An electrical lapping guide for a magnetic tape head is provided with a resistive transverse stripe with a longitudinal height affixed to a substrate. A pair of leads extend from the stripe with a notch formed therebetween. The notch has a height corresponding to a lapping target limit for associated tape head elements. During material removal of the transverse stripe and the tape head elements, resistance is measured across the stripe and a dramatic increase in resistance indicates that the material removal has reached the notch. A method for accurately machining a magnetic tape head is provided by depositing tape head elements and a resistive stripe with a notch on a substrate. Resistance is measured across leads on either side of the notch for discontinuing machining of the stripe due to a dramatic increase in resistance.