Drilling Square Holes 16 May 2017, 19:00 Sorry, your browser doesn't support embedded videos, but don't worry, you can download it and watch it with your favorite video player! Device for drilling square hole of rounded corners based on the principle shown in “Drilling square holes 1a” « previous mechanism Trochoid Gear Pump next mechanism » Forging With Twisting load comments Please enable JavaScript to view the comments.