Since a piebald is a recessive morph, when bred to a normal you would produce all normal looking ball pythons that are 100% het for piebald. Which basically means each baby will carry the pied gene, so when bred to a visual piebald the odds of producing a visual pied is 50%.

But say you bred a normal to a spider(dominant morph), you will get approx. 50% normals and 50% spiders.

Hope that helps.