No kidding taps break VERY easily. My rule #1 is to always buy the
best quality taps. Expensive and hard to do for jewellery sized taps.
If your set was made in India or etc. beware, Swiss or US are much
better. One case where $ is not a concern.
For tapping you need the right hole size, maybe 60 -70 % thread
engagement. Bigger holes greatly improve your odds. Put another way,
if your desired screw size in 1mm tapping a 1mm hole will ruin your
day, 1.1 -1.2mm much better odds with very little loss of strength. I
don’t have exact numbers for you but a bit of time spent with google
is a good investment, a broken tap is the best way to ruin (and
waste) a day.
The alignment of the tap with the hole is critical, drill the hole
with a drill press if possible and use the same set-up to start the
tap if possible. Use cutting oil, best are ones sold for threading.
Get the tap started, maybe a turn or two. Back off 1/4 turn to cut
chips and then another 3/4 turn. Repeat until done, maybe back the
tap out completely to clear chips every now and then. Gentle… if it
feels bad it IS.
Dies are much much more tolerant, get them going at 90, oil, and chip
Hot alum or fresh pickle is good for dissolving broken taps And
you WILL break some. On a more cheerful note I found that as my
broken tap skills (painfully) the incidence of broken taps decreased.
Always around to answer questions, my auto pilot bench skills are
usually better than my explanations, I’ve got to think to type.