MakerFarm i3v X or Y idler belt pulley for 12mm bearings

thingiverse

This is a remix of Zen1's i3v push fit belt guide from http://www.thingiverse.com/thing:359773, leveraging an enhanced version of the original source openSCAD script from Parametric Pulley, http://www.thingiverse.com/thing:16627. The pulley can be used for either the x-axis or y-axis idler in the MakerFarm i3v printer. Changes to the thing:359773 design include increasing the pulley_t_ht parameter from 6.2 to 6.5mm to provide more room for the belt fit; decreasing the idler_ht and retainer_ht parameters from 1.4 to 0.75mm to provide an overall width of 8mm for a better fit on (2) 4-mm wide bearings; increased the additional_tooth_depth parameter from 0 to 0.1mm to help ensure the belt isn't just riding on the compressible teeth of the belt; and increased the number of teeth from 25 to 26 to provide slightly more body between the bearing hole and the teeth (a print quality improvement). The primary change to the openSCAD source from thing:16627 is to provide for chamfer on the shaft hole - very helpful in inserting the i3v 12mm OD bearings. Other changes include migrating to use of MCAD library polyhole for improved dimensioning of holes. Instructions Quality of the printed teeth on the pulley is important. Inspect the printed result for good tooth shape, minimal stringing, etc. Especially with PLA, manage print thermal issues with a print cooler, by printing multiple parts at the same time, or other technique. To install the pulley, press-fit the (2) 5x12x4mm MakerFarm idler bearings into the pulley. Fully inserted, the bearings should be flush with the sides of the pulley. Mount the idler pulley to the i3v using the M5 hardware provided with the MakerFarm i3v kit.