How To: Fix a Loose Doorknob

Doorknobs can be persnickety things sometimes (yes, I just used the word “persnickety” in a sentence in 2020!). They get a lot of use and can come loose or outright break at times. So, what can you do when your doorknob comes loose? Depending on the type of lock you have there are several ways to fix it and they are all very simple.

There are mainly two different types of hardware on doors that you’ll find today. Most door hardware before WWII was a mortise lock style rather and modern door hardware is typically a tubular lock which was invented by the Chicago Lock Company in 1933.

Diagnosing a lose tubular doorknob versus a loose mortise door knob is a very different thing so I’ll walk you through both below.

How to Fix a Loose Doorknob (Tubular)

There are usually one of two places where a tubular lock doorknob comes loose. The first has to do with the interior screws or bolts.

Issue #1 Interior Bolts

The doorknob screws into the lock (typically from the interior side of the door) with two long screws or bolts. It’s not uncommon for these screws to come loose on well trafficked doors if they weren’t tightened down properly.The first step would be to check these two screws and tighten them down. You want a firm grip but not too tight or they will impair the operation of the lock. Tighten them down using a hand screwdriver to avoid over-tightening.

Issue #2 Loose Lock

The second place that may have come loose is the lock itself. The lock screws into the edge of the door with two short wood screws. If these screws have come loose or stripped out of the wood then the lock itself may be moving within the door causing the looseness. Tighten these back down and use a toothpick in the screw hole if has gotten hollowed out too big to accept the screw. I’ve got a tutorial on how to do this easy trick right here.

If neither of those work then you may have something wrong with the lockset itself that may need repair by a locksmith or it’s also possible the lockset was designed for a thicker door than what you have.

How to Fix a Loose Doorknob (Mortise)

A mortise lock is an entirely different animal than a tubular lock, but its doorknob can come loose in two simple ways as well that I’ll show you how to fix below.

Issue #1 The Set Screw

First is the set screw. A mortise lock contains a doorknob that screws onto a threaded square post most times. It is then held in place with a very small set screw. This set screw on the base of doorknob must be tightened all the way down against the post to keep the doorknob from spinning indiscriminately.

If you are able to turn the doorknob further than normal and it doesn’t seem to be grabbing the lock then a loose or missing set screw is usually the culprit. Turn the doorknob so the set screw in directly above the flat part of the post and tighten it all the way down. It’s difficult to over-tighten this screw.

Once you’ve tightened the screw try to turn the knob a bit. If it loosens then you may have had it misaligned on an edge of the post. Give it another turn about an 1/8″ and try to tighten it down again. This time it should hold.

Issue #2 Loose Post Connection

The post or “spindle” that the doorknob screws onto in a mortise lock is designed so the two doorknobs can be positioned closer or further away from each other. If you pull or push on the doorknob and it seems to have too much play in it then you can resolve that by shortening the distance.

First, loosen the set screw from earlier to allow the doorknob to spin freely. Then turn the doorknob clockwise to tighten it further. Once you have a good distance you can tighten the set screw back down to lock it into position.

If you tighten the doorknob too much then you may have a door that doesn’t operate because the post can’t fully engage the lock. If that is the case back the doorknob off about a half turn and try again until you’re happy with the fit.