I bought a router table at a garage sale for a buck, but it was missing a knob.The STL included here is for a 1/4" nut and bolt to match that device, but the SCAD is parametric, you can make any size you like.You could also put a bolt in the captive position instead of a nut if that's what your application calls for.
I'm a computer person who grew up on a farm. I enjoy all kinds of making. Programming, electronics design, rough carpentry, whatever.I am a mentor for FIRST Robotics FRC team 1502, "Technical Difficulties" at Chelsea High School.