11:46 PM

CAD

Here's a little taste of what I do. I had a bit of free time today so I decided to show what I spend a good part of my days doing. Here I will be using Solid Works to model a bicycle stem. This would be one of the first steps that the engineers at a bicycle company would have to go through to make a certain part for a bike.

First, you need to know what you're going to be building. Usually engineers are given drawings with dimensions of what they're building. Sometimes they have a physical piece that they can take measurements from. In my case, I'm going to be building it after the Dura-Ace stem that I have.


The program needs every input to be specified. You need to specify which plane in a 3d space you want to use first.


Its like building out of legos, you have to take anything and simplify it to blocks and cylinders. Here I'm extruding the top part of the stem as a rectangle.


Like I said earlier, you have to specify everything. Here I'm creating a plane that's 75 degrees from the top piece of the stem to build the base on. I measured the angle from the Dura Ace stem. If I wanted to make the angle more aggressive I could easily make the angle steeper.


Here's the round base, the part that goes into the fork.


This part just joins them together and fills in the missing piece.


Time to make the clamp! Its already starting to look like a very crude stem!


Here I have to loft two surfaces to connect the stem with the clamp.


Here's the fun part, using the fillet tool to smooth out everything and make it look like the real deal!


Some more smoothing out.


Now to make it more realistic and less crude I'm adding the tapered cut on the bottom of the clamp. It really helps to have a good sense of space and a big imagination.


Makes it look dead on!


Now I just have to ad my own touch!


And finally, here's how it looks on a virtual bike that I've built. Pretty good huh?


Now engineers don't spend hours building these CAD models just for fun. These models are used to optimize and realize a design before it goes through the manufacturing process. This way, they can see potential problems, optimize sizes, weights, and geometries before ever having to go through the trouble to building one.

Here I've run the stem through a program to analyze the weak points of the structure under heavy loading. Here the weakest points are where the red parts are, as expected the thinner parts are in trouble along with the corners where all of the forces are concentrated.


Lastly, these drawings are used to communicate to a manufacturing machine of some sort like a CNC machine. Simplistically, it tells the machine where and how to cut a block of metal stock to turn it into this lovely stem.


I saw a commercial on TV awhile back that told kids to take more math and science classes because apparently we don't have enough engineers and scientists in this country. With this economy and the lack of jobs it has caused I'm glad that we're lacking in engineers! haha. but in any case, I hope this writeup brought some positive and fun light into engineering and maybe convince some young genius out there to be an engineer instead of something like... a local thug. And if you are a company looking to hire a CAD maniac shoot me an email!

Du