Harbor Freight Gearbox Conversion to Ball Bearing Support on a Diet by dz1sfb

Last crawled date: 3 years ago

This project came as the result of having to parse down the previous BB printed gearbox housing to fit inside the designated chassis. Here is the original project https://www.thingiverse.com/thing:2761685
I originally employed a Harbor Freight cordless drills for drives on both sides of my 12 lb bot, as well as the weapon lift. You can use the stock gearbox housing, but it is only bushing supported, and would therefore require periodic greasing to keep things lubed and cool. The bottom line is that the HF gearbox is not designed for side loads that the driveline will impute to it.
So here it is; mountable from three different sides with M5 fasteners. The gearbox is held together with three M4 x 35mm long button socket head screws.The motor attaches to the gearbox cover with the same fasteners as it was attached with the original gearbox. The original snap ring and one of the thrust washers completes the assembly with minimal endplay. The bearings are 28mm OD x 12mm ID x 8mm high shielded, and I got them through Fastenal for $1.49 each. Two required per gearbox.
Bearings https://www.fastenal.com/products/details/0474374?term=bearing&r=~%7Ccategoryl1:%22603582%20Power%20Transmission%209and%20Motors%22%7C~%20~%7Ccategoryl2:%22610631%20Unmounted%20Bearings%22%7C~%20~%7Ccategoryl3:%22612457%20Ball%20Bearings%22%7C~%20~%7Ccategoryl4:%22610637%20Radial%209and%20Deep%20Groove%20Ball%20Bearings%22%7C~%20~%7Csattr01:%5E12mm$%7C~%20~%7Csattr02:%5E28mm$%7C~
Fasteners http://www.mrmetric.com/M11836
You can modify the output shaft as desired. Mine is getting converted to a .375" Hex.
All this work for my 12 lb bot, which is here https://www.thingiverse.com/thing:2602044