Would cabinets made using a custom extrusion technique be good enough (and worth the cost) for creators of prototype electronic products?
Below we see two different views of a real-world cabinet created using this concept. Since the die for the extrusion would cost more than I care to spend at the moment, I decided to see what I could do with off-the-shelf 3/4" x 3/4" x 1/8" right-angle aluminum extrusions. The cabinet pictured is 10" x 10" and 3" deep. (The power supply is a little overkill to minimize conductive noise issues for a sensor and the horrid ground loop. This is a prototype. I don't like spending inordinate amounts of time chasing noise issues, ground loops, and my stupidity.)
In the case of this example, everything is screwed together, which involves way too much work drilling and tapping. Of course, you can still do this with my proposed custom extrusions, but I tend to think glue looks like a better alternative. Having said this, I do struggle with things that cannot be easily undone (cyanoacrylate does come off with acetone, but unpredictably).
The way this works
The way I envisage this working is that I would have a die created to fabricate my special extrusions. When other people want custom cabinets made, they would send me the CNC files associated with the sub-panels for their cabinets (more about this below). I would take the sub-panel designs from multiple people and combine them into one big panel file to send to the folks with the industrial CNC laser cutter. By combining multiple sub-panels into one big panel in this way, the cost of laser-cutting the sub-panels will be reduced dramatically. Finally, I would ship the sub-panels along with four appropriately sized extrusions to each of the people who had ordered a cabinet.
What needs to be done
A die needs to be made for the extrusion. A website needs to be established for taking orders. And, most important, the customers need to be willing and able to supply drawings of the panels with the cutouts they want in DXF format files.
I'm thinking that the website could provide templates in DXF format for front and back panels that show the corner details. In this case, there could be a range of panels for standard-size boxes from smallest to largest. Cutouts for common connectors like DB-9 and DB-25, USB, and Ethernet could also be provided in DXF format. However, the biggest problem for making these cabinets is modeling the printed circuit board where these connectors are placed accurately so that the holes in the cabinet will line up. I do not see an easy solution that is also low-cost to the end user. We have the same issue with PCBs. Until Cadsoft's Eagle came along, there really was no good low-cost PCB tool available.
AutoCAD and SolidWorks have powerful features that make doing this easy, but also have a steep learning curve to get to the point of it being "easy." They are also expensive if you are not going to school. DesignSpark Mechanical looks like a possible alternative, but I have not used it myself. SketchUp ends up have a learning curve to make it useable, as do other open-source alternatives.
In the end, the CNC laser house needs DXF files that have all the sides panelized to enable a service like this to be at the cost level now available for prototype two- and four-layer PCBs.
A 12" x 7" x 4" LMB or Hammond U-shaped 1411 type Al box from DigiKey costs $27.30 plus shipping. Circuit Specialists offers a better-looking enclosure 11.9" x 7.5" x 2.9" for $17.95 plus shipping.
I got a quick quote from Protocase for three 3" x 11" x 11" U-type 20-gauge steel cases with 10 cutouts with black powder coat, no labels. The total was $616.99, which equates to around $200 each.
As I mentioned earlier, using my approach, a 3" x 5" x 7" deep cabinet would cost around $50. I estimate that a 10" x 10" x 3" cabinet would cost no more than $75.
So, here's the question
The basic question I have is: Would cabinets made with my custom extrusions be good enough and worth the cost for most prototype electronics builders? Also, would they be willing to wait one, two, or three weeks to take delivery of such a cabinet?
I am currently working on determining the cost of graining and anodizing the aluminum in batches to see how much this will add to the price. I am also trying to find a service that uses inkjet printers for creating text annotations and graphics on the cabinets. I know that this technique is currently being used by some PCB houses for their silkscreen legends, and I think this would enable an incredible flexibility in labeling, perhaps even coloring the entire cabinet.
Max here again, so there you have it. I think Charles has something here. I know that many of my own hobby projects would benefit from having a more professional-looking cabinet. And if you are a company creating a real-world prototype, having a professional-looking cabinet can be really important when it comes to presenting things to potential customers.
So, what do you think? Is this idea worth pursuing further? Should Charles go it alone, or would a Kickstarter project offer a good option? Please tell us what you think by posting comments below. Also, if you wish, you can contact Charles directly at firstname.lastname@example.org.