M13.5 x 1.0 HSS Left Hand Thread Tap

The M13.5 x 1.0 HSS Left Hand Thread Tap is a bottom tap for metric threads. The tap drill size recommended for this tap is 29/64", which is approximately 11.475mm. It is important to use a good tap drill size that is 85% (±2 pp) of the major diameter for coarse threads and 90% (±2 pp) of the major diameter for fine threads. According to the FAQ, the metric tap drill size for this tap is the diameter minus the pitch, which would be 40.5mm. This tap is made from high-speed steel, which ensures durability. Overall, customers seem satisfied with this product. The FAQ section provides helpful information for customers regarding tap drill size and initial drilling size. The fact that this is a bottom tap is also useful information. One downside is that the product information could be more clearly stated on the website.