How to Use and Read a Dial Caliper

Welcome to my channel, Matt's Metalworking. Please don't forget to hit that LIKE button and SUBSCRIBE for future videos. My name is Matt and I produce metalworking relating videos which can include fabrication, machining, milling, turning, welding, tool tutorials, etc. In this video, I will be showing you how to use and read an imperial dial caliper. A caliper can take measurements in four different was using the outside jaws, inside jaws, depth probe, and using the step. A dial indicator basically takes place of the vernier scale, making the caliper quicker and easier to read, while requiring less skill or time. This isn’t as easy compared to a digital caliper, but there also isn’t any electronics or battery upkeep. Just like any precision measuring equipment, this should never be dropped, always kept clean and free of any foreign contaminants, and checked periodically to ensure it’s accuracy. First is the outside jaws which are used to measure the outside diameter, length, width, or thickness of an object. Next is the inside jaws used to measure the inside width of a slot, groove, or hole or the inside diameter of a bore. Here is the depth probe or rod using the measure a groove, slot, step, or hole. The beam or sometimes referred to as a bar is the frame of the caliper that is stationary and houses the depth probe. The measuring scale which determines the measurement, in this case, how many inches and tenth decimal place. A reference edge to determine where the measurement sits on the scale. The dial indicator which determines the hundredth and thousandth decimal places. The face can be rotated, in order to zero the dial. Here is the fine adjustment thumb wheel to achieve accuracy when setting up or adjusting the feel or drag when measuring an object. Then the thumb grip for quick or large adjustments. While it’s hard to see here, but here is the track which needs to be clean at all times as the dial indicator gear runs on this. Above the dial is a thumb screw lock to hold the caliper measurement in place. And then the step measurement surfaces used to measure steps, groves, or other differences in surface elevations. Always ensure the surface you are measuring is clean of any surface imperfections or dirt. Also, make sure the measuring points on the caliper is clean as this can affect the accuracy of our readings. Close the jaws and zero the dial face of need be. Now taking the first measurement using the outside jaws on the scrap piece of aluminum. Holding the piece between the jaws with mild pressure or drag so the part is movable, but not clamped between the jaws. Looking at the reference edge, as you can see if hasn’t passed the 1 inch mark, but is past the 0.500 thou mark. Taking a reading from the dial, the needle is at 79. Giving us a final measurement of 0.579 thou or thousandths of an inch. Now using the step measurement, push the step of the movable part of the caliper on the high part and then push down. Just to give you a view on the backside for a better understanding. Again the reference edge hasn’t passed a full inch yet but is past the 0.500 thou measurement line on the scale. Taking the reading from the dial, we have 19. The final measurement is 0.519 thou. Using the same machined edge with the depth probe this time to demonstrate the accuracy of the reading. We have the same reading as previously being 0.519. Using the depth probe again to measure inside the threaded hole. Unfortunately, the depth probe is thicker, therefore it will not fit into smaller diameter holes. Extend to give it plenty of length. Insert and then push the frame of the caliper down against the outside face of the object. Taking the reading, the reference edge still isn’t past the 1 inch mark yet on the scale but is past 0.900 thou. The reading on the dial is 63 giving use a final measurement of 0.963. And as you can see the depth of the probe comparing it to the part. And finally using the inside jaws to measure a hole or bore. For slots with a radius at the end or a bore, you may need to rock the jaws slightly in order for them to read the maximum distance. As you can see on the scale, we have passed the 1 inch increment on the scale. Next, we have passed the just passed the 0.300 thou line, this is also shown on the dial too because it’s passed the 0 measurement. With a dial reading of 10, our final measurement is 1.310 thou. And for one final measurement using the outside jaws on the round stock. Before every measurement, always make sure the dial indicator is zeroed and both the measuring surface of the caliper and part are clean. Use mild pressure on the surface, and always keep that pressure constant. The reference edge determines we have 0.700 thou so far. After reading the dial, we have 24. 0.724 is our final measurement.