Solidworks – mechanically accurate gearbox

By Nulltek

As an advocate of opensource, I’ve been using freecad as my day-to-day modeling software in recent times, which is actually a very powerful tool once you know how to use it. However in my professional and educational career, I have a wealth of experience using Solidworks. Looking back through some of my university backups I stumbled across one particularly fun project, the mechanically accurate gearbox.

The final gear train inside it’s arcrylic enclosure

The project was a pretty open ended design problem: build a gearbox within these dimensions, that looks awesome and is simulated using mechanical motion rather than a simple gear mated animation. This required a lot of research into tooth design and the mathematics behind involute curves ect. The grade was determined by the gear types used, the mechanical accuracy, the aesthetic value, and attention to detail. There was potential to sink hours and hours into this for very little resulting benefit.

My primary aim was to get bevel gears going. This took hours of deciphering machining textbooks and formulating equations for the involute teeth profile and the achieving the nice 90 degree shaft angle with no collisions and little play in the mating. Through a little luck I finally managed to get a 1:1 bevel mating that fit within the dimensions.

The bevel and spur gears.

I also added some spurs and a cage gear to add something interesting aesthetically. The overall gear ratio was just 1:-1, reversing the direction of shaft movement, albeit through an overly complicated train of gears. I also designed some 608 bearings and circlips to hold all the shafts on. I was pretty pleased with the outcome, and at the time was definitely the most complex thing I had ever designed in solidworks.

This was an interesting project to throw at electronics students, and if nothing else gave me a good handle on the solid-works software, and the complexity of mechanical simulations/assemblies.