Origins? You Don’t Need No Stinkin’ Origins.

originswWhen I worked in AutoCAD, I guess I got used to working with the UCS and WCS and whatever. I learned how to manipulate stuff in 3D, but you had to do it in your head, thinking in 3D coordinates. That’s the kind of skill you have to develop, but it ain’t easy. When I moved to SolidWorks, I realized that all of that energy was wasted. You don’t draw stuff in 3D coordinates in SolidWorks. You don’t even draw stuff in 2D coordinates in SW. Command line coordinate input? Remember being really fast at that on the keyboard? How much value do you place on that skill today? Zero.

Here’s the thing, I think this is mainly a philosophical question, not a technical question. It’s got about as much likelihood of having a single correct answer that everyone can agree on as say religion, politics, or smart part numbers. The thing is that it really doesn’t matter. Everything in 3D is relative.

If you were around in the early days of SolidWorks, you couldn’t use the software without getting the idea that X, Y and Z didn’t matter at all to the people who wrote it. These were in the days before the triad that shows X, Y and Z , and when you couldn’t find a single function that referenced the letters X, Y or Z except maybe the Measure command. On the standard templates the standard planes were named Plane 1, Plane 2 and Plane 3. I think the people who started the software wanted to get away from thinking about parts as being relative to a coordinate system, and just thinking about the part geometry itself. SW was trying to move people away from the rigid Pro/E way of doing things where you always had a datum plane to something a little more freewheeling where you just worked from model faces and when necessary planes were relative to model faces rather than relative to other planes.

I think you can still find some residual “who cares” attitude about the coordinate system in SolidWorks. There are still pockets of resistance against making SW exactly like AutoCAD, and this is one of them. I for one, don’t care at all about the coordinate system. It’s completely arbitrary. At one point I renamed my standard planes in my templates as Larry, Moe and Curly, just to show exactly how little it mattered. Some people are still offended that the triad in the lower left doesn’t show up at the actual part or assembly origin.

There are other CAD systems where origins seem to count for even less than in SolidWorks, or where there is no such concept as an “origin”. I’ve worked with them enough to know that I’m a little uncomfortable with that extreme.

That said, it is nice to have a fixed point of reference, but that’s all it is. Reference. Ever talk to those folks who believe that all of the parts of a car should be designed in the coordinate system of the car, not in a local coordinate system? Ever see them place a bolt holding up the gas tank based on its orientation with respect to the center of the end of the crankshaft?

I was reading the SW forum tonight, and saw someone, maybe a machinist going off about the non-existent world standard where Z is straight up. Sounds like the non-existent world standard they had when the earth was flat. (here’s a poll on the SW forum where even the machinists can’t agree about which way is up). Wake up. It doesn’t matter to people who design parts. Plus, if we had to design in the coordinate system preference of whatever process would be used to manufacture parts, it would be another collossal waste of time. We don’t have a radial coordinate system for lathe parts. We don’t have a movable coordinate system for bent parts. We don’t have a Z is the smallest dimension coordinate system for additive manufacturing systems. We don’t have a direction of flow coordinate system for injection molding. Plus, part designers determining the fixture orientation for machined parts just sounds like a bad idea.

Leave a Reply

%d bloggers like this: