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Some people can get excited about science simply by watching an episode of Discovery’s How It’s Made But it often takes only one personal discovery, some object in motion, a curious force of nature, or unthinkable technological improvement, and suddenly a wider world opens up.  For me it was my dad making a simple telegraph machine, and later it was marveling on my first flight on an airplane, at last realizing visually how clouds cast shadows on the earth.  Today we’re featuring the final build in our trials of model maker UGEARS′ Stem Kit series of 3D engineering models (check out our other builds if you missed them: the 2-in-1 Arithmetic Kit (reviewed here), the Gearbox (reviewed here), the Random Generator (reviewed here) and the Tachometer reviewed here).  Today’s build is a fully operational, sturdy plywood 3D study model of inventor Milton Othello Reeves’ 1879 continuously variable transmission (CVT), or Variator, first used in sawmills, woolen mills and other Industrial Revolution mechanics, as part of car engines and any machine requiring a smooth changing of gear ratios.

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No glue needed, no sanding required, with everything contained in the box, the Variator is part of UGEARS’ STEM Lab series, educational tools and fun models that aren’t just for kids, a way any family can spark an interest in science, and specifically understanding basic engineering assembly and design.

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The UGEARS STEM lab Variator is a completely functional wooden copy of a belt-driven friction cone CVT.  The drive ratio is varied by moving the belt or wheel up and down the axis of a conical roller.  The belt is powered manually with the help of the reducer.  The rotation is then transferred to the cone pulleys.  Change the gears with the help of the transmission fork and builders can see how the driven cone pulley speed increases or decreases while the drive cone pulley’s speed remains unchanged.  Because of the model’s open design, the whole process is visible in order to satisfy inquisitive minds.

The box includes everything you need two make the 3D, working, plywood Variator: four 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 Tachometer model.

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As with the other builds, it requires many parts to be rubbed with the wax stick.  This model doesn’t have as many gears as the past sets we reviewed, so reducing friction is less of a concern here.  The recommended age for building this model is 8 and up.

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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.  The toughest parts of the build are aligning the cone components.  Also, some of the fittings were tighter than we found with prior kits, so expect the beginning of a few calluses on your fingers before your build is complete.  Always follow the directions the first time.  Take your time!

The conical design is incredibly intriguing.  The mechanism worked on the first try.

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Instructions and examples are provided to demonstrate how and why each component works.  The kit explains more about the “why” behind the components and functionality of this machine.

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Here is our Variator final build in action.  Note the speed does not change as the shifting of the belt occurs.

As we mentioned above and in our review of the UGEARS Tachometer, these sets can interconnect.  Here is the result:

Note how the belt shift allows more power in the Tachometer, and you can watch the pin move to reflect the increase in RPMs.  When the Variator is attached to the Tachometer, the altering rotational Variator speed of the driven pulley is transmitted to the reducer of the Tachometer.  Consequently, the centrifugal force on the weights will be increased or decreased, and the flywheel axle will be changed, in its turn deflecting the indicator on the dial to a lower or higher value.  So changes to the transmission ratio in the Variator will decrease or increase the RPM of the Tachometer.

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The model Variator–and connection to the Tachometer–as we built them, worked exactly as specified.

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The UGEARS Variator 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 the strange, artistic design, and how it all comes together to operate the belt so smoothly and effortlessly.  The big win is the link with the Tachometer.  The connection to that kit only took ten minutes.

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 Variator is available here at the UGEARS website and here at Amazon.  The connectable Tachometer is available here at the UGEARS website and here at Amazon.  In addition to the other STEM kits we reviewed, linked above, UGEARS offers four other STEM kits you may want to check out: a Differential gear, a Counter, a Pendulum, and a Curvimeter tool, and outside the STEM series are other engineering marvel kits like the Pneumatic Engine and Dynamometer, plus many stunning, elaborate, advanced kits.  This isn’t our final UGEARS build–Next up we’re leaving the STEM series to make one of the UGEARS advanced build sets, an awesome fantasy 3D Windstorm Dragon model.  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