Hello! I’m new here, I came across a problem today when I had to drill a .043 hole .375 deep into an A2 tool steel plate. I used a .043 jobber drill that had a .5 loc which might’ve been too long but it managed to drill 10 holes and it then broke halfway into a hole. I was doing 14000rpm, 0.7 in. feed with a .025 peck using flood coolant of course. I then managed to get through the rest of the holes easier and faster using a .041 carbide drill 14000 rpm 2 in. feed with a .05 peck and repeating it with the .043 jobber drill at 5000 rpm 1 in. feed .05 peck to bring hole to size. Although I managed to figure out that the carbide drill works better, is there any other way, method or process that can get this done more efficiently? Thanks in advance for any answers!
Edit: I did spot the holes beforehand .083 90° because of a required countersink.
Edit: I did spot the holes beforehand .083 90° because of a required countersink.