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Expanding Mandrel for LeBlond Manual Lathes
Expanding Mandrel for LeBlond Manual Lathes
An expanding mandrel is a workholding device that grips the interior diameter or ID of a part to support it between centers on a manual lathe like LeBlond’s RKL model. There are a variety of devices such as chucks, collet sets, vises, jaw chucks and special fixtures that do this but an expanding mandrel is unique in that it expands to accommodate the part.
The patented design of LeCount’s expanding mandrel uses parallel expanding jaws that slide smoothly to grip the inside diameter of the part without tool intervention. The expanded mandrel then releases the workpiece to return to its original position. The expanding jaws are manufactured from high-quality 17-4 Series Stainless Steel and coated with Armoloy for added durability and resistance to wear, corrosion, and friction.
Using an expanding mandrel is a good way to ensure consistent and accurate inner case neck diameters that contribute to bullet fit, alignment, and overall shooting accuracy. The process also helps to ensure that the case neck retains a proper internal shoulder.
Prior to expanding the case neck we recommend sizing the brass 0.002" to 0.003" smaller than your desired final bullet tension size (this is assuming that you are using the correct bushing die for that caliber). This will allow the expander mandrel to expand and properly size the neck while still leaving the correct gap between the case and the gage pin.
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