Change gears (imperial) for EMCO compact 5 lathe

thingiverse

I decided to print my own change gears for EMCO Compact 5 lathe. The feed mechanism comes with six change gears: twenty, twenty-five, fifty and three sixty-tooth gears for common metric threads. Additional gears are required for uncommon threads or imperial threads, including twenty-six, thirty, thirty-four, thirty-five, thirty-six, seventy-two and forty teeth. While you can buy these gears from EMCO in Austria, I wanted to print them on my 3D printer. The gears are five point four millimeters thick with a fourteen H seven bore and keyway. I undersized them for printing and reamed them to fourteen H seven using a hand reamer. As you can see in the photo, they fit perfectly. In the second and third pictures, you can see a seven-eighths by fourteen UNF thread being cut, which uses only the sixty gear from EMCO and three printed gears: seventy-two, thirty-four and thirty-five. Despite being a large thread with heavy cuts, the printed gears work well, hand-cranked. Cutting a seven-eighths by fourteen thread was my primary objective as it is the thread for my single stage reloading press and I am building custom dies. The SCAD file is fully parametric and can be changed as required. You need the parametric involute gears in the same directory, which were written from scratch by me using an example code. I printed at point four millimeters with thirty percent infill and three perimeter in PLA. The credits for this project include OpenSCAD code written by me, stemer114, using the example code from the parametric involute spur gears library. This module makes use of the polyhole library function by nophead.