Bulletsnatch
Plastic
- Joined
- Feb 20, 2021
So I'm currently running into a new problem at work where I am drilling an ID of a part with a fairly large tolerance of .330-.350 and a full diameter depth of 2.110"-2.170" and the blueprint calls out for a 114° to 122° drill point at the bottom of the hole. The material is 15-5ph heat treated to 38-42 HRC. The kicker is the radius that makes the shoulder that goes from the diameter into the drill point needs to be .050" - . 070". Our solution is to go in with a 5/16 jobber drill with 118° point to rough out the hole, and form the finished drill point. Then we go in with an 11/32 drill with a .060" radius ground into the cutting ears and the drill tip ground to a flat bottom. Then match up the endpoint on Z so there is no mismatch between the two. They do not want to spend the money on carbide so both drills are Guhring Cobalt. I don't understand why we can't grind a .060" radius into a drill without taking off the drill point. Or even why cant we grind the .060" radius into the cutting ears of a straight flute 118° carbide drill? Why would that not work like a straight flute form drill and get the job done with one tool? When I ask people at work no one can give me a straight answer. Thank you for your time and God bless.