How to Fit Cast Iron Door Knobs

Your Guide to fitting our Cast Iron door knobs

 

Cast iron door knobs are a great choice for adding traditional character to period properties, cottages and country-style interiors. Our Octagonal Cast Iron Door Knobs are inspired by authentic Tudor designs and are available in black and pewter finishes.

Fitting a pair of mortice door knobs is relatively straightforward, but there are a few important details that will help ensure the knobs operate smoothly and do not work loose over time. In this guide, we explain how to fit the latch, mortice bar, rose plates and door knobs correctly.

Tools Required

• Electric drill
• Suitable drill bits
• Flat-head screwdriver
• Allen key
• Tape measure
• Pencil

Choosing a Suitable Door Latch

Before fitting your cast iron door knobs, it is important to choose a suitable tubular latch. Unlike a traditional lever handle, a door knob sits relatively close to the edge of the door. If the latch is too short, your knuckles may catch the door frame whenever you turn the knob.

For this reason, we recommend using a latch that positions the door knob further away from the edge of the door. A 3-inch or 4-inch latch will usually provide a more comfortable amount of clearance, depending on the width and design of the door.

Another important consideration is the strength of the spring inside the latch. Our Octagonal Cast Iron Door Knobs are unsprung, which means they do not contain their own internal return spring. The latch must therefore have a strong enough spring to return the knobs to their original position after use. We recommend fitting them with a suitable heavy-duty tubular latch.

All our cast iron door knob sets are supplied with heavy duty latches, to save you the guesswork of finding a suitable latch! 

How to Fit Cast Iron Door Knobs

 

1. Fit the Chosen Door Latch

Begin by fitting your chosen tubular latch into the edge of the door. Carefully measure and mark the required position before drilling the hole for the latch body and cutting the recess for the faceplate.

Secure the latch faceplate to the edge of the door and check that the spindle opening is correctly aligned with the holes through the door. The latch should sit squarely and operate freely without catching.

2. Pass the Mortice Bar Through the Door

Once the latch has been fitted, pass the square mortice bar through the spindle opening in the latch. Position it so that approximately the same amount of bar projects from each side of the door.

Taking a little time to centre the mortice bar will make it easier to fit both knobs evenly and will ensure that each grub screw has enough bar to grip securely.

3. Fit the Rose Plates

Place one rose plate over each end of the mortice bar and position both plates against the faces of the door. Check that they are level and correctly aligned with one another.

Mark the fixing holes with a pencil and drill small pilot holes for the screws. Take care when positioning the screws so that they do not strike the latch body inside the door.

Secure both rose plates using the fixings provided. Avoid overtightening the screws, as this could pull the plates out of alignment or damage the surface of the door.

4. Screw the Door Knobs Onto the Mortice Bar

Screw one door knob onto each end of the threaded mortice bar. Continue turning the knobs until they sit neatly against the shoulders of the rose plates.

The knobs should sit close enough to the rose plates to prevent excessive movement, but they should not be so tight that they create friction. If either knob feels stiff, unscrew it slightly until both knobs turn smoothly and operate the latch without obstruction.

5. Tighten the Grub Screws

When you are happy with the position of the knobs, tighten the grub screw in each knob using the Allen key provided.

It is very important that each grub screw is tightened against a flat face of the square mortice bar, rather than against one of its corners.

If a grub screw is tightened against a corner, the knob may initially appear to work correctly. However, repeated use can cause the screw to slip off the corner of the bar. This may result in the knob becoming loose, unscrewing or turning without operating the latch.

Before tightening each grub screw, look through the screw opening and rotate the knob or mortice bar if necessary until a flat surface is directly beneath the screw. Tighten it firmly while taking care not to damage the thread.

Incorrect Grub Screw placement:

Correct Grub Screw placement:

Check the Door Knobs

Turn both knobs several times and make sure the latch retracts fully and returns smoothly. Check the operation from both sides of the door and make sure neither knob rubs against its rose plate.

If the movement feels stiff, slightly loosen the relevant knob and test it again. It is also worth checking that the rose plates are aligned and have not been overtightened.

Finally, open and close the door several times to confirm that the latch engages correctly with the keep in the door frame.

Final Tips

• Use a heavy-duty latch with unsprung cast iron door knobs.
• Choose a suitable latch length to provide comfortable knuckle clearance.
• Make sure the mortice bar projects evenly from both sides of the door.
• Drill pilot holes before fitting the rose plate screws.
• Do not overtighten the rose plates against the door.
• Always tighten each grub screw onto a flat face of the square mortice bar.
• Test the knobs from both sides before completing the installation.

 

We hope you found these fitting tips helpful. If you have any questions about fitting our cast iron door knobs or choosing a suitable latch, please leave a comment below or contact our team for advice.