35 - Revolving Tool Station, страница 8
FINE TOOLS VIAL HOLDER Once the mortise is completed, you can concentrate on the vial holder. In addition to securing the vial, the holder has a built-in adjustment system that lets you calibrate the level. adjustment system. The key to this system is a pair of compression springs (like you'd find in a ball point pen), see photo above. Each spring fits over the end of a machine screw that passes through the vial holder and into a threaded insert in the level. As you tighten the machine screw, the spring compresses and exerts pressure on the bottom of the holder. By turning the screwy you can vary the amount of pressure. This moves the end of the holder up or down which adjusts Vial Holder_ The vial that's used to check a horizontal surface for level is housed in a small U-shaped holder, see photo at right. This holder fits inside a deep mortise in the body of the level. adjustable. The unique thing about this holder is it's adjustable. This simplifies the initial calibration. (For more on this, refer to page 11.) And it allows you to "tune up" the level in case it gets knocked out of adjustment. cut mortise. Before making the vial holder, the first step is to cut the mortise for the holder, see Fig. 5. Besides being fairly deep (1"), this mortise is also quite wide (%"). This means that the sides of the level near the opening for the level vial will only be 3/ig" thick. As a result, any variation in thickness will be quite noticeable. Fortunately, cutting the mortise so each side is identical in thick ness isn't that difficult. What I found worked well is to drill a series of holes with a Forstner bit. Just be sure that the level is secured firmly in place when drilling each one. (I clamped it to a scrap that was squared up and attached to CLAMP LEVEL TO FENCE the table on the the drill press.) After removing most of the waste, it's just a matter of using a chisel to clean up the ridges on the sides of the mortise and to square up the ends, see Fig. 5b. NOTE: CENTER MORTISE ON LENGTH AND WIDTH OF LEVEL s"-DIA. RSTNER BIT DRILL 3"-L0NG MORTISE 1'/s" FROM TOP OF RECESS NOTE: CUTAWAY SHOWN TO SEE WASTE V 1/z"-LONG x 14" I.D. COMPRESSION SPRING 0-32 x W Fh MACHINE SCREW (BRASS) %" X W VIAL Ve" WASHER 6-32 x !4" THREADED INSERT (BRASS) 8 ShopNotes No. 35 |
