NOW IN STOCK - READY TO SHIP: There are calculators and there are CALCULATORS. I guarantee ya, The Machinist Calc Pro has more answers than you have questions. We saw this at a recent Tool Show and thought we would order some. I have gone through the instruction book, page by page and I was amazed. Let’s suppose you need to add 3.375 inches + 21/32 inches + 27.5mm. Piece of cake. Enter 3.375 (Inch) + 11/32 + 27.5 (mm) = 5.1139272 inches. Oh, you needed that answer in millimeters, simply hit (Conv) and (mm) and you have 129.89375 mm. I did not know there were ten different, ½” threads? They are 12, 13, 14, 16, 18, 20, 24, 28 and 32 TPI. The thread on the collet alignment screw found inside the spindle of your Bridgeport Mill is a ¼”-32. What drill size would you use if you have the drill and tap a new hole. Another piece of cake. Enter 1 / 4 (Thread Size), then enter 32 (Thread Size) (Thread Size) and presto, you get 7/32, for the correct drill size. And then there is the function for laying out bolt holes. I kid you not, enter the center location, the start angle, the bolt circle diameter and the number of bolts and “blink”, there you have all the coordinates just slicker than greased owl snot.