Performance & Hotrod Business - July '15

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July 2015 n PRECISION ENGINE n 9 is a bit trickier than using a tap, since it's very easy to start threading crooked when using a die by hand. Don't assume that the die will automati- cally self-center, because it won't. It's easy to accidentally start the die off-angle. The die must be kept at a 90-degree angle to the workpiece, especially when starting the cut. Pay attention to the die itself, since the cutting threads on one side will be cham- fered, (this side will be stamped "start with this side" indicating the side of the die that Solid/one-piece thread inserts are available in various designs, but are an alterna- tive to a spherically wound insert. While a wound insert retains its position via installed tension, a solid insert requires another means of retention. This exam- ple features small stakes that are hammered or pressed flush with the top surface. needs to make contact with the work piece upon initial entry. This chamfer will help to center the die, but you'll still need to pay close attention to keep the die level, (perpendicular to the rod being threaded). Note: Just as when you're tapping, apply a good tap oil to the threads as you cut, and keep your thread cutting to a slow speed. Especially when cutting threads on aluminum or stainless steel, you'll need to cut slowly to avoid galling and smearing the parent material. Most dies that you'll buy at a hardware or auto parts store will feature a hexed outer face. This allows the die to be driven by a dedicated hex-type die wrench, or with a hex wrench or socket from your toolbox. Round-outside dies are also available for use in industrial equipment such as a lathe. Before you begin to use a die on your project, it's a good idea to practice on some scrap rod of the same material in order to get accustomed to the die's use. Mike Mavrigian has written thousands of technical articles over the past 30 years for a variety of automotive publi- cations, in addition to writing nine automotive technical books for four dif- ferent publishers. Mike also owns and oper- ates Birchwood Automotive in Creston, Ohio, where he builds custom engines, street rods and performs vehicle restorations. Mike can be reached at 330-435-6347 or birchwdag@ Birchwood's website is www.birch- INDUSTRY LEADER MAHLE MOTORSPORTS. Every MAHLE Motorsport piston is backed by over 90 years of racing heritage and technology innovation. By employing the most advanced piston design and machining processes being used today, (many of which are performed on machinery MAHLE manufactures themselves), the MAHLE piston brand has become the choice of race teams worldwide. That's because they offer features including profiled pin bores, dual and triple ovality skirt profiles and tighter tolerances with unmatched consistency. MAHLE's light-weight, low-drag, ultra-strong slipper skirt forging designs truly outperform the competition. All MAHLE Motorsport pistons are dual or triple coated, adding protection and maintaining consistent performance over the life of the engine. These are just a few of the reasons why top professional race teams use MAHLE Motorsports pistons. Rely on the technology leader MAHLE Motorsports, and provide your customers with the winning advantage. 1-888-255-1942 IN PISTON TECHNOLOGY

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