I need to drill a deep, straight hole in a piece of stainless and am seeking advice on the best way to do it on an engine lathe. I haven't decided on the grade yet but I'm leaning towards 416. It'll be 15" deep, just over 1/2" in diameter, and a through hole. The final diameter isn't critical. A few thou off one way or the other is fine, but straightness and consistency is fairly important.
I do have the option of buying some proper gun drilling equipment, but I'm hoping to avoid that if possible. No round tube is available close to the dimension I need.
Since it's a through hole I figure my best chance of success is drilling from both ends so I'm doing 2- 15d holes instead of a 30d hole. After drilling I'll ream to final size from one end. As far as drills, I'm not sure what my best option is. I'm leaning towards starting with a jobber and drilling the rest of the way with an short flute extended length carbide bit. My thinking is the short flutes and carbide will provide better stiffness at the expense of chip clearing ability.
I do have the option of buying some proper gun drilling equipment, but I'm hoping to avoid that if possible. No round tube is available close to the dimension I need.
Since it's a through hole I figure my best chance of success is drilling from both ends so I'm doing 2- 15d holes instead of a 30d hole. After drilling I'll ream to final size from one end. As far as drills, I'm not sure what my best option is. I'm leaning towards starting with a jobber and drilling the rest of the way with an short flute extended length carbide bit. My thinking is the short flutes and carbide will provide better stiffness at the expense of chip clearing ability.