Fracs CVT

The new Fracs CVT by Fractal Gears.

To measure a frac in 3D Cadd use a sphere to circumscribe the frac, and use that diameter. To measure a built Frac, you will need a special multijaw micrometer (usually available in 3,4 or 5 jaws). This type of tool is commonly used to precisely measure multiflute cutting tools.

Your software will either load in mm or inches or it will ask what you want. For this Fracs CVT set, the circumscribing sphere is not 2 inches/mm as in past Frac builds, but 2.080 mm/inches (2p080 in file names). 2 Inches measurement prints well on most printers at .150 mm step. If the STL part files load in metric milimeters (mm), to get the 2.080 inch size, scale uniformly by 25.4.

Although I have tried to keep everything on my page the same scale, don't mix up this set with previous posted sets because they are likely not the same scaling and will probably not interoperate.

While everything here can be 3D Printed, The Trilobed Disk is a little tricky. You will have to 3D print it from like PEEK, ULTEM , or stronger materials such as CCF, or Metals. Also, CenterHubFrac needs to be equal hardness or it can be worn by the TriLobedDisk. So , a little tricky. If the whole thing were metal 3D printed, it is easy. I will be working on a better TriLobedDisk.

The CenterHubFrac is allowed to wobble an amount constrained by the TriLobedDisk. Torque input and output is at the TrilobedDisks and ToroidalShell. The effective gear ratio is directly related to the input and output torque ratios, so it is a force constrained gear ratio. The force constrained gear ratio can be increased by bringing the TriLobedDisks together, and decreased by pulling apart. The range of movement for the TriLobedDisk is small and around .250 for a 2 inch Frac CVT to go from 0 to 1 gear ratio.

For computer simulations videos check out FractalGears on dlive.tv