Torsion Spline Torque transmission linear rail

thingiverse

A Torsion Spline allows you to transmit rotational force as the torsion spline, a 2mm x 2mm quadrilateral, moves freely through the Motor. This enables changing the target of that mechanical transmission by altering the distance to the motor. This is part of the simplified Zero Gravity Extruder https://www.thingiverse.com/thing:3476266 To achieve this, you'll need an array of six small flanged bearings with a 3mm bore and a 10mm outer diameter, as well as an 11.5mm outer diameter flange and a 4mm width. In addition to the lateral quadratic spline, you'll require a tube made from brass, approximately 5mm in outer diameter and 4mm in inner diameter, with a length of around 60mm. You'll also need one bearing with a 5mm bore, a 15mm outer diameter, and a 4 or 5mm width. Some M3 nuts and bolts will be necessary, as well as an M8 bolt with two nuts (or one self-fastening nut) and one or two bearings with an 8mm bore, a 22mm outer diameter, and a 7mm width for the motor holder. In my case, the brass tube fits snugly on the 5mm bearing, eliminating the need to prevent the tube from linear movement. The herribone gear is attached to the tube, along with the bearing array. I modified Christopher "ScribbleJ" Jansen's Herringbone Wade's Gears Script to produce a small gear with a thicker shaft. The scripts are included (though I didn't clean them up after my initial try-and-error attempts at Scad programming). If you increase the distance between the motor axis and the brass tube axis, it becomes possible to arrange the bearing array above the motor, which may make it look better. Nutholes with heavy loads feature hexagonal sinks for nuts, while normal nutholes are conical and work fine with just drilling a M3 screw.