micro adjustment jig

Micro Adjustment Jig By Larry Martin

After reading about all of the benefits of micro-adjustments I decided it was finally time to make one. Took me all of 10 or 15 minutes. I had a scrap of maple 1 by 1 1/2 x 5 inches long. I found a threaded insert, three-eighths inch diameter, No. 20 threads. On the drill press I used a brad point bit to drill a five-sixteenths inch hole into the end of the stock about 1.5 inches deep. I couldn't get the threaded insert into the hole so I used a three-eighths inch bit to enlarge the first quarter inch of the hole. Then I could fit in the insert and used a large screw driver to screw it into the hole being careful to keep the insert perpendicular. Once it was in, I threaded a 1.5 inch No. 20 thread hex bolt into the threaded insert.

To use it I will clamp the 5-inch length of the stock to the tablesaw rip fence mounting bar or to the router table work surface and then set the fence, either the tablesaw fence or the router table fence snugly against! the head of the hex bolt. If there is any trouble with either fence fitting against the bp;t head I will just position a spacer block of wood between the fence and the bolt to make for a good fit.

Now make the test cut and measure the results. If any adjustment is needed loosen the fence, turn the hex bolt either in or out as needed, reset the fence snugly against the Micro Adjuster and make a second test cut. Keep adjusting until you have the perfect measurement.

For No. 20 threads, one full turn of the bolt would move the adjustment three-sixty-fourths on an inch. For one-sixth of a turn, that is, moving the flat on the hex bolt that is uppermost just slightly until the next flat is now now uppermost, the adjustment is one-one-hundred-twenty-eighth of an inch.

An alturnitive to a threaded insert;

Instead of using thread insert you could substitute a T-nut, a/k/a Tee-nut, and used either a hex bolt of even a threaded rod. I like the threaded insert best because those threads stick into the end of the wood block so firmly. and the fit of the hex bolt into the threaded insert seemed to be firmed than the threaded rod into the T-nut that I have.

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