Update 6/15/20: Created taller version that prints right side up, for my router table fence adjustment clamps using Toilet Bowl to Floor hardware(1/4-20 x 2-1/4). It's meant to hide the excessive length of the screw.

Update 4/30/20: I revisited the STL file and made the through hole large enough to push on 1/4-20 bolts rather than thread on. Also the hex hole for the 1/4-20 nut is upsized to slide on easier while still being close enough to provide great torque on the nut without stripping. I exported the STL as millimeter this time due to it being default on most printers. If it shows up too large or small on your slicer program you are likely scaling off by 25.4, though hopefully that is fixed now.

This is a knob for hand tightening a 1/4-20 nut. I developed this to use with this Reversible T Slot Hold Down Clamp https://www.thingiverse.com/thing:21057 on the copy of the Mostly Printed CNC Router http://www.thingiverse.com/thing:724999 that I built. Kudos to both those guys their parts are awesome. Also works great for holding the bricks on a Maslow CNC, it got pretty old taking those on and off during my z-axis upgrade (pictured here) Will update with link later once I add it to Thingiverse.

I designed this in OnShape, if you want to tinker with it, it's located here:
https://cad.onshape.com/documents/34659a4532d249bb6686a0e9/w/db9eed1c2bbe89098c45bb02/e/a4e4fa44a7f06fbe9a30a600