A Note to Newbies
Hi
I'm Professor CB and I just wanted to say to those of you who are new to
precision measuring that there are a few things you should know and learn
right off the bat, particularly in regards to using calipers. By developing
correct procedures from the get-go your measurements will be much more
accurate and the projects that you work on will go together better like they
were designed to. That's the whole reason behind using these types of toolsWhen taking a measurement, close the jaws only lightly, with consistent pressure from one reading to the next to obtain accuracy. Try experimenting by pressing a bit harder and you'll see that it's possible to change the reading. This isn’t the material moving but the calipers are actually flexing. So don’t press too hard. With practice you should get the feel of what is proper. Practice for a while on a gage block or some other solid object until you get repeated readings.
For general measuring use the flat area of the jaws whenever possible. The ends of the jaws are beveled to get down into slots and grooves however using this beveled area more than necessary will wear the jaws down quickly. As they wear your accuracy will decrease proportionately. You can see any wear by putting the jaws together and holding them up against the light.
You’ve heard the saying “use the right tool for the right job”, well this is true for calipers too. The most common calipers have a measuring range from zero to six inches. These are the most useful because they can be handled easily. But know that it is difficult to take readings near the end of the range of these calipers without compromising accuracy. There are larger 8-inch and 12-inch (and even longer) available that might be more suitable. But don’t think to be clever and own just one larger caliper to cover all the basis because you’ll discover that the longer the caliper the more awkward they are in making small measurements. And speaking of using the right tool, use a caliper for what it is intended for. It’s not a screwdriver or a pry bar!
Brand new dial calipers may exhibit some roughness in movement. What you are probably feeling are the gear teeth traveling along the rack. This is normal but after some time, with use, they will smooth out somewhat. Wipe the beam before each use if you are working in a dirty environment to minimize getting dirt and chips into the rack teeth. Don’t oil them because that would only act as an adherent for dirt particles. Use air to blow away chips and grinding dust.
After a measurement it’s best to keep a caliper, or any other precision instrument for that matter, in the case that it came in. Laying it around the work area without any protection just increases the chance of something bad happening to it. Stay organized.