The metric system is great, but sometimes you need an inch based version. These knobs are for 1/4-in and 5/16-inch bolts or nuts, and can be used in either the male or female version with the appropriate additional hardware (as shown in the photos).

Note that each knob comes in two versions: short stem and long stem. In addition, the 5/16 knob comes in two handle sizes (small and large).

These are designed to have a tight fit for the nut or bolt used, so they don't slip off in use. I suggest using a matching nut and bolt to pull the nor or bolt head into the knob recess.

OnShape 3D CAD files can be found here:

[https://cad.onshape.com/documents/6ae8bcbe8963fe1a7881e8de/w/1a7c9941cae2f375f93845ee/e/cf83794575fff2d20c8b1c96](https://cad.onshape.com/documents/6ae8bcbe8963fe1a7881e8de/w/1a7c9941cae2f375f93845ee/e/cf83794575fff2d20c8b1c96)

Print instructions

This worked for me with PLA with these settings:

fill : 20% rectilinear
top/bottom fill : concentric
perimeters : 4
brim : not required
supports : not required
0.2mm quality setting