Today we’re building a fully operational, sturdy plywood 3D study model of German engineer Dietrich Uhlhorn’s 1817 invention, the Tachometer, used throughout the 19th century in locomotives and later–and still today–in automobiles. It’s a mechanism that, when the handle is rotated, movement is transmitted through a reducer, increasing the revolutions per minute (RPMs) and displacing twin weights in a rubber band-powered centrifugal unit. The higher the RPM, the more centrifugal force separates counter weights, shifting a movable axle with a flywheel. A dial is fixed to the axle, and the more the axle shifts (the higher the RPM), the more the dial arrow deflects, indicating higher speed rotation. It’s the UGEARS Tachometer, the fourth model we’re testing after the 2-in-1 Arithmetic Kit (reviewed here), the Gearbox (reviewed here), and the Random Generator (reviewed here). The Tachometer is part of the model maker’s STEM Lab series, educational tools and fun models that aren’t just for kids. This kit, like the Gearbox we reviewed, is part of understanding basic engineering assembly design, most apparent in your family automobile.
The box includes everything you need two make the 3D, working, plywood tachometer: 4 sheets of pre-cut plywood, a piece of wax crayon to reduce friction, rubber bands, a press-out tool to ease removal from the sheets of smaller pieces, and connector pieces for optional attachment of the Variator model.
As with the other builds, it requires many parts to be rubbed with the wax stick, and if you don’t align the gears exactly right you will have problems later. The recommended age for building this model is 8 and up.
The instructions were clear (written, with color visuals), and available in 9 languages, and an augmented reality option (QR code links provided) is included for further learning via a UGEARS app. The laser-cut pieces are consistent with the best-in-market quality we’ve found in this series, with no broken or snapped parts. We did have one issue because we didn’t follow the directions–three our of four times we’ve been able to pull the pieces apart when this happens, but we did get a snapped piece, which wasn’t integral to the design. A good reminder to follow the directions the first time. Take your time!
The precision of the model design is fantastic. The mechanism worked on the first try.
No sanding was needed, but there is some coordination required to get some of the pieces to fit precisely. Patience is a must, and you don’t want to force any parts.
The design appears at first bizarre to the eye–you’ll want to read the explanation of the interraction of gears and components in the included (and online) guide.
Instructions and examples are provided to demonstrate how and why each component works. The kit explains that the tachometer is used in mechanisms where it is necessary to accurately track RPM to avoid the negative consequences of overloads. Savvy motorists use tachometers to know when to shift gears (in cars with manual transmissions) and to control the load on the engine, thereby increasing the operating life of their vehicles.
Here is our Tachometer final build in action. Note the indicator reflecting increasing RPMs with greater speed and power:
The model as we built it worked exactly as designed.
The UGEARS Tachometer project is estimated as a 2.5-hour project, and we built it in two sittings totaling about two hours. The fun in this 3D model is getting the RPMs to increase and the centrifugal force with the weights and rubber band in action.
Another great tool for young learners and part of a great science and technology desk set for engineers–and it’s affordable, as of the date of this review it’s listed at about $20. The Tachometer is available here at the UGEARS website and here at Amazon. Next up is our build of the UGEARS Variator which connects to the Tachometer, plus one of the advanced build sets. Take a look at all the available UGEARS models here at Amazon, and check out the UGEARS website for more information.
C.J. Bunce / Editor / borg