Let's take a break from the design process to talk about methods for applying front panel labels. Although there are many ways to label a panel, this guide will detail the two that have been working well for me given my limited set of hand fabrication tools (no 3D printer, drill press, laser cutter, or milling machine).
Each method attaches the labels through a series of layers that are drilled or machined in a specific way. Let's start with the first technique, the Sandwich.
The sandwich approach consists of three layers, the enclosure base, an ink-jet printed layer, and a clear covering that protects the printed layer from wear and tear. This is the more rugged of the two techniques and is the one that takes longer to prepare.
The enclosure can be almost anything from aluminum or steel to ABS plastic or acrylic. It can be 3D printed or assembled from laser-cut plywood. Your project will dictate the selection of the enclosure material. For the UFO miniature controller, the enclosure material selected was ABS plastic, sized to fit the layout of the front panel (Jameco #18893). The label graphic layer is ink-jet printed on a sheet of high quality photographic paper. A sheet of 1/16-inch transparent acrylic or polycarbonate plastic is used for the clear layer.
Most components, when mounted, will require holes through all three layers. Components with index pins such as potentiometers and toggle switches will require an additional hole in only the enclosure layer. It's not recommended that you clip off or bend the index pin to avoid drilling a hole for it; the index pin will keep the component from changing orientation. Without the index pin, the shaft nut would need to be overtightened to prevent spinning, causing the label graphic and clear layers to warp and distort.
Components that are not natively designed for panel mounting such as an LED with wire leads can be mounted by using fabrication accessories such as a bezel. A bezel will help to disguise the mounting hole and will improve the looks of the LED.
The second labeling method consists of just two layers: the enclosure and a vinyl sticker with the printed label graphics. The enclosure layer is machined exactly like the sandwich method. A pre-printed sticker is then aligned with the holes and carefully applied. Status lights can either be mounted with a bezel or placed just under the sticker with a dot of hot glue or blue tack. If the area of the sticker above the LED is a lighter color, the LED's glow will usually shine through.
Since the vinyl sticker layer is soft, it's essential that component index pin holes be used so that shaft mounting nuts will not have to be overtightened to prevent spinning. The uncut sticker layer above the index pin hole will cover and disguise the hole.
This method is easier to align and much faster to prepare than the sandwich method and works well for projects that won't see continuous use. It isn't as glamourous or shiny as the other method due to slight flaws that result from the vinyl printing and coating process, but the colors are vibrant.
Commercial vinyl stickers come in many varieties and finishes. It's recommended that you look for stickers with a clear outer protective layer designed to minimize UV and physical abrasion damage. Tell your sticker vendor that dimensional accuracy is important to you and ask them to minimize the border size to avoid trimming the graphic content during printing. StickerMule, who has an affordable 10 unit minimum order quantity, was the vinyl sticker printing vendor selected for the controller project.
We will step through the Sandwich panel labeling process next. Many of the techniques for preparing the enclosure layer will apply to the Sticker method, which we will cover in its own chapter.