Compact Nema 17 Gearbox 6.5 to 1 Ratio

thingiverse

BudgeProjects had a good concept but the design needed cleaning up instead of modifying his files, I rebuilt the gearbox from the ground up. Now to correct his gear ratio is not 16 to 1, it is 7.5 to 1, gearboxes like this are calculated using the following simple equation (Driven Gear / Driving Gear) * Number of stages. So therefore his gearbox is calculated as (30/12)*3 = 7.5 With my gearbox I have a ratio of 6.5 to 1, as my driven gear is only 26 teeth. I have also used herringbone gears as they are quieter and a more positive engagement. I use different bearings, on the main output side I have used 623 bearings. BOM 3D Printed Parts 1 x Nema 17 with 21mm shaft 3 x 623 Flange Bearings 1 x 623 Bearing 1 x 6802 Bearing 6 x M3 x 6mm Socket Cap Screws 1 x M3 x 50mm Socket Cap Screw 4 x M3 Nuts My Gearbox design is much more compact than BudgeProjects, apart from a different gear ratio I have much improved on his design and the looks, the use of the nuts is more hidden and the general appearance is better. Although my output shaft is 3D printed it has a M3 Screw core for strength. I currently have the gearbox on the printer, once printed I'll upload some pictures of the assembly and how to assemble the gearbox. Update: I have changed the gearbox as I made a measurement error which meant the M3 axle was unable to be fitted, and a few other minor changes, but I now have an increased gear ratio too. (31/12)*3=7.75 So now the gearbox is a 7.75 to 1 Update 2: After assembly, and checking operation, I put a PTFE grease lubricant over all the gears and ran the motor back a forth multiple times, this worked all the gears into place and got it working, initial operation of the gearbox would need to be done with the lid off to get the lubricant on all gears and get the gears settled down and into position, put lubricant on the inside of the lid to allow the gears to slide on the surface, as the lid is also used to constrain the gear position, continue running the gearbox in both direction multiple times until the operation is quiet, and then it is ready for use.