9-Threads, Taps, and Tapping - Hand Tapping Aids
Hand tapping aides will allow the tap to be manufactured properly and will avoid damaging the part. A broken tap is often difficult to remove and requires special tools like the tap extractor shown.
The tap must be directly straight over the hole. This can be accomplished in a variety of ways. The simplest way is to use a square with two positions 90 degrees apart. The difficulty here is maintaining this upright position while turning the tap.
There are other tools that will keep the tap square and steady, a solid or spring loaded tapping center used with a drill press , a tapping block (last image) or a tap and reamer aligner.
Taps are manufactured with a center hole or have a bevel ground at the square end of the tool. T-handles also come with center holes at the top of its body.
|Be wary of the machinist who says he has never broken a 1/4-20 tap because there is a good chance he is either not a machinist, or he is a liar. R.S.|