Top 5 Dial Test Indicators of 2021
Dial indicators are simply a staple in the machinist tool box. If you are needing to measure for consistency purposes and not comparative purposes, a dial test indicator is the indicator for you. The applications of this popular measuring tool are broad, ranging from tramming your milling machine to measuring the roundness or runout of cylindrical parts.
This article will cover some of the dial test indicator basics such as tool anatomy, usage details and calibration tips, so you can deepen your knowledge on these gauges before checking out the hot dial test indicator models of 2021.
Dial test indicator vs dial indicator
Unlike dial indicators, dial test indicators (or DTI) have a lever-type arm. The angular motion of the lever allows the contact to ride easily over irregularities on part surfaces. Potential alignment errors are measured by how far the arm is pushed sideways. This capability is lacking in dial indicators, because the vertical-action plunger may resist responding to surface irregularities pushing “sideways” against the contact. You can learn more about the differences between DTIs and dial indicators in our article Choosing the Right Indicator.
Understand the precision measurement tool
Using a dial test indicator is not very complicated, but it requires a little bit of patience and practice. The first step, one that many skip, is to understand the anatomy of a dial test indicator, as those parts are referenced throughout the process of using the precision measuring tool.
Any given dial test indicator is comprised of nine main parts
- The dial face showcases the measurement reading and can be oriented in different directions to satisfy the operator’s position.
- The hand/pointer is located on the dial face articulating the given reading.
- The turn counter (not labelled in diagram below) is the smaller gauge seen on the dial face. The turn counter counts the rotations or turns of the needle.
- The indicator cap is found at the top of the face and secures the spindle in place.
- The bezel hugs the circumference of the dial face and rotates for tool calibration and resets.
- The bezel clamp can be found on the side of the face and locks the bezel in place.
- Limit markers are moveable and set parameters depending on the project’s requirements.
- The stem protrudes from the bottom of the face connecting the spindle to the face.
- The spindle is responsible for detecting any imperfections.
- The contact point sits at the very base of the tool and supports the contact that must be made between the indicator and the part being measured.
Time to put the precision measurement tool to use
First, press the contact point against the desired part’s surface. As you press the dial test indicator against that surface, lock the dial test indicator into place and watch the dial as you move the part. It is important to note that test indicators allow just for a single revolution of the pointer around the dial, and the tool only allows for clockwise rotation as opposed to a dial indicator which rotates both clockwise and counterclockwise.
Like any other gauge, dial test indicators need to be calibrated frequently because usage of the tool impacts the tool’s accuracy. Dial test indicators are precision measurement tools, so it’s imperative to keep them…precise. Check out our article Understanding Gauge Calibration for more information.
Your indicator won’t be of much use without a base to hold it firm in place. An indicator base is an essential counterpart to the dial test indicator (and other dial indicators) because it holds the indicator in place to successfully achieve accurate readings. Want to know more? Check out our article Selecting a Magnetic Indicator Base and Arm.
Now onto the fun stuff, for a specific walk through of how to properly use the tool, see below.
To help you discover what model is best for you, we reached out to the Practical Machinist community via Practical Machinist’s social media platforms to learn more about the community’s preferred dial test indicators.
Let’s take a look at the top 5 dial test indicators models recommended by your fellow machinists.
This dial test indicator measures with +/-0.0001” accuracy making this dial test indicator both reliable and affordable. The Best Test model by Brown & Sharpe proved to be the most popular dial test indicator among the Practical Machinist community members.
Featuring an easy to read dial and jeweled mechanism fitted with ball bearings, this tool can achieve up to a maximum measurement of 0.0600.” This dial test indicator is just about as popular as the BestTest dial test indicator among the Practical Machinist community on social media.
This Mahr dial test indicator is shockproof, anti magnetic and the movement bearings are jeweled with eight precious stones. The dial test indicator model has a double lever specifically for overload protection.
This test dial indicator has a replaceable contact point and features a jeweled lever action for smooth readings. The half yellow shading on the dial’s face helps with more accurate readings. Use either a body clamp, friction holder or shank to mount this swiveling, tubular body.
Fowler is known to make a reliable and durable dial test indicator. That’s probably why it’s made its way to the top five most popular dial test indicators. This dial test indicator features a white face for easy readings and can achieve up to a maximum measurement of 0.0300”.
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