Pin Hinges

My Robart drill jig has, on the odd occasion, allowed the drill to break out . Annoying and spoils the surface. Yesterday I took rather more care than usual in lining up the jig. Drilled a couple of test holes in some scrap 3/16" sheet, pushed in a pin hinge and the result was perfect. The first hole I drilled in a 3/16" sheet elevator broke out, as did the third and fifth holes. The rudder was the same result, two good one break out. Finally I found the problem. The threaded end of the drill bush protrudes a little below the surface of the jig body, this allows the jig to rock slightly. I packed it out with a washer from the scrap box. Ten test holes, not one broke out. Won't need to go to SpecSavers after all.