By far the most common flaw in the serves of beginning and intermediate tennis players is meeting the ball too low. You can make a simple device that will train you to hit your serves at full upward extension.
Difficulty: Average
Time Required: 20 minutes
Here's How:
- Get an old tennis ball, four feet of rope, a foot or more of stiff wire, and a drill with one small bit and another between 1/4 inch and 3/8 inch.
- When drilling a tennis ball, the bit can slip. For maximum safety, clamp the tennis ball in a table vise. Otherwise, hold the ball with a heavy, puncture-proof glove or a large pliers or clamp.
- Wear eye protection.
- Use the small bit to drill pilot holes in the ball at roughly 10:00 and 2:00.
- Use the large bit (3/8 inch is ideal) to expand your pilot holes.
- Fold or twist one end of the wire around the end of the rope so that it will hold tight, but keep the wire-rope union slender.
- Poke the wire through the ball.
- Use the wire to pull the rope through the ball.
- Remove the wire.
- Find a horizontal support such as a swingset bar or clothesline that's at least 16 inches higher than your maximum upward reach with your racquet and has at least three feet of clearance in every direction.
- If necessary, string up a short, horizontal rope or clothesline.
- Standing flatfooted and reaching as high as you can, measure the height three inches below the tip of your racquet.
- Tie the rope that passes through the ball into a loop around your horizontal support, with the ball hanging at the height you measured in step 12.
- Use a full service motion when hitting your serve trainer, including stretching up on your toes to hit.
Tips:
- Hit in a direction that will be safe if the ball somehow goes flying.
- Practicing for around 10 minutes a day should make a big difference in your serve.
- If you strung up a line to support your device, you can easily make the height adjustable for different users.

