![]() ![]() Last tapping tidbit: For the hardest materials, and especially when the cost of a broken tap is very very high, consider thread milling. Everbody I read suggests Moly-Dee is the one to choose. Check out our Drill Tap Size Chart and Calculator for the details–seriously good stuff there!įourth tapping tidbit: Use tapping fluid–your taps will thank you all most as much as they did when you pulled that thread percentage trick above. That all comes from selecting the right drill size. Third tapping tidbit: Would you like to know the ultimate secret to maximizing the life of your taps? It boils down to selecting a thread percentage that gives you enough thread strength while minimizing the torque that must be applied to the tap. Peck tapping is also an excellent way of clearing the long stringy chips often found when machining plastics and some other materials . ![]() Peck tapping is only called for with a cutting tap–no benefit to pecking with a form tap. For the most part, you will need rigid tapping to be able to peck tap because the tap has to get itself synchronized back to the same set of threads as it goes in and out of the hole. Peck drilling is familiar to most machinists, but peck tapping may be new. Second tapping tidbit: you can “peck” tap difficult holes. That information comes from tapmaker Titext via the link I’ve provided. That actually covers a surprisingly wide range of materials including a lot of steels. ![]() But it’s the machinist who decides which tapping style to use depending on the job at hand.While many machinists may think form taps are only for aluminum, the answer to the quick question is you can form tap materials up until they have a hardness greater than 36 HRC, which is about 340 BHN. Compare that to cut threads, which because of the tools used, cause grain structure to essentially fracture.Īlso, formed taps have a longer life, as they last about three to 20 times longer than cut taps.Ĭutting taps and forming taps both have benefits and limitations from stronger threads to greater compatibility. But machinists aren’t limited to the materials when they decide to cut taps.Ĭutting taps also have the upperhand regarding horsepower, as this threading method requires less power than forming taps.įormed threads are stronger because the grain flow of materials is compressed at the crest and root of the thread form. When machinists use forming taps, they can only use the process on aluminum, soft steel and nonferrous metals. The two threading methods tap holes differently, but they also have a handful of other differences, starting with the type of thread each method produces.Ĭutting taps are more versatile than forming taps and can be used with more materials. Additionally, forming taps usually require a larger hole because this style causes a material to thread away and into the threads of the tap. Forming taps involves the displacement of a material (like metal) within a hole. Unlike cutting taps, forming taps create external threads. This gradual cutting motion allows a tap to smoothly enter a hole. This process then leaves an internal thread that meets the machinist’s desires.Ī machinist achieves that geometric precision by using tools that come with a feature called the chamfer, which cuts a 90-degree angle or edge to make it more symmetrical. Cutting a tap means using tools that remove material from the tapped hole, according to North American Tool. When machinists need to create internal threads, they opt for cutting taps. Cutting taps and forming taps produce threads that are interchangeable and gauge identically, but those are the only similarities between the two tapping styles. ![]()
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