator, and most importantly, Ms. Berbawy and Berbawy Makers for making this possible.

Tools

• Laser cutter - ULS VLS3.50 Laser System
• 3D printer - We used a Prusa XL and Prusa i3 MK3S+
• SLA Printer - We used the Formlabs Form 3
• Wire cutters and strippers
• Fusion 360
• Adobe Illustrator
• Soldering Station

Materials

• Masonry screws (These are for cinder blocks, check if these will work with your walls)
• 3 sheets of 24"x12" black acrylic 1/4 inch thick (and some scrap)
• Cuttable and individually addressable 5V LED lights (One spool lasted us about 15 letters)
• Acrylic cement
• White filament (1 letter ~ 100 grams)
• PETG filament
• Double-sided tape (This one works very well for us)
• 22 AWG Solid Core Copper wire
• 4-foot conductive rod X 2 for each board - (Any diameter will work just adjust the CAD accordingly)
• Pigtails to USB-A
• Tough 1500 SLA Resin
• Solder
• Tip Tinner
• Flux

The first step was to decide on a phrase. Although this sign features replaceable letters, it is good to have a place to start.

For designing all of our CAD models, we used Fusion 360:

We used the phrase: "BERBAWY'S BADASS BABIES," one of our classroom catchphrases.

• We made it all CAPS so each letter is the same height, keep in mind that the letter has to cover the rods but not go past them (our letters are 5 inches tall). Having a bold and simple font was a personal choice that we recommend.

Because we wanted to streamline our process, we decided to have a built in diffuser in our letters. To defuse our LED strips we found that 0.6 mm of filament (2 layers at 0.3 mm layer height) perfectly defuses the LED strips when they are about 1 inch away.

We extruded each letter 1 inch, shelled each one with a wall thickness of 0.1 inch, then extruded the sketch again 0.6 mm to create a hollow body (Image 1).

Next, we projected the back wall (the thick one) and designed a framework such that the LED can be fixed to it and put in easily; this also reduced the amount of support material needed.

In our design, we have overhangs that are long (for example, the top and bottom parts of the B); while it is easier to design, it makes removing supports during post processing much harder, something we wish we changed.

Lastly, we made sure to put fillets on all external edges to prevent sharp edges and points. This provided a cleaner and cohesive look overall.

When printing, we made sure that our letters were flat on the build plate with the diffuser side down. We made sure by looking at layer one in sliced view on PrusaSlicer. If the letters were not flat, they would end up like the D, meaning that parts have an incorrect number of layers.

Additionally, we used organic supports with a 0.25 mm top and bottom contact Z distance.

• Also we were extra careful while removing supports because the diffuser is thin and can break easily.

Because we have a 24" by 12" laser cutter, we decided that we should split each board in half, so 24" by 6", and join them to make our board a total of 48" by 6".

• Note our boards were not actually 24" by 12" but often closer to 23.8" by 11.9".

Next, we designed the rod holders and put them in all 4 corners (see image for our measurements). These hold our two rods that create a parallel circuit with our letters (top rod positive, bottom rod negative).

Note we didn't want to screw the boards directly on the wall and thus didn't design screw holes on our boards. For our mounting mechanism refer to Step 8.

We designed the entire board in Fusion 360 and exported the sketch as a SVG file that we opened in Adobe Illustrator so that we could send it to our laser cutter.

Once we laser cut all of the boards and the rod holders, we prepared a place to glue to the boards (using butcher paper) and used a toothpick to apply the acrylic cement onto the rod holders and put them into their slots.

We glued them with the rods in so the rod holders would be upright and align with the others.

Also we placed weights on the rod holders to keep them in place when the glue expands.

We did not glue the two halves together because we wanted to have the option to take it apart for transportation.

Next, we designed hooks that can be used to place the letter on the rod. We decided that instead of building it into the letter itself, we would attach hooks later on. This would allow us to replace the hooks if they break without having to reprint an entire letter.

Our hooks were printed on a Formlabs Form 3 SLA printer in Tough 1500. We had initially tried to use a FDM printer with PLA but the hooks would frequently break. The Tough 1500 allowed us to have a much thinner part that was still very strong.

We designed the hook to have minimal tolerance so that our letters would not shift accidently. We also created holes in the hooks so we could wrap our positive exposed lead and ensure a reliable connection with the positive rod. Finally, to make the hook stronger we made it slightly thicker and used fillets to increase the surface area around corners.

The next step for us was to solder the LEDs and put them in the letters (each letter took us almost 30 minutes). To do this, we first cut straight LED strips that followed the general outline/shape of the letter. For especially sharp curves, we cut the LED strips into multiple segments and soldered those together to form the curve.

Our LEDs had resin on top to protect the circuit, which we had to remove using flush cutters/x-acto knives in order to access the copper pads.

To connect each of the LED strips, we used solid-core jumper wire. We found it important to use wire so that the joints could bend rather than directly bridging the pads together with solder. If the joints were not flexible, the copper pads would often just rip off when we were fitting the LED strips in the letters.

After the LED strips were soldered, the last step was to add the two leads for positive and negative, as seen on the letter D. For this, we took two long pieces of solid core wire (4 to 6 inches long) and stripped 1/2 to 2/3 of each wire. We then soldered one wire to the positive terminal and one to the negative terminal (we will come back to these leads in a few steps).

Once all the soldering was complete, we applied double-sided tape onto the back of the LEDs in the places where it would contact the back of the letter. While our LEDs did have a backing with adhesive, it was simply not enough to hold the LEDs in place which is why we had to use double sided tape.

After all the taping was done, we carefully slid the LED strips into the letters and stuck them onto the back, all the while ensuring that the copper pads did not rip. This step is where we were most prone to rip off our copper pads, so we made sure to take extra precautions.

• If our letters didn't work on the rod, the most common reason was because of a damaged copper pad.

Our last step was to attach the SLA-printed hooks onto the top of our letters using double-sided tape. We then took the positive leads that we had soldered and wrapped it around the holes in the hooks. For the negative lead, we ran it down to the bottom and taped the exposed wire down. This would provide a connection to the positive and negative rods powering the letter on.

• We tried to put at least two hooks on each letter (this provided more stability to the letter when put on the board), but for certain letters like the "A," it was not possible.
• A bad connection of the leads to the rods was also why our letters would not work.
• Sometimes, our leads/any of the other wires would touch another wire, which would cause a short circuit. If one of these short-circuited letters was put on a board, it would cause the whole row of letters to go out. Diagnosing this problem was not a huge issue as it was pretty easy to identify which letter was causing the row of letters to go out.

We decided that we would want to move and show off our sign often and thus didn't want to mount our board to the wall directly. This led us to create a mount that clamped snugly around our board. We screwed the mount onto the wall and then placed the board on them and secured them in place.

• We made our mounting mechanism extra thick because our boards are about 6 pounds each).
• Our original idea was to slide the board in, but because the boards are quite heavy and long, we decided that would be too inconvenient. Therefore, we opted for a design that would allow us to place the board onto the mount and then clamp it using a piece that slides in from the top.

We made the mounts with indents so the screws fit flush, as well as a larger indent for socket head attachments.

Finally we soldered the USB pigtails to the rods, plugged the USB to power, and turned it on!

• Positive (white) lead to the top rod, negative (black) lead to the bottom rod
• It seemed dimmer than usual, and it turns out that rods began to oxidize. To combat this, we sanded the rods down with high-grit sandpaper. We started off with 400 grit and moved our way up to 1600 grit.

Thank you so much for taking the time to read our Instructable and we would hear back from you if you build our project or have any feedback!