Mini Ratchet Wrench

This miniature ratchet wrench is ideal when working with limited access. This one works differently than a lot of the other 3D printed ratchet wrenches that have appeared over the years. Almost all the typical ones have the entire torque loaded onto a tooth or two of the rachet. This one actually acts a little more like a strap wrench, where the torque load tightens the outer ring onto the ratchet, creating a self tightening friction wrench. Hence, all the load is not taken up by the ratchet tooth alone. The interior ratchet is firmly locked into place as you exert a torque. To switch the direction of the ratchet, just flip the wrench over.

I've provided 2 different versions: The first has a standard 3/8" square drive for use with standard sockets. The second has a ¼" hex hole for standard hex shaft bits.

Update (7/20/2024): I've added finger knobs that can slide over the back of the square post (socket model) or the end of your hex bit (¼" hex bit model) that allow you to turn the bit/socket with your fingers, or allow you to hold the bit/socket steady for the ratchet backswing.

I strongly recommend printing this in PLA-CF, as this material will be much harder and stiffer than standard PLA (or other un-filled filaments). Note, though, that you need a high quality CF filament like Bambu's PLA-CF. Many cheaper CF filaments use, essentially, carbon fiber dust rather than actual fibers, resulting in parts that are both weaker and less stiff than standard PLA.

To retain the socket for the 3/8" square drive, a couple of small length of soft TPU filament are inserted into the pairs of holes in either end of the square shaft. This forms a little rubber bump on one side to hold the socket in place. Cut the filament ends off flush on the other side of the square shaft.

To retain the ¼" het bit, there is a small pocket in one of the faces of the hexagonal hole. Take a 5mm long piece of soft TPU filament and press it into this pocket. The filament forms a small rubber bump to hold the bit in place. (Note: the hex shaft finger knob also has the same pocket for adding a bit of TPU filament.)

The ¼" hex tool prints in place with no additional assembly required (except for the TPU piece above). The 3/8" square tool has the square shaft printed as a separate piece. It gets shoved into the square hole in the ratchet. The square shaft has a slight taper, so you need to tap the shaft in place to get a good friction fit.