Atlas 618 Craftsman AA 109 6" METAL LATHE METRIC TRANSPOSING 37/47 COMPOUND NYLON GEAR This is a FDM made Nylon gear stack (compound gear) 1/2 Keyed Bore (We can make it with 3/8 bore if you prefer) This gears made out of Nylon - tough and flexible plastic No lubrication required Runs quieter and smoother than Zamak Only Nylons should be used for gears where a slippery surface is desired. All other materials (PLA, ABC, PET, etc.) will grind creating a plastic dust and eventually fail! For details, please review all pictures and compare to OEM gear shown Do not waste your money for ABS, PLA plastic gear that may strip or melt The (47/37) gear is commonly used for transposing the feed rates on metal lathes for cutting metric sized threads The 47/37 ratio is 1.27027 is very close to 1.27 with margin of error of only 0.0026" per foot. 37 tooth gear face .375 (3/8") 47 tooth gear face .375 (3/8"), OD: 2.042" Stack Thickness .750 (3/4") Center bore .500 (1/2") with dual 1/8" key way 24 Diametrical Pitch Thank you.