Tertill Robot DIY Whacker Hub

thingiverse

This is an alternative whacker hub for the Tertill by Franklin Robotics. My garden soil is clay with many small rocks, which quickly chewed through the original stock of replacement whacker lines in a few weeks. This custom part allows standard weed whacker line to be used, secured with a M3x0.5 grub screw. Determining the length relative to the flexibility of the whacker line is crucial, as the Tertill whacker motor will stall if the line encounters much resistance. Since the hub is friction fit to the Tertill, tight tolerances are required. The guide holes in this part should be bored with a 2mm bit after printing. Print this part on the flat face with at least four shell walls (1.6mm shell) and 25% infill. The additional walls provide needed margin for drilling the holes and support for the grub screw threads, while the extra infill offers a similar weight to the stock part. If you don't have metric bits, use a 5/64 in place of the 2mm bit. Using a 3/32 to countersink the grub screw hole makes it much easier to start the screw. The fit on the motor shaft will be very tight - exercise care not to damage it. For your convenience, here are some recommended parts: [Metric Grub Screw Assortment](https://www.amazon.com/Hilitchi-260pcs-Socket-Assortment-Plastic/dp/B014OMFU1I) and [Arnold .065-Inch Maxi-Edge Commercial Trimmer Line](https://www.amazon.com/gp/product/B002S47CCK).