All mandrel bodies have internal threads at the end opposite of the nose in order to attach the mandrel assembly to the mandrel rod. The mandrel thread specification typically varies with tube diameter. Although there is no official standard, some common relationships have developed over time for non-metric tube-bending machines. For tube diameters around 1″, 1/2″-13 UNC threads are typical, from about 1.25″ to 1.375″ 5/8-11 UNC, and from about 1.5″ to 3″ 1″-8 UNC.
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A complete guide to the principles of the 4-Step set-up for tube-bending tools
This is a printable handbook showing how to implement in four standardized steps the “forward mandrel” set-up for rotary-draw tube-bending machines and establish process control over the so-called black art. The procedure is based upon the guiding principle that the tools make the bend and takes advantage of the inserted design of modern mandrel tooling.