Straight-flute STI (screw-thread insert) taps move chips into the taps' flutes but do not evacuate the chips as the taps are rotated into a hole to cut threads. They are used for creating oversized internal threads in blind holes and through holes so that a helical-coil screw thread insert can be inserted in the hole. The insert distributes the load across the length of the threads and improves the threads' strength when a fastener with a standard screw thread size is installed in the hole.