How to Layout Holes Evenly in Mechanical Designs

Have you ever wondered how to perfectly space holes on a part — whether in a straight line or a circle?

If you're designing flanges, enclosures, or any mechanical part requiring bolt holes or screw placements, this is a crucial step. Inaccurate hole spacing leads to assembly issues, poor aesthetics, and even mechanical failure.

This article breaks down how to lay out holes evenly — with formulas, examples, and engineering tools to simplify your workflow.

Even hole spacing is not just about making parts look good. It's essential for:

- Even load distribution

- Bolt alignment and accurate fit

- Better aesthetics

- Reducing rework or misfits during assembly

Poor hole layout leads to functional issues and higher machining costs — especially in CNC precision parts.

Here are real scenarios where accurate hole layout is essential:

- Designing a motor cover with 6 mounting holes

- Creating a bolt circle pattern for a custom flange

- Laying out screw holes in an electronic enclosure

Each requires mathematical accuracy, not just guesswork.

Want to space 5 holes evenly across a 200mm line?

Formula:  

Spacing = Length / (Number of Holes - 1)

Example:  

- Length = 200mm  

- Holes = 5  

- Spacing = 200 / (5 - 1) = 50mm

Place holes at: 0mm, 50mm, 100mm, 150mm, and 200mm.

Need 6 holes evenly spaced on a 100mm diameter circle?

Formula:  

Angle between holes = 360° / Number of Holes

Example:  

- Diameter = 100mm → Radius = 50mm  

- Angle step = 360° / 6 = 60°  

- Coordinates = (R*cosθ, R*sinθ) where θ = 0°, 60°, 120°…

Tip: Use our free Hole Circle Calculator to get exact coordinates.👇

🎯 Need Help? Try These Free Engineering Tools:

🔗 Hole Circle Calculator
https://www.ekinsun.ltd/tools/hole-circle-calculator

🔗 CNC Drilling Services
https://www.ekinsun.ltd/services/cnc-drilling

🔗 Machining Tolerance Guide
https://www.ekinsun.ltd/blog/cnc-tolerances-explained

🛠 Real Case: Aerospace Mounting Plate

Customer: Aerospace supplier  

Part: Aluminum avionics mounting plate  

Need: 8 M4 threaded holes evenly spaced on a 120mm bolt circle  

Method: Used calculator tool + CNC drilling  

Result:  

✅ Accurate fit  

✅ Passed stress tests  

✅ Saved 20% machining time

Accurate hole layout matters more than you think.

Use formulas or tools to get your layout perfect — whether linear or circular. With precise spacing and tolerances, your designs will assemble flawlessly and cost less to produce.

Want a fast quote with hole layout assistance?  

Use our instant CNC Quote Tool or contact us directly.

📚 Related Reading:

- 👉 CNC Tolerances Explained – [Read More](https://www.ekinsun.ltd/blog/cnc-tolerances-explained)

- 👉 How to Choose the Right Drill Bit – [Read More](https://www.ekinsun.ltd/blog/how-to-choose-drill-bit)

- 👉 Browse All Engineering Articles – [Visit Blog](https://www.ekinsun.ltd/blog)

Need help with layout, drilling, or CNC production?

Our team provides full support — from CAD design to custom machining. Let’s bring your designs to life, precisely.

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