Bolt Circle & Hole Pattern Coordinate Generator
Hole coordinates for bolt circles, rows and grids with DXF, SVG and G-code export.
Coordinates
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See Bolt Circle & Hole Pattern Coordinate Generator in action
Free Bolt Circle & Hole Pattern Coordinate Generator
A bolt circle is a set of equally spaced holes on a circle — wheel hubs, flanges, pulleys, motor mounts. Enter the number of holes, the bolt-circle (pitch circle) diameter, a start angle and the centre, and the generator returns the exact X/Y coordinates and angle of every hole, the chord distance between neighbouring holes and the across-holes distance used for inspection. Presets fill common wheel patterns such as 5×114.3, 5×100, 4×100, 6×139.7 and the NEMA 17 4×31 mount.
Linear rows and rectangular grids (with rotation and optional centring) are covered too. A live preview draws the holes and the pitch circle; the coordinates can be copied as CSV, downloaded as a DXF or SVG with circles of your hole diameter, or exported as G-code with a G81 canned drilling cycle with your depth, feed and safe height — ready for a CNC mill or drill press with DRO.
Use it in 4 steps
Choose bolt circle, row or grid.
Enter count, diameters or spacings.
Check the preview and coordinates.
Download DXF/SVG, copy CSV or export the drilling G-code.
Key features
Bolt circles with presets
Any count, PCD, start angle and centre; common wheel and flange patterns.
Rows and grids
Linear spacing, grid spacing and rotation.
Inspection data
Chord between holes and across-holes dimensions.
DXF, SVG, CSV, G-code
G81 drill cycle with depth, feed and safe Z.
A real example, step by step
6 holes on a 100 mm PCD starting at 0°: holes at (50, 0), (25, 43.301), (−25, 43.301), (−50, 0), (−25, −43.301), (25, −43.301); chord between holes 50 mm; across holes 100 mm.
Who uses this tool
Machinists and CNC users
Drilling coordinates and a ready G81 program.
CAD users
Check a bolt circle against calculated coordinates.
Makers
Design flanges and mounts accurately.
Tips for the best results
- Use the across-holes measurement to verify a drilled circle.
- For even hole counts measure opposite holes; for odd counts use the chord.
- Use a DXF import to place holes in CAD at exact positions.
- Check the G-code on your machine's dry-run before cutting.
Common mistakes to avoid
- Mixing up PCD and hole-circle radius.
- Forgetting the start angle on a flange with a keyed position.
- Running generated G-code without checking depth and safe Z.
Frequently asked questions
What is PCD?
Pitch circle diameter: the diameter of the circle through the hole centres.
How is chord length calculated?
2 × R × sin(π / N) for N holes on a circle of radius R.
Is the G-code universal?
It uses standard G81 for Fanuc-like controllers (also GRBL variants with canned cycles).
Can I rotate a grid?
Yes — set the pattern rotation angle.
Free, fast and private by design
No signup, no watermark. New AZRS tools are added every week.
