How do you calculate equally spaced bolt-hole coordinates?
Enter pitch circle diameter, whole hole count, first angle and circle center coordinates. Choose clockwise or counterclockwise order and the zero-angle axis. The worksheet produces one X/Y pair per hole, measured from the stated center and axes, so the coordinate convention stays attached to the result.
Which diameter belongs in a bolt circle calculation?
Pitch circle diameter passes through the hole centers. It differs from hole diameter and outer stock diameter. Enter the hole diameter only for a geometric clear-gap check, and stock diameter for a concentric radial edge check. Neither optional value changes the center-coordinate circle.
What equations give each hole position and chord spacing?
Radius is half the pitch circle diameter. Each angular increment is 360° divided by hole count. X = center X + radius × cos(angle), and Y = center Y + radius × sin(angle). Adjacent chord distance is diameter × sin(pi/count), available when the pattern has at least two holes.
Hole i: angle = start ± i × 360/count; X = center X + radius × cos(angle); Y = center Y + radius × sin(angle); adjacent chord = diameter × sin(pi/count)
What does a four-hole hundred-millimeter pattern show?
With a 100 mm pitch circle, center (0,0), a +X zero axis and counterclockwise order, the centers are (50,0), (0,50), (−50,0) and (0,−50) mm. Adjacent spacing is approximately 70.7107 mm. Moving the center offsets every coordinate without changing that spacing.
How do starting angle and direction change the coordinate list?
Starting angle rotates the first hole from the chosen zero axis. Clockwise order decreases the angle for subsequent holes, while counterclockwise increases it. The printed row angle is normalized from +X, allowing the actual X/Y coordinates to be checked against a drawing independently of the input convention.
What do negative clearance results mean?
Adjacent clear gap is chord spacing minus hole diameter. Radial stock clearance is half of stock diameter minus pitch diameter minus hole diameter, assuming the stock shares the same center. Negative values indicate geometric overlap or an opening beyond the stock edge, not a valid fastening or machining design.
Can you use these results directly as CNC code?
The worksheet supplies coordinates, not executable machine code. Work offsets, tool diameter, depth, feeds, fixture clearance and tolerances are not included. Displayed decimal rounding is not a manufacturing tolerance; verify the pattern against the drawing and the intended machine setup before using it.
Which inputs should you check before using the result?
Keep input measurement units separate from quote, product or output units. Enter paired optional data together, and leave unavailable extras blank. Equally spaced geometric coordinates only, up to 360 holes. These are not machine-ready G-code or a fastening-strength assessment. Confirm datums, rotation and machining tolerances.
| Input | Units | Used when |
|---|---|---|
| Pitch circle diameter | in / mm | all modes |
| Whole equally spaced holes | as labeled | all modes |
| First hole angle in degrees | as labeled | all modes |
| Circle center X | in / mm | all modes |
| Circle center Y | in / mm | all modes |
| Hole diameter for geometric gap check (optional) | in / mm | all modes |
| Outer circular stock diameter (optional) | in / mm | all modes |
| Specified minimum hole-to-stock edge clearance (optional) | in / mm | all modes |
How can you compare and save different scenarios?
Save the calculated result to comparison, change one measured value and calculate another scenario. Copy or share the itemized result, download the input and result worksheet, or print it. Clear changes removes current inputs and results; refreshing starts with blank numeric fields.
Which related tools help with the next step?
Use True Position Calculator and Thread Calculator. Check each tool’s quantities and scope before transferring a result. A measurement or material takeoff is different from a quoted installed project cost.
