Help Drilling AR500

[smoke]

The challenge is to drill a pilot hole in this material. It is about 500 Brinell and we would like about a 3/8" pilot. After the pilot the following work is going OK. To this point we have tried carbide with Simstar 700 coolant. Any suggestions for a better approach woould be appreciated.
Thanks
Norm

[djr76]

Use a 7/16 cobalted screw machine drill at low sfm, drill just deep enough till you get desired diameter of pilot. I'm assuming you are using a center drill and breaking the points?

[smoke]

It is 1" thick plate that ends up with a 18mm hole plus a chamfered relief (82 degrees?) part way through. A friend of mine is doing this. Getting the initial hole through has been his problem. After that the additional operations are going OK. Since I posted he has found he had a CJ7 Kooltwist drill that is doing OK (It is about 3/8) Some research on this and a source tomorrow may solve the problem. We need to have a source in Edmonton AB. Any or all suggestions are for sure welcome.
Thanks
Norm

[DareBee]

I find punching or waterjet to work really well.
18mm is a little too small to punch in 1" though.

Neither of these help with the chamfering.