Installation Issues – Spindle Hole Sizes

Correct spindle hole size is critical to prevent friction, handle issues, and long-term lock damage

Original HubSpot URL: https://learn.simpled.uk/installation-issues-spindle-hole-sizes

If your lock is difficult to operate, feels tight, or develops issues over time, the cause is often incorrect spindle hole size in the door.

The spindle hole must be wide enough to allow internal components (such as split pins or spindle cups) to move freely.
If the hole is too small, parts will rub against the door, causing wear, misalignment, and failure over time.

Minimum Spindle Hole Sizes (By Model)

Use the table below to confirm the correct hole size:

  • SF / SFS models: minimum 24 mm diameter

    • Extra space is required for the bent split pin

  • EF / DFF / SS / TF models: minimum 18 mm diameter

⚠️ Important: These are minimum sizes. Smaller holes will cause issues.

Common Real-World Issue

Some doors are manufactured with smaller spindle holes than required.

Known example:

  • Certain doors (e.g., Rockdoor) may have holes below 25 mm

  • This is too small for SF / SFS models

Result:

  • The lock may install, but problems will appear over time

Solution:

  • The installer must carefully widen (expand) the spindle hole to the correct diameter

Example: EF Model Issue Explained

For EF models, the spindle hole must be at least 18 mm.


What goes wrong if the hole is too small:

  • The outside spindle receptor cup does not fit properly

  • It rubs against the inside edge of the hole

  • Over time, this friction causes the cup to:

    • Shift position

    • Move out of its correct left/right (arrow) setting

Result:

  • Handle operation becomes inconsistent

  • Lock alignment issues develop

  • Long-term damage may occur

How to Check the Issue

  1. Remove the handle/lock from the door

  2. Measure the diameter of the spindle hole

  3. Compare with the required minimum for your model

Still Having Issues?

If the lock feels tight, misaligned, or inconsistent:

  • Recheck the spindle hole size

  • Inspect for signs of rubbing or friction

  • Contact support with photos of the hole and lock components

This helps identify the issue quickly and avoid repeated installation problems.