As with all golf clubs, the Rules of Golf state that the angle of a putter’s shaft relative to the ground cannot exceed 80 degrees when the club is in the address position. This lie angle is what makes the putter swing naturally on an arc – slightly inside the target line on the backswing, back onto the target line and even with the ball at impact, and inside the target line again on the through-swing. (Only a putter with a 90° lie angle would be able to swing naturally straight back and through on the target line, like a pendulum.)
Many players may feel like they swing the putter straight back and straight through on the target line, but to truly do this you would have to manipulate the club considerably, which is very difficult to repeat with any regularity. Instead, use this gate drill from Titleist staff member Brandon Stooksbury to build a consistent path that arcs slightly and delivers the club face square to your intended putting line every time.
Putting Path Gate Drill:
Find a perfectly straight putt and set two alignment sticks down, parallel to the line of the putt. The width between the alignment sticks should be just slightly wider than the width of your putter head.
Without a ball, make a few practice strokes, watching your putter head as it travels back and forth.
The alignment sticks serve as a frame of reference to ensure that you are swinging the putter on an arc: As you swing back, the toe of your putter should move farther away from the outside alignment stick. The heel of your putter should move closer to the inside alignment stick.
When you swing the putter back to center of your stance, the putter face should be square and the putter head should be right in the middle of the two alignment sticks (the toe is the same distance from the outside stick as the heel is from the i inside stick).
As you swing through, the toe of your putter should move farther away again from the outside alignment stick. The heel of your putter should move closer again to the inside alignment stick.
Once you feel comfortable, place a ball in between the two alignment sticks and roll a putt, making the same arcing stroke that you first practiced. Done correctly, the ball will head straight through the gate and towards the cup.