How To Fit New Door Knobs & Handles to Old Latches

How to Reuse an Old Tubular Latch with New Door Handles or Door Knobs

If you're renovating your home and replacing your door knobs or door handles, you may want to keep your original internal doors. Many period properties still have their original tubular latches or sash locks, but older hardware was manufactured using imperial measurements rather than today's metric standards.

This means the spindle supplied with your new door furniture may be slightly too large for the existing latch. Fortunately, there are several ways to overcome this without replacing the lock.

Ebonised beehive door knobs fitted to an original tubular latch

Why don't modern spindles fit old latches?
Solutions
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Why don't modern spindles fit old latches?

Many period homes still have their original tubular latches and sash locks. Problems can occur when fitting new door knobs or door handles because the spindle hole is fractionally smaller than today's standard.

Older locks were manufactured using the imperial measurement of 19/64 inch, which converts to approximately 7.6 mm. Modern tubular latches use the industry standard 8 mm square spindle. Although modern spindles are manufactured slightly under 8 mm to allow for tolerance, they are still often too large to pass through older spindle holes.

This small difference is enough to prevent many modern door handles and door knobs from operating correctly with original hardware.

Tubular latch showing spindle hole

Solutions

There are several options if your new spindle doesn't fit your existing latch.

1. Replace the Door

This is the simplest solution, but also the most expensive. If you're restoring an original period door, replacing it is usually undesirable.

2. Source a Smaller Spindle

It may be possible to source an older imperial-sized spindle. However, this often creates another issue because modern door handles and door knobs are designed to fit an 8 mm spindle. A smaller spindle may leave the handles loose or prevent them from operating correctly.

3. File the Spindle to Fit

This is generally the best solution.

Secure the spindle in a vice and carefully reduce its size using a draw file. Removing between 0.5 mm and 1 mm can take a little time, but it allows you to retain the original latch while ensuring the new door furniture fits securely.

Alternatively, you can carefully file the inside edges of the spindle hole within the tubular latch or sash lock instead of modifying the spindle itself.

Using a draw file to reduce the size of a spindle