Performance & Hotrod Business - July '15

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July 2015 n PRECISION ENGINE n 5 an alpha or a numeric-coded tap. You can refer to the charts here to determine what decimal-inch equivalent is represented by an alpha or numeric drill, but you'll need a caliper to measure the drill O.D. in order to identify the bit. After drilling the hole, it's a good idea to slightly chamfer the hole entry. This will remove any raised edge burr around the hole perimeter, which will aid in tap insertion as well as bolt insertion down the road. The hole edge can be chamfered with a tapered chamfering bit, or with a hand-operated deburring tool. Using a Tap When you need to create threads in a hole, a tap will be required. Threads can be tapped by hand (securing the tap's square drive end in a tap handle, or tap wrench, and turning the tap by hand); or the workpiece may be secured in a lathe chuck (where the workpiece rotates) and the tap secured in a drill head that is sta- tionary on the lathe. The lathe must be adjusted down to its lowest speed, and the drill head must be Here's a different style internal thread chaser. Instead of a dedicated thread-size chaser bit, this fea- tures a driver and a set of chaser heads in a variety of sizes, (available in fractional and metric). Shown here is Snap-on's TR25M. (Photo courtesy Snap-on) An external thread chaser. This type (Snap-on TR20) is adjustable for thread diameter and features a set of chaser bits. Available in both fractional and metric formats. Good for clean- ing up studs or bolts. (Photo courtesy Snap-on) Split-die chasers are designed for restoring wheel stud threads. Kits include all popular fractional and metric sizes. The split die is placed onto the base of the stud, with the flat hex end seated against the hub face. A socket wrench captures the halves together. The die is then rotated outward toward the stud tip. 1-800-533-8010 • Made in America And Proud of it! Goodson Tools & Supplies for Engine Builders is proud to offer a wide range of Made In America products. We're also proud to say we're celebrating our 70th Anniversary as an American Made company! Look for the American Made symbol in our catalog and online! Now Offering

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