Acrylic LED Sign Shim

History

The stock I use for etching my acrylic LED signs is obtained from Amazon, as are the bases I use with them. The sign stock is 2mm acrylic, while the LED Lamp Base seems to be designed to hold ~4.5mm acrylic.

There are three different styles of stock I use; heart circle and square. When the acrylic panel is inserted into the base, it doesn’t stand upright. It either leans forward or backward by several degrees, causing the light to not distribute evenly through the acrylic and the overall appearance to be dim.

Designing a Solution

The first thought I had was to make a shim that would fit between the acrylic and the slot to fill in the space. At first I tried things I already had laying around, like a popsicle stick (it fell down inside).

But the slot in the base is not only relatively deep (16mm), but there are these three little nubs on either side of the slot that are designed to shim the slot for 4.5mm acrylic. Of course, this doesn’t help if the material you’re using is less than half the width the slot is designed for.

Version 1.0

I decided to design a shim. A simple 2D shim that would stand in the slot and take up the additional space. A few years ago I was learning FreeCAD, but at the time in was in Beta (V0.19). Since then it has reached V1.0 and so much has changed. It’s got a bit of a learning curve, so I decided to see if I could just design the shim within Bambu Studio (the slicer software).

It turns out, you can create primitives within the slicer and modify their parameters. Being that the shim is really just a 2D object in a sense, it seemed reasonable to assume I could easily create the shim within this software. I created two cubes and then resized them to be the dimensions I wanted and then merged them together to create a single part. In this case the Z-Axis is just the thickness of the shim.

The first version was too tall and the tab was too high, causing it to stick up out of the slot too much. Also, if you look at the second photo, you can see that the merge wasn’t perfect. It still looks like two pieces fused together, which is not how it should look.

I revised it and printed the revised version, which was the right dimensions. The photos here show the updated version. I was so confident that I had solved the issue that I printed a whole plate of these shims (third photo).

This is what the shim looks like installed in the slot of the LED Base.

However there was a small problem. Those nubs I mentioned earlier don’t seem to go all the way down inside the slot. The problem is that the bottom of the shim (and the acrylic, if long enough) can still move around at the bottom of the slot. So, even though the sign is more upright, it is still unstable and still moves some. You can see more details of the slop in the video below.

Version 2.0

This time I decided to make a 3D shim. More of a sleeve or adapter, than a shim. It would essentially match the size of the acrylic to the size of the slot, all the way down. Since I was still doing this inside Bambu Studio, this involved making a lot more primitives to join together.

The results were better than I expected. Since the shim is symmetrical, it wasn’t difficult cloning the parts for the opposite sides and merging everything together. The part printed flawlessly.

This is what the shim looks like installed in the slot of the LED Base.

And the final result after the sign has been installed.

This final version is so perfect, you can even hold the sign upside-down!!!

Using the 3D Shim

To install the shim, place it over the tab at the base of the acrylic sign. There is virtually no margin for error when using the square stock (the round and heart-shaped stock has more room), so you have to make sure it is inserted straight into the shim. Once the sign is in the shim, push the entire shim into the slot in the base, again making sure that everything is square.

To remove the current sign and replace it with another, pull the acrylic straight up out of the shim while holding the edge of the shim in place with your fingertip. See the video below for the instructions. You can also watch the full video at the link in the Resources section.

[VIDEO – installation video]

Final Thoughts

This projects solves the issue of using the LED Bases from Amazon with the popular Acrylic Sign Stock from there as well.

Resources

Maker World Model Page

Short Circuits: Acrylic LED Sign Shim – Video

Buffalo Bills Acrylic LED Sign – Project

NASCAR Acrylic LED Sign – Project

Discuss this project on Savage///Chats

Acrylic LED Sign Shim by Chris Savage is licensed under CC BY 4.0