***  Straight Shank for use with a Collet Chuck.

*LIFETIME WARRANTY*   1/2" (.500") Expanding Mandrel with a 5/8" Straight Shank for use with a Collet Chuck.  The call portion of the mandrel is ≈2.6" long.

The EXM Series Mandrels are made from 4140 Steel, and uses the more robust NPT expansion plug design for added durability.  The EXM Series Mandrels are knurled on the body of the mandrel.  Un-knurled EXM mandrels are not available.

Expanding mandrels have a limited range of expansion before damage to the mandrel can occur.  Typically your bore should not be larger than .010" over the size of the mandrel.  Though the mandrels will expand beyond that point (some more than others depending on model and diameter), alignment will suffer if the bore is any larger than mandrel and at a certain point the mandrel will be damaged and could become unusable if the bore is oversized by too much.  If you have issues with a mandrel holding a blank, the first thing you need to do is inspect your bore.  Measure each end with, at the least, a dial or digital caliper (something that reads in thousandths of an inch) to identify the actual size and if there is any taper.  Any more than .010" oversize and you will need to look into your drilling equipment and address the issues there, or look into drilling undersize and using a chucking reamer to bring the hole up to size.

This is the recommended mandrel for a beginner who has a collet chuck.

Requires a 3/16" Allen Wrench for the expansion screw.  Replacment expansion plugs are readily available at any hardware store - they are 1/8" NPT Socket head pipe plugs and also available in the Mandrel Parts Category.