Measuring tools are the most important tools to learn. All sorts of measuring techniques are what can differentiate between a poor designed part/assembly or poorly manufactured part/assembly from a good one. Measurements are the backbone behind good design. CAD is often used as a way of portraying real life objects digitally, so one may produce them again. We use traditional measuring instruments (rulers, tape measures) as well as precision instruments, the main one being the caliper.
We use (almost) exclusively the imperial system, so all things can be kept in inches
In the backbone measuring tool, there are smaller rulers and larger yardsticks for longer distances. Rulers are not the most accurate and when using a different ruler for the same measurement they're not very precise. Rulers and yardsticks are great as straight edges after using a protractor or drawing to figure out the angle the line must be drawn at.
There are two types of square measuring tools we use, framing squares and speed squares. Both are used to get straight 90 degree drawn lines. It's always good practice use one of these when making straight 90 degree lines because they're really accurate with the angles and are typically precise even when using a different square.
A measuring tape is great for measuring and marking large distances. They are flexible rulers that can lock. However, they aren't the most accurate nor precise when switching between tape measures.
Dial Calipers are precise and accurate measuring tools that can measure down to 0.01 inches. See the video to the left on how and when to use them. There are digital and mechanical calipers. Calipers are not good for large measurements. Calipers allow you to measure the inside and outside dimensions of an object with as much as 1/1000 of an inch accuracy! The caliper is relatively easy to use, and after reading this short article http://www.chicagobrand.com/help/dialcaliper.html you should have it about down! Try it on your phone, or a key on our keyboard, or measure the diameter of a pencil to try it out. (Remember: start at 0, use the big wheel to move it to size, read the leg of the caliper, and then the dial, and add).
This is a micrometer, a very precise and accurate measuring tool that is precise enough to measure down to 0.01mm. We rarely need to use this tool unless we're checking a measurement on a part when using the lathe.