- Published: Monday, 10 August 2015
- Written by Jon Chandler
- Hits: 3227
I needed panels for my FAA project. The original plan was to use aluminum panels supplied by one of the FAA support groups, but that proved to be unreliable. At this stage of the project, the FAA was ordering in lots of ten, and the future of the project was uncertain. I never knew if an order for ten units might be the last-ever order, and there wasn't enough money in the job to buy in quantity, not knowing if extra parts would be used.
I looked at Front Panel Express. They will make small lots of custom-designed panels. I quickly drew up the panel I needed using their software, and found the price. One panel would cost a hundred bucks to make! Buying 10 at a time brought the price down to $80 each. Ouch. This is for an aluminum panel, powder-coated, engraved and back-filled with paint, so it's probably not an unreasonable price, but it wouldn't fly for my project. My contact at the FAA wanted a target price of $300 per unit. The heavy duty industrial switches cost nearly $100 by themselves and the other parts costs were not small since each unit has two circuit boards of about 150mm x 100mm. The Front Panel Express software is nice in that it shows you the cost of every operation; you can decide if that extra hole is worth the cost.
In this article, I'll share my exploration of using laser-cut acrylic panels as a cost effect alternative.
The prototype units had laser-cut acrylic panels. Laser cutting is relatively cheap, I can have it done locally and it's practical for small or large quantities. Plain acrylic wasn't a good choice, since I needed labels on the panel. My first thought was the plastic that's used for engraved name tags and door signs. You've seen it; often it's black, with white lettering. Engraving the black surface exposes the white core. Rowmark is one of the largest suppliers of this type of material.
Rowmark has a lot of interesting products. MetalGraph Plus looked like it might be ideal. It's available in several different metallic looks, the surface has a hard-coat finish for durability and 3mm thick material is available. I did some research and one of Rowmark's distributors is in Seattle, and they had a piece of the brushed nickel in stock.
I had a sample panel cut and engraved. Engraving the material exposes the black core. Very sharp and it has a nice feel to the touch. The panel was plenty rigid for my application. I showed it to my customer and he was enthused and importantly, he was open to the idea of an acrylic panel. Unfortunately, the feedback after showing it to some other people was that the glossy (almost mirror-like) surface was unacceptable for use in a control tower where the sun might reflect off of it. This photo shows a demo panel.
Most of Rowmark's materials have a glossy finish. Those that didn't weren't available in 3mm thickness. Blast. I called their technical support people and explained what I needed. "Look at ColorCast." Hmm. This material is a little different than most. The color layer is on the back of clear material. Instead of engraving from the front, you engrave from the back, leaving a hole in the color layer. Laser engraving leaves the surface sort of frosty, not optically clear. The engraved areas are painted in any desired color to make labels in any color desired. ColorCast is available in many colors, including almond which matches (many of) the FAA consoles and it's available in a matte finish.
The photo below shows a piece of gray ColorCast that's been engraved but not painted. The engraved areas look frosty.
This photo shows the back side of the gray material. This is the side that's engraved, with a mirror image. The back surface of the gray material is white. On the almond, it's black.
Painting the labels is simple. The non-engraved material is opaque, so the painting doesn't need to be precise; it's only necessary to fill the engraved areas and it's perfectly ok to slop over the non-engraved areas. This photo shows the back of a painted panel.
Here is the view of the front side of the panel.
And a picture of an assembled unit.
The ColorCast opens up a lot of possibilities. One option is using different colors of paint for the labels. Each label can be a different color to identify different functions, or in this case, to differentiate sections of the timer. Unfortunately for this application, the yellow paint on the almond panel does not provide adequate contract under all light conditions.
Other interesting options are using LEDs behind the engraved areas. That's my plan for the gray panel above. I'll let you know how that works out. Here's a poor quality picture of a little test panel I made; it's difficult to get good pictures of illuminated LEDs but it will give you the idea.
ColorCast does have some issues. The first is internal reflections. You'll notice in the pictures above that the panel color doesn't look consistent; there are light areas and dark areas. This is caused by reflections from light entering the cut edges. You can see this in the photo below, particularly large bright patches to the left of each opening. In this case, the switch bezels eliminate some of the effect, but it's still visible around the display openings and along the edges. I don't find it too objectionable but I was surprised the first time I saw it.
This material can be tricky to cut as well and it takes a skilled practitioner to do a good job at it. The material has minor variations in thickness as Rowmark warns, so the laser settings may need to be adjusted across the sheet of material. Internal reflections can also create problems when cutting; the laser light bouncing around inside the panel can produce internal stress fractures resulting in a mottled look or sparkly areas. Fortunately, Rowmark has good technicial support, and s skilled practioner won't have much trouble once the problems are understood. Expect some learning curve in cutting this material. The first batch I had cut was a nightmare. The latest (i.e., second) batch was perfect - 10 perfect panels with no wasted material.
So how does the cost compare to a metal panel? Ten painted engraved aluminum panels would cost $80 each. These panels cost $13 to cut and engrave and $5 in materials. I paint the panels myself, which took about 30 minutes for two coats of paint.
The important part here - the panels have been well accepted and the project will soon national approval. Here are a few pictures of installations in control towers.
The second picture shows an installational in progress, replacing an existing unit. The hole in the console needs to be enlarged slightly so the unit's not screwed down yet. The big box on the console is the unit it's replacing.
The final picture shows one of the first units, installed on an FAA-provided metal panel. Of note in this picture is the high-tech egg timer that was being used prior to this installation.