I am having some trouble with tapping some parts. I am normally quite comfortable with threadmilling, but have done very little tapping because I am typically threading bigger holes. I am trying to tap a set of 10mm-1.5 pitch and 8mm-1.25 pitch holes. The holes go all the way through a 1" thick part which I would estimate to be around 38 HRc. The holes were predrilled to .335" (8.5mm) and .265" (6.75mm).
The posted tapping code for the 10mm-1.5 comes out like this:
T7
M6
T8
S60M3
G0X1.2303Y-2.1309
G43Z3.H7
G84X1.2303Y-2.1309Z-1.1787R.025P2000F90.
We tried to run it and the machine alarmed out and the tap broke. I am not sure what the Feed Rate of 90 is there for at the end of the G84 line. Does anyone see anything amiss or know of a tapping tutorial I could look at to see if there is something I am doing wrong? It seems pretty straight forward. The only other thing I've tapped in 3 years was a 1/4-20 in cast aluminum. That went fine, but it probably wouldn't have matter how fast that was going either.
Thanks!