Somta - page 88

78
(d) Possible Cause
Excessive tapping speed is applied.
Solution
Use the recommended tapping speed.See page 63/65.
Bell-Mouthed Tapped Hole
(a) Possible Cause
Mis-alignment of the tap and the hole.
Solution
Care must be taken to align the tap with the hole before starting
to tap.
(b) Possible Cause
The workpiece is not rigidly held.
Solution
Secure the workpiece
(c) Possible Cause
Excessive pressure is applied when starting to tap.
Solution
Only sufficient pressure to initiate self-feeding should be applied.
(d) Possible Cause
Insufficient number of threads on the lead.
Solution
Use a tap with a longer lead.
(e) Possible Cause
The drilled hole is too small.
Solution
Use the recommended drill size.See page 55/61.
Over-size tapped hole
(a) Possible Cause
Using the incorrect tap.
Solution
Use the recommended tap.See page 51/54.
(b) Mis-alignment of the tap and the hole.
Solution
Care must be taken to align the tap with the hole before starting
to tap.
(c) Possible Cause
Lack of / or wrong type of lubricant.
Solution