I can’t find solid information on this, but I assume that’s because it was designed for international standards. The mini headphone jack, which became popular later and is probably what you have now, is exactly 3.5mm (0.137795″). The original standard plug was an American design and the specifications call for a diameter of 1/4″ (6.35mm) on the barrel of the plug. Let’s take a look at headphone plugs to illustrate the complexity of this problem. Start by asking yourself where the part was made, and more specifically where it was designed. A part originating outside of the United States is probably metric, but what if it was designed by an American company and simply manufactured overseas? Alternatively, what if it was designed overseas, but with the purpose of interfacing with an American product? As when you’re designing a part from scratch, you should start with a rough shape and add features to make it more detailed. I use a basic workflow of five steps when reverse engineering a part. When, in reality your calipers were actually rounding up 0.19685″, which is exactly 5mm. If you take a measurement with your calipers and it comes out to 0.197″, you might assume it’s due to manufacturing and guess it to be 0.200″. When making inferences, you’ll also need to take into account whether the designer was working with metric units or standard units. Of course, the caveats here are measurements that either the designer didn’t explicitly specify (like the hypotenuse length of a triangle), or when the designer has to use a specific measurement to interface with another part or has a similar design constraint (like with an injection molded part, where you need a draft angle of 1 or 2 degrees). Angles are usually even divisions of 90 degrees-almost always something like 15°, 45°, or 60°. Lengths, diameters, and radii are usually round numbers in the design phase. You can probably infer that the person who designed intended it to be 4.00″, and that the 0.01″ difference was probably a result of manufacturing tolerances, or a slight error in measurement.Īs humans, we like to use nice even numbers when we design parts. For instance, if you measured a part like the image above, it might come out to 3.99″ instead of 4.00″. It’s all about making logical deductions from your measurements, based on the fact that the original part was designed by another human. This is the most important skill you need to develop for successful reverse engineering. It’s why you can look at a glass and say “yup, that’s about half full.” In regards to reverse engineering, it’s why you can look at the picture above and deduce that X is probably 2″ and Y is probably 1″. This is why you can look at an analog clock without numbers, and still guess the time with pretty good accuracy. Conversely, however, the human brain is very good at two things: making relative judgments, and making inferences. So, you need a way to get accurate measurements for reference features. “About 5 inches?” is the best most of us are capable of. Why are calipers the only measurement tool you need? Well, the human brain is very bad at estimating lengths with any kind of accuracy. Very precise models can cost hundreds of dollars, but basic digital calipers can be found for well under $30-and that’s probably all you need. But, for the parts most hobbyists want to make, all you’ll need is a set of digital calipers. We were reverse engineering parts with features that were too small to be seen by the human eye, so we had some fancy equipment like high-magnification optical comparators. The goal was to reproduce products that were indistinguishable from the original, and because they were used for things like trauma reconstruction, it was critical that I got it right. That meant that my entire job was reverse engineering complex precision-made devices as accurately as possible. Years ago, I worked for a medical device company where the business model was to duplicate out-of-patent medical products. In this article, I’m going to teach you how to reverse engineer and model those parts. But, what about the more complicated parts you’re likely to come across? That’s fairly straightforward if the part has simple geometry made up of a primitive solid or two. Of course, to do that you need to be able to make an accurate 3D model of the replacement part. Want some proof? Just take a look at what people made for our Repairs You Can Print contest. The ability to print replacement parts when something breaks is often one of the top selling points of 3D printing. If you’re interested in 3D printing or CNC milling - or really any kind of fabrication - then duplicating or interfacing with an existing part is probably on your to-do list.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |