Saturday, July 19, 2014
Audio System Overhaul: DSP Enclosure Arrives
A few weeks ago I sent out four RFQs for manufacturing my DSP enclosure assembly but only two of those responded with quotes. The first company to respond (in less than 24 hours) was Rapid Sheet Metal located in New Hampshire. I'll credit this company with providing valuable online resources that helped me prepare the design for manufacturing. That sounds like an easy thing to do but it's not as simple as clicking "save" and throwing the data over the wall. Just as I've said that it's quite possible to construct designs in Solidworks that are impractical or impossible to manufacture, the reality is every manufacturer has a finite set of standard tooling. Go outside of the design criteria allowed by those tools (bend radii, etc.) and costs skyrocket.
I watched one of Rapid's videos that pointed out various potential “gotchas” and bad design techniques that they see on a regular basis and are forced to correct, possibly with a lengthy back-and-forth discussion with the customer. Although my design was extremely simple I did wind up making some tweaks to it based on what I learned. For that reason alone I really wanted to give them the contract, and I honestly thought that most of the quotes would be in the ballpark. Unfortunately, when I received Rapid's quote I began to have flashbacks to my experience with my BMW pulley design. They admitted their cost had to do with the fact that I was producing in such low volume (which was stating the obvious), but the reality is companies that charge more than others for the same job invariably have higher overhead or margins. I ultimately concluded that their business was perhaps better suited to production work that I might do in the future.
The next response arrived from Prototek Manufacturing, also located in New Hampshire, with a price of about 60% of Rapid's so I quickly awarded the contract to them. Manufacturing cost is typically front loaded, meaning most of the labor is in design validation and programming of the machines so I wasn't surprised to learn that Prototek's quote for three assemblies was essentially the same as for a single assembly. Given this financial reality and my desire to have a backup or two “just in case” I authorized the production of three assemblies. That was roughly two weeks ago. The assemblies arrived today and they look great. Some preliminary fitting of the PCBs and the cover screws has convinced me of the power of CAD/CAM– everything fits together beautifully. I could not have done a better job myself.
Although I think the unifinished components are attractive enough to install as is, the 1018 mild steel I specified to reduce cost will rust if left unfinished so I plan to degrease, prime, and paint the parts. When that's done I'll install the PCBs, build up the harnesses, and then thoroughly test everything on the bench so I can be assured of a successful integration process in the vehicle.