I have had a few ask what the process is for the designs presented in the 52 in 52 project. Well, you asked for it, so here it is. I will keep this very brief so as not to bore anyone with details that are irrelevant. If you need more, email me and I’ll share what I can. The process is decidedly abbreviated in order to facilitate the pace of development within the time available outside completing customer work. This does not mean I short cut or bypass good design practice, it just means I go at this with a very lean process, where any and all work that can be set aside, well, is.
First and foremost, every product starts in 3D CAD. I use Rhino 4.0 with several apps added in for rendering and other functions, but the core program is where I live. Every design goes through a fairly quick progression of design iterations. Often the end result is an order of magnitude from the original thought, other times the iterations are primarily in detailing to make the design real. I may not draw every single component in precise detail. I have stored blocks for drivers, most LEDs, reflectors, switches, connectors, etc… Some are crude volume blocks with little or no detail to simplify the process and to establish the space around the part necessary. Other components, like LED arrays, might be more completely detailed and tightly dimensioned, as these tend to land in places where alignment tolerances are tight.
From the raw drawing files, I extract the dimensions I need to make the parts within the design itself. If the parts is going to be produced in plastic from prototype equipment, I generally won’t bother dimensioning them, as the machine does not require it.
All designs are developed in 3D CAD and dimensioned to aide in machining and fabrication.
With the drawing file completed, I often explode sections and assemblies where the order of parts is not obvious from a section drawing. Even though I design the products, the process of building the finished piece often occurs over a few days, or evolves as changes are made to improve details. These exploded views help me see and stay focused on the original intent. If something changes, I will update the drawing and recreate the exploded view.
Exploded views are handy reminders and assembly aides
With all of this rough engineering complete, the fitment between parts set, and the final configuration realized in virtual space, I will create a rendering for my own use. This often results in another series of evolutionary steps, exploring color combinations, or adjusting dimensioning, as the rendering reveals design inclusions that are not always apparent in the raw drawing and engineering phase.
The rendering phase reveals surface and aesthetic appearance issues not obvious in the engineering phase.
Once this is completed, it’s finally time to invest in materials to create the finished end product. I rarely waste materials in the production phase, unless I have a case of brain fade somewhere or a machine eats a part during cutting and or fabrication steps.
One final mock-up verifies fitment prior to finishing
With the finished parts in their roughed out state, I test the assembly of the major components. This is part of the step by step production process, as well as the last step before committing time to finishing everything for final assembly. In the case of designs that have questionable thermal or optical properties, I might assemble all of the working components and test the products performance at this stage, before finding out I have a problem after all the finishing is complete.
During the various phases of production, I do test the LED, driver, power supply, and optic in some form of mock-up state, usually involving gaffer tape and scraps of metal and plastic. I’m mostly looking for how the light output is going to look, where glare might rear its ugly head, or other unattractive performance issues that require correction as things progress. In some cases, I might mock up a rough version of the thermally involved components and do a test of assumptions. This is usually accomplished in the design phase in order to establish the materials to be used, or surface area, or other factors involved. In many designs this is redundant, as the surface area is larger than necessary. Once the core light generating and supporting hardware components are tested, I put them in a bin for later assembly into the finished product.
With finishing complete, all of the final parts and internal components tested and set aside earlier are brought together. At this point, everything comes together as a final product, wired and ready to go. Once complete, every light is plugged in, wired to a thermocouple, and left to operate for at least 8 hours. I check temperatures every hour or so, and check light output a couple of times along the way. If all checks out, I will often run the fixture for an additional couple of days and check light output against the first reading, just to see if things are acting as expected. There are occasions when an LED is not seated properly, resulting in a good initial test, but a rapid failure as the heat destroys the device inside. This will usually show up in the first 16 to 24 hours of operation, as long as the rest of the product is functioning well.
Designing products around LEDs and solid-state components is really not that difficult. Once you get the hang of the basics, the process is similar to any other product design. My largest failure point has nothing to do with solid-state, and has plagued me for twenty years in designing portable fixtures – that is balance. I don’t like big fat base-plates and stands, so tend to suffer issues of products that are a little unstable at times. Of all the aspects of design that cause me to engage in rework, this is the one that bites me more often than any other. While I’ve had a few LED fixtures require that I tune the current back to avoid over-heating, this is rare. Another area I screw up is designing components so quickly I miss that assembly is impossible. This usually involves a part that must be installed before another, that cannot be done in the necessary sequence. Nothing improves vision of such issues as much as actually making things directly. Things hide in CAD programs that will jump out and bite whoever ends up making the final product.
So, that’s the underlying process in brief. In prior entries, I have shown videos of a couple of the processes involved, and will do so in other areas again soon.
Oh yes, you are looking at Design 20, which will be finished in a day or so. Stay tuned!