Self-centering mandrel for golf club hosels

A self-centering laser mandrel system in combination with a golf club head having a hosel and a hosel bore therein, the laser mandrel system comprising:

• a one-piece housing comprising a steel material having a hardness value of 59-60 HRC, the one-piece housing comprising
• an upper portion having a first diameter of between 0.40 inch and 0.75 inch, the upper portion comprising a tapered section with a window,
• a lower portion having a second diameter of between 0.15 inch and 0.50 inch, the lower portion comprising a plurality of grooves, and
• a housing bore extending into both of the upper portion and the lower portion,
• the second diameter being less than the first diameter and sized to fit within the hosel bore of the golf club head;
• a laser disposed in the housing bore within the upper portion, the laser comprising
• a beam emitter and a laser housing that is at least partially visible through the window,
• the laser being aligned with an outer surface of the one-piece housing to within less than 0.35 milliradian (mrad);
• first and second o-rings at least partially encircling a surface of the lower portion of the one-piece housing, each of the first and second o-rings disposed within one of the plurality of grooves;
• and
• a plurality of set screws extending through the one-piece housing, contacting the laser, and aligning the laser within the one-piece housing, each set screw of the plurality of set screws comprising a thread locker,
• wherein the first and second o-rings create pressure within the hosel bore to center the mandrel within the hosel bore, and
• wherein the one-piece housing, when the lower portion is inserted within the hosel bore, is operable to measure a loft and lie of the hosel.