Lay a folded towel about eight inches behind the ball and hit the ball without touching the towel: a fat swing bottoms out early and runs into it, a good one passes over it and takes the ball first.
Hit the ground before the ball and the shot comes out heavy and short. That's a fat strike. The towel drill catches it. One towel, one rule: hit the ball without touching it.
Why it works
A good iron swing is still coming down when it reaches the ball. It bottoms out just past it. A fat swing bottoms out early, behind the ball, right where the towel lies. So the good swing passes over the towel, and the fat one runs into it.
Set it up
Fold a towel and lay it on the ground behind the ball, on the side away from the target. Set its front edge about eight inches back. That's a good place to start. We're using a seven-iron.
The rep
Make your normal swing. Ball first, then the turf. Slowed down, the club passes over the towel, takes the ball, and only then reaches the ground. If the club catches the towel, it reached the ground before the ball.
What good looks and feels like
Good looks like this. The towel hasn't moved, and the divot starts at the ball, not behind it. It should feel like the club brushes forward through the turf, not like it's chopping down.
Common mistakes
The closer the towel, the harder the drill. Too close, and even a good swing will clip it. So start where you can miss it. And don't lift the ball to stay clear of the towel. That scoop is the swing the drill is there to stop.
The practice plan
To practice it, lay the towel, hit balls without touching it, and check where every divot starts. Hit three sets of ten. Once a whole set misses the towel, take it away and see if your divots still start at the ball. It works for chips too. Set the towel one clubhead back, laid flat, and brush the turf in front of it.
Close
A towel you never touch, and a divot that starts at the ball. That's the towel drill.