p2:3 – 3D printed RGB LED sign – modeling

modeling

We left off at the last post discussing the design of the sign. This post takes a dive into the various iterations I came up with, what I liked, and what I didn’t like. With each version I came up with, I tweaked things to improve the design.

version 1.0

With the design settled on (for now), it was time to jump to Fusion 360 and get started. Version 1.0 was pretty straight forward. I used the text tool and recreated my logo in 3D space. Extruded out the letters and outline, which would house them. My thought was that the letters would be pressure fit inside the outline housing.

the housing

It looked ok, but in designing it, I had neglected to account for the depth required to house the battery and ESP32. Up to this point, I also hadn’t considered the maximum build size of my Prusa MK3S. I wasn’t going to be able to print out each word in its entirety. I needed to split up the letters to print them and then assemble them together. Since I wasn’t that far along yet, I thought it would be best to simply scrap this model entirely and start anew. So that’s what I did.

version 2.0

With version 2.0, I thought about the depth required to house everything and how I would split up the letters. I would be able to print about a 7 inch portion each time, which is essentially two letters. For “mike,” I would need to split the print to “mi” and “ke” and assemble them.

housing depth and separation can be seen between the ‘i’ and the ‘k’

This was starting to look better, but I realized something at this point. The spacing of the letters was incorrect. For some reason, Fusion’s text tool gave the letters a different spacing than what is in my logo even though it’s the same font. Oh boy. I knew that Fusion had an canvas feature that would allow me to line things up perfectly. But I did not expect the text tool in Fusion to give the letters different spacing despite using the correct font. Alas, it was back to the drawing board.

version 3.0

Version 3.0 got a lot farther along than those before it. I was able to model all the lettering and their connections. I even started to plan out the screw holes where they would be attached to each other. I didn’t want to glue them, just in case I wanted to take it apart in the future. I even planned out the screw hooks that would be used to hang it on the wall.

version 3.0
screw hooks

In the screw hook picture above, you can also see the back of the housing. It would be mostly open to house the battery and ESP32. I could print a back plate that would fit right in to make it nice and tidy. Things were looking good. But after a night of sleep, I realized that this design used entirely too much material. Not only could I redesign it to save a significant amount of material, but I would also be saving a significant amount of print time. Win-win if you ask me. So, the next chance I got, I started from scratch again.

version 4.0

With version 4.0, I was feeling good. I had a clear vision in my mind and I had the thought that “this would be it!” Well, it wasn’t. Taking into consideration the ideas to redesign and save material, I made the outline of the letters simply the front facade, while the body was narrower to the outline of the letters themselves. This would save me material and print time. I also considered how I would join the words together and designed join posts that would be attached with M2 screws and nuts. I also designed screw posts that would allow me to attach the back plate to the rest of the body to make sure everything stayed inside.

a peek at the join posts between the O and the LLs
holes for the screw posts

In the picture of the screw posts above, you can see where I changed my design. In the top word, the screw posts are attached outside of the letters to the letter outline material. In the bottom word, the screw posts are within the letter body portion and would attach to an LED plate. I did this because I did not like the look of the body portions having cutouts. They would be visible from any side angle view and I didn’t think it was aesthetically pleasing.

After printing out the “all.” to see how my prototype actually looked in person, I realized the many shortfalls of my design. First, I realized my screw posts were pretty pointless. Putting the prototype together made me realize a pressure fit would be more than sufficient to keep everything together.

I also realized the join posts were entirely too small and very difficult to get to. They were also a bit too flimsy and had a chance of snapping with any decent amount of force. Considering it should be at least strong enough to support the weight of the sign freestanding on a table, they needed to be stronger. Similarly, the letter outlines were somewhat fragile as well. While forcing in one of the tighter fitting letters, I bent one of the letter outlines and separated it from the body. Luckily, it did not come off all the way, but it was enough for me to know I might need to strengthen that joint. Most likely, with some kind of webbing. I have to think on that.

Lastly, the biggest issue was realizing that the battery I had planned for this just wouldn’t fit within the letter body the way I had imagined it. There were a lot of flaws that needed to be fixed. Here’s my list.

  • Eliminate screw posts – don’t need them!
  • Find a place for the battery and USB power cable
  • Strengthen outline to letter joint (maybe?)
  • Strengthen word-to-word join points
  • Strengthen letter-to-letter join points
  • Improve wiring flow and pre-print holes to route them.
  • Find a spot and add mounting screw posts for ESP32

version 5.0

By far, the biggest problem I faced was finding the right place for the battery and the ESP32. THe power bank was too large to simply slide into one of the letters based on the new design to reduce material use. Even if I had expanded one of the letters to accommodate the battery, it would have added to the depth of the sign and increased the material use for all the letters because they needed to be equal length. What I decided was to fit the battery behind the “ll” in the “all”. It would mean the space between them would not be clear and open, but it’s such a small gap that I don’t think it would take away from the visual appeal of the sign. Not only that, but placing the battery flat against the back of the letters would further decrease the depth of the sign from front to bank, saving me even more material! This idea was a go and in Fusion, I designed a pocket where the battery could sit inside without falling out, even if left to free stand.

This first picture is a view of the “all” portion of the sign from behind. As you can see, there are no more screw posts for the back panel to screw into. Instead, everything has been designed to pressure fit within the outline of the letters. A pocket behind the “ll” can be seen where the material is indented. You can also notice two screw posts behind the “a”. This is where I decided to place the ESP32 controller. Both the battery and the ESP32 would sit on top of the back panel with their wiring being routed under the back panel and into a gap between it and the panel on which the LEDs would be mounted.

Notice the large, blocky structures on top of the “all” and between the “al” and the “l.”. These are my beefed up join supports. Instead of having join posts behind the outline of the letters, I decided to design them connected to the actual body of the sign. This would ensure optimal rigidity. It also allowed me to use screws from inside the openings to connect everything. Not only would it be easier to access for assembly, but it will be much stronger as well.

back view of “all” portion
back rotated view to see indented pocket for the battery and ESP32


I wanted this sign to be able to be freestanding on a tabletop or shelf. The prior versions did not add any type of material to even out the bottom in order to keep the sign vertically straight. In version 5, I added these feet that extend from the front to the back on which the sign will rest when freestanding. There are notices in two of the feet, which will serve as routing guides for the USB cable coming from the battery. Power will be sent from the battery, through the USB cable, and into the sign from a gap at the lower right of the ESP32.

view of the back with battery and ESP32 in place


Another note on the join supports are the built in screw holes. These are accessed from within the opening that will be occupied by the letters, which means that will be invisible once assembled. I also designed gaps (the rectangular opening in the image below) that served as wiring routes from one word to the next. Based on my design, the wiring would flow from the bottom to the top with power being daisy chained from one LED strip to the next and data being fed from three data pins to each LED strip, respectively.

screw holes for attaching to the “do” of “does” and rectangular hole for routing wires

You can also notice the bit of webbing behind the letter outline with the letter body. I gave it a shot to see how this would effect the structural integrity. But, after examining a test print, it didn’t seem to add any additional rigidity in the joint. So, I decided to leave them out for the rest of the words.

Another note, if you look closely at the battery opening and the cable routes in the feet, you’ll notice thin bars going across. These are sacrificial supports I added in order to eliminate the need for adding support structure in the slicer. These supports are spaced close enough that the printer’s bridging ability can easily manage. Once done, they can be snipped off with flush cutters. The great thing is that they take up a lot less material than actual support structures and in this situation, are more than sufficient to do the job. As I do more designs and printing, I am definitely trying to incorporate more features in my designs to reduce material and save print time. With that being said, the total print time of this “all.” was about 14 hours for all the parts 2 batches. Not exactly instant gratification, but I was more than satisfied with the result.

That’s basically it for the modeling of the sign. I think I was able to address all the flaws I noticed in version 4. I’m very happy with how version 5 looks and look forward to printing out the rest of the words, having them ready for LED wiring and assembly. Any questions and comments are welcome. In the next post for this project, I’ll be talking about the LEDs. I will need to test out the circuit I designed with the ESP32 and writing a program for all the desired features and animations. Lastly, I’ll need to figure out how to enable voice control via Google Assistant and write an Android app to control the sign. All this and more in the next update. Thanks for reading!

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