How to do when the tap tapping difficulties and frangible?

1.How to do when the tap tapping difficulties and frangible?

(1)The drill is too small: According to the matrix material replaced with a suitable drill diameter.
(2)Drill serious wear and tear caused bottom hole drilled into the cone: Replace with a new drill.
(3)Deflect Bottom: Bottom hole scrapped
(4)Taps and matrix material selected inappropriate: Select suitable matrix material taps.
(5)Caused by use HSS TAP(Ⅱ):Use HSS TAP(I) first.
(6)Taps badly worn:With steel screw tap within the special plug gauge detection，if failure to pass then need replaced with new taps。
(7) When tapping, taps with different heart bottom: proper operation