RenMan68
Member
Getting back to the point I made which started this whole thread... does anybody know how the Model 3 factory is laid out? (been on a tour?) That is, how many lines are there through the place? Is it just one or several? If the factory as a whole outputs a car every 3 minutes, let's say, there are basically two ways to do it: either the entire assembly process is broken into 3-minute tasks and the entire process is serial (that is, car #1 goes into stage 1, when it's done 3 minutes later it goes to stage 2 while car #2 goes to stage 1, etc.) or there are parallel lines which can take more time per car at a given stage but more than 1 car is being made at a time. For example, if it takes 3 minutes to put a single door on the car, you could have a stage 23 for left front door installation, stage 24 for left rear door installation, stage 25 for right front door, and stage 26 for right rear door. Or you could have a car go to one of four 'door installation' pods where it takes 12 minutes to put all the doors on a given car but you have four of those going on at the same time. Either way you get a car made every 3 minutes. The point of this long post is that if it takes more than 3 minutes to paint a car (which I still believe it does- from the time it enters as a bare metal object to the point of being ready for the next step, like installing the seats, has to be more. For example, BMW states that it takes 12 HOURS to paint one of their cars. reference: Paint Shop | BMW US Factory ). Makes me think that there are multiple places in the Tesla factory where cars are painted. I also heard from a VW plant worker through a friend of mine that the hoses and nozzles are purged in between EVERY car to avoid spitting, so changing color from one car to the next would not cause a delay. In the end, I don't think 'batch colors' even exist or, if they do, they're for reasons other than 'changing the paint color' in the ONE paint booth. As said above, the XKCD illustrates that reasons often aren't obvious. It's probably driven by an accounting issue or something like that.Painting the car on the move probably isn't as difficult as it initially sounds. The movement will be linear and slow. The robots are on a linear rail so they can match speed to the car.
Total guess since the only "robot" work I've done is building and running a 3D printer, but I'd say they programmed the robots sitting still, then added a linear motion along the rail to them after the paint movements were ironed out. I'm not sure if these expensive robots work on g-code, but it would be pretty trivial to add a linear motion along another axis to g-code designed for the rest of the motions.
Not trying to suggest anyone that commented doesn't know what they're talking about, but there's an amusing XKCD that illustrates that sometimes the reasons why task is or is not difficult isn't always obvious.