B.G. Micro gave me a short digital linear measurement tool (TOL1049 $8.95) which is based on a standard caliper. However, unlike a caliper, this has a spring-loaded slide rather than a pair of jaws. Based on the spring and the mounting holes, I conclude this is a digital indicator, which is the electronic equivalent of an analog dial indicator.
It appears to be an industrial upgrade, as the body is made of stainless steel rather than plastic, and has threaded mounting holes.
BG Micro TOL1049 digital indicator with battery, data cable, and case
The measurement device comes with an LR44/AG13 button cell, data port cable, and cushioned case. The data cable is also compatible with most inexpensive imported calipers. Elsewhere, the cable costs $13.95 (but also includes a mini-DIN connector); so this product may be worth buying just to get the cable.
The thin metal strips that hold the data cable were too tight on my indicator, so I bent them out slightly using smooth-jaw needle nose pliers. The tool’s data output port has the same pinout as other calipers I own.
Industrial digital indicator showing data port pinouts and buttons.
Although notches exist in the front where rubber pushbuttons appear on most calipers, the physical buttons for this tool are actually located at the bottom of the face. When I first inspected the tool, the measurement units kept changing back and forth and the value would randomly reset -- not because the tool was defective, but because I was inadvertently holding the device by the buttons.
Whether analog or digital, a test indicator is often mounted to an adjustable arm to rapidly measure the variance in height, depth, or width of something placed underneath it. It can also be used to measure the relative offset of a rotating piece, such as to center a rod in a lathe with a four-jaw chuck.
Digital indicator held on adjustable magnetic base
However, there’s no reason that you can’t use a digital indicator for other purposes, such as positioning on an x-y table or a readout of the cutting tool depth on a lathe. The price is low enough that it opens the door to being used as a sensor on a variety of pieces of equipment or robots.
The downsides to this measurement device are:
Let’s take a look at one of the best features, the mounting holes...