Drafting

Started: 2005-03-04 19:49:58

Submitted: 2005-03-04 19:52:04

Visibility: World-readable

The very first thing I learned in intro to engineering, long long ago, was some rudimentary drafting and drawing techniques. I thought it was fun, but I honestly thought I'd never actually use it.

I was wrong.

The latest project I'm involved in, based on our classic XY MDS (I take no responsibility for the colors on the site) requires me to locate the exact center of rotation of a platen and align it with the first nozzle of an ink jet print head. I can make the print head jet on command, so I can spin the platen under the print head and draw a circle, and jog in the X and Y directions to produce lines. Then I pick three points on the edge of the circle, draw a triangle, draw perpendicular bisectors of each edge (going even further back to high school geometry), and the lines will intersect at the exact center of the platen. I can draw parallel lines to my X and Y axis lines through the center point and measure the distance, then add those distances to the actual position I've commanded the platen to move to and calculate the position I should command to move the platen's center of rotation under the first nozzle. From there, I can move the platen anywhere I want and always know exactly where it is.