Yet upon noticing a handy-looking router table fence micro adjuster in a catalog, I was tempted. It looked straightforward enough. I studied the item in the store and figured, 24 tpi on the lead screw, well, let’s see, that’s 1/24″ per turn, 1/64″ = 3/8 turn, .004″ = about 1/10 turn. No gradation markings. . . forget it. It would not be easy to move the fence a discrete tiny numerical increment, and why else would I want a micro adjuster?
So how do I accurately adjust my router table fence? The answer is: as directly as possible, preferring consistency over absolute measurements, and using one-sided tolerance woodworking techniques which are easily compensated. For example, if I want grooves for a drawer bottom to be 3/8″ from the edge, I set the fence to a reasonably close 3/8″ and plan the work to cut all the parts with that setting. As an example of one-sided tolerance, to cut a rabbet, use the part that will fit in the rabbet to adjust the fence, adding just a hair of depth. The slight excess of lip is easily trimmed after assembly, whereas too little depth would require lots of corrective planing.
There are rare circumstances, however, when it is helpful to move the fence a tiny, specific numerical distance. If I make a cut with the router table and, for some reason, I do not want to alter the mating part to fit, I use .001″ resolution calipers to measure the difference between the cut part and the mating part and thus the amount I need to move the fence to accurately finish the cut.
I use one screw to attach an inexpensive dial indicator to a stick which gets clamped on the table with the tip of the indicator against the fence. The fence is then moved according to the direct readout on the indicator. It would be possible permanently rig a dial indicator to the fence and table but that would be too fussy for rare use.
Alternatively, without a dial indicator, to retract the fence, clamp a block to the table near the end of the fence to register the initial fence position, loosen that end of the fence, interpose a feeler gauge, snug the fence up to it, and retighten the fence. To advance the fence, set the feeler gauge against the fence, snug up and clamp the block against it, loosen the fence, remove the feeler gauge, bring the fence against the block, and retighten the fence. The increment at the bit is half the measured amount at the end of the fence. These procedures are far easier and more intuitive to do than to read or write them!
For bit height, I also like to work directly, but if a measured movement is needed, the very fine adjuster with marked gradations on the Bosch 1617 router works well.
In summary, I adjust the router table fence with direct, low-tech methods the vast majority of the time, and very occasionally employ simple methods using basic multipurpose tools (that I already own) to produce specific measured adjustments.
And I saved myself from another mind-cluttering, special-purpose gadget.