Simple Micro Adjuster Jig

Very simple micro adjuster that can be set either loose or tight. Each full rotation moves the micro-adjuster screw 1/20th of an inch. 

Background

I needed a micro-adjuster for some router and lathe jigs I'm making. I had some spare ¼" bolts and nuts, and a bunch of 3d knob designs that also fit ¼" hardware, so …

Choice of hardware

You can use pretty much any  ¼" hex head or carriage  bolt more than 1" long. Just select an appropriate knob from the models

The attachment holes on the body are sized for #6 screws or bolts.

Pieces to print

The minimum print is a body top, body bottom and your choice of one knob. An end stop is optional.

Assembly and friction fit

Using two embedded nuts allows you to adjust the tightness of the screw. First, attach a knob to the bolt of your choice. Then, insert the ¼" bolt of your choice into two ¼" nuts:

Turn the nuts to position them so that they will both slot into the micro-adjuster body (you can use either the top or bottom piece of the body).

The fit is precise. You will need to align the bolts with the slots in the body carefully, oriented so that an edge points down into the body:

However, there is enough play such that turning either nut 60 degrees (so that adjacent faces come into the same plane) is enough to tighten or loosen the friction fit of the bolt. 

This allows you to adjust the tightness of the jig. I recommend marking the bolt faces so that that you can re-find the precise position. I used a sharpie / permanent marker to mark one face T (for tight) and the adjacent face L (for loose).

Once you have the desired friction fit, you can enclose the nuts and bolt using the other half of the body.