A tachometer is a tool used to calculate the revolutions per minute (RPM) of a spinning object. Most people associate a tachometer with the RPM dial on their car dashboard. You’re not far off. However, a hand held digital tachometer has some distinctive differences.
Much like its automotive counterpart, the hand-held tachometer calculates revolutions per minute. But unlike your car’s tachometer, hand held digital tachometer models are more versatile, weigh less, and are compact enough to fit in your hands.
In this article, we’re going to focus on two different digital handheld tachometers employing distinct measuring approaches: contact and non-contact methods. Additionally, we’re going to explain how they work, what they work for including a bunch of examples and wrap up with the features we recommend you look for when purchasing one of these devices. Sound good? Then continue reading!
Contact vs. Non-Contact: How do they work?
The most common use case for a hand held digital tachometer is to determine if a motor, propeller, gear or fan is spinning at the desired speed. But which one will work best for your need? That depends on the accessibility of the spinning object and your personal preference. Both contact and non-contact tachometers are available for different types of RPM measuring and both do an excellent job. Notice in the image below, both contact and non-contact can measure RPMs for the same object. You can be confident both will provide consistent measurements.
Images courtesy of Checkline
When using a contact tachometer, the tip of the device, usually called the adapter, is gently held against the spinning object. The adapter senses the movement of the machine and calculates the RPM of the spinning object. Though simple and straightforward, this technique is not possible on all spinning objects, in particular, inaccessible machinery within cages or behind protective equipment. For just these situations, the non-contact tachometer was developed.
When using a non-contact handheld tachometer, a strip of reflective tape is placed on the object that will be measured – prior to turning it on, of course! The tachometer shoots a visible beam of light that reflects each time the tape is facing the light. The number of times the device counts a reflection within a minute equals the RPM.
Do I Need a Tachometer?
Now that you better understand the difference between a contact and a non-contact tachometer, the question is: do you need one? The truth is, if you require measuring the speed of almost any rotating item, chances are good adding a hand held digital tachometer to your toolbox is a wise choice.
A tachometer is most commonly used to determine the speed and RPMs of small motors, engines, gears or fans, as we previously mentioned. Those use cases alone cover thousands of different situations. However, the versatility of the device is considerably greater than the traditional use cases. For example, a digital tachometer can be used to calibrate larger tachometers found in cars and aircraft. They can measure the RPM of lawn mower blades, tractor PTOs, industrial printers, machine lathes, generators, and boat propellers.
To put the simplest ‘spin’ on this as possible, if it rotates you can measure it with a hand held digital tachometer.
What to Look For When Buying a Digital Hand Held Tachometer?
There are a significant variety of handheld tachometers on the market, with varying functionality, quality, and prices. Therefore, our best suggestion is to look for a tachometer that works best for your specific project.
For contact models, look for devices with a durable adapter. Many of the inexpensive contact models feature cheap rubber adapters that wear out quickly. Because rotating devices are not always right in front of you, look for a lightweight model. Trust us, your arm will thank you as you’re reaching to take the measurement.
For non-contact models, we recommend picking those that feature visible projected light, so you know where you’re aiming. Make sure it comes with enough reflective tape to get a nice, long life out of the device without needing replacements. Finally, battery life is key. There is nothing worse than getting to the job site only to leave again in search of replacement batteries.
On both types, look for built-in memory to store previous RPM measurements including maximum, minimum, average, and last reading. This will help keep your measurements organized over time while also limiting the need to re-measure.
At this point, you’re probably wondering why the two devices are separate. We did, too. That is why we recommend buying one model that has both options built in! Now let us introduce you to the Checkline CDT 2000 HD Handheld Digital Tachometer.
Checkline CDT2000 HD Kit
Weighing only 10 oz (with the tip attached) and measuring 6 x 2 5/8 x 1 1/4 (or 8 3/8 x 2 5/8 x 1 ¼ with tip) this device is portable enough to carry with you every day while providing exceptionally accurate contact and non-contact measurements. Designed by German engineers at Checkline, this device is extremely accurate, down to 0.02% with a resolution of 0.01 RPM.
The Checkline CDT 2000 HD lasts, too. Using just two AA batteries, it lasts for 40 hours of continuous use!
The kit comes complete with slide-in contact adapter, 6” and 0.1 meter surface speed wheels, cone tip, funnel tip, extension shaft, reflective tape, two AA batteries (1.5 V), calibration certificate, and operating instruction manual all packaged nicely within a durable carrying case.
Checkline CDT 2000 HD Kit Components
Before we started selling tachometers, we evaluated other models and found they fell short of our quality, consistency, and longevity goals for this new product line. Checkline did not; therefore it is the only brand we recommend. They are truly the best handheld digital tachometers for the money. The question is: are you ready for your next handheld digital tachometer?