Holes, Chamfers and Threads

These tools cover making holes and threads. Get bolt circle coordinates, countersink and chamfer depths and drill point length, look up drill sizes and machine screw sizes, and find thread pitch and diameters or the NPT tap drill for a pipe size.

Tools in this group

• Bolt Circle Calculator — Enter the number of holes and the bolt circle diameter to get the X/Y coordinates of every hole, the chord between holes and a drawing.
• Chamfer Calculator — Work out the missing sizes of a chamfer, or how deep to plunge a chamfer mill or spot drill for the chamfer you need.
• Countersink Depth Calculator — Enter the countersink angle and the diameter you need at the surface to get the depth to set, or the diameter a depth gives.
• Drill Point Calculator — Enter the drill diameter and point angle to get the length of the drill point, then the depth the tip must reach for a full-diameter hole.
• Drill Size Chart — Every number, letter, fractional and metric drill with its size in inches and millimetres. Type a size to see the nearest drills.
• #6 Screw Diameter and Machine Screw Size Chart — Type a screw number such as #6 or a fraction such as 1/4 to get its diameter in inches and mm, the coarse and fine thread pitches and the tap drill.
• NPT Tap Drill Chart — Pick a pipe size to get the tap drill, threads per inch and pipe OD, with the hand-tight engagement and pitch diameters.
• Thread Milling Calculator — Enter the thread, the thread mill and the cutting data to get RPM, the programmed feed for the tool centre line and the cutting time.
• Thread Pitch Calculator — Enter a thread like M10x1.5 or 1/2-13 to get its basic pitch and minor diameters, thread depth and the measurement over three wires.