You should get this on Level 6 - shoot the ball to the far right gap at about 10% from vertical, and there's a contraption that will blow the ball into the middle section. The odds are very good indeed that you'll get 8 bricks in a row because the contraption keeps blowing your ball back into the middle section.
If you don't get the cheevo after 30-45 secs, I would restart the level.
The odds are good that you'll get the Hands Free and Serious Skills cheevos too:
The Hands Free achievement in IonBallEX (WP) worth 11 pointsIonBall is in play for more than 30 seconds without touching the bat