Beginner

I have had this conversation a dozen times. A shop calls and says they tried gun drilling on a manual lathe, snapped the drill in the first hole, and want to know what went wrong. The answer is almost always the same: coolant pressure, pilot hole, or feed rate. Sometimes all three. Here is what I see most often. Failure 1: Not Enough Coolant Pressure This is the #1 first-time killer. A standard lathe coolant pump puts out 20-50 psi. Gun drilling needs 500-3000 psi depending on diameter. The difference is not subtle — at 50 psi, chips do not move. They pack behind the drill and the torque spikes until something breaks. ...

When I started in deep hole drilling, I didn’t understand why the experienced operators spent so much time looking at the chips coming out of the hole. They’d pick up a chip, look at it, and then adjust a parameter. It seemed like magic. My mentor explained: “The chips tell you everything. Short and broken means you’re cutting. Long and stringy means you’re rubbing. Fine powder means you’re forcing it.” ...