These are the change gears for the 9x20 class of Lathes.
The change gears for the 9x20 import lathes are basically all the same and are sold as Harbor Freight, Jet, and Grizzly 9x20's.
The gears parameters are as follows:
Bore Diameter: 14mm
Keyway Width: 5mm
Keyway Depth: 2.5mm
Pressure Angle: 20
Diametral Pitch: 1 (MOD1 Gears have a DP of 1)
Gear sets are provided for 127x120, 120x80, 60x40, and 48x24, as well as individual gears for 80, 60, 45, 42, 40, 36, 30, and 28.
The SCAD files are also provided so that you can create / edit the gears as necessary to create additional sized teeth gears, or modify the parameters to suit your needs.
EDITED 12/17/13: I had the Diametral Pitch wrong when I exported the gears due to a misunderstanding of the calculation. Sorry! This is fixed now.
EDITED 2/3/14: I updated the gears to now also include text on the gear showing it's tooth count. I have updated the SCAD files as well to include these changes as well.
Print with Teflon or PLA (PLA is stronger and will wear better than ABS) at a high percentage of (recommend) rectilinear infill. Use an infill of at least 60%, for my set I printed them at 80%.