Interior Door Knobs - Passageway and Privacy doors

A passage door knob also called passageway door knob is typically used as an interior door knob to open and close a door. While a passage way door knob can be used as an entry door handle, as it does not lock, it is obviously limited in use to doors that open on to secure area such as a walled courtyard or garden

A passage knob set has 2 knobs connected by a metal shaft or spindle that passes through the door and through the latch mechanism inside the door. The spindle is attached to each knob with a small set screw that is screwed into the side of the knob collar. We use an Allen style setscrew which is slightly recessed but effectively flush with the collar and unobtrusive. The spindle is typically an 8mm square rod though some manufacturers use a 7mm rod that they position at 45 degree which is why they are referred to as spindles “on the diamond”. The spindle passes through the door latch though a universal hole that is machined so that it can be used with a square 8mm or 7mm spindle.

 The spindle is one continuous rod for a passage latch but is split into 2 sections for a privacy latch.

How a door knob works with a passageway latch

When a passageway door is closed it is held in place by the tongue of the latch that extends into the strike plate on the door jamb. Turning the knob clockwise or anti-clockwise retracts the latch pulling it out of the strike plate and into face-plate of the door. New doors are usually manufactured with a 2” hole for the latch and a drilled round channel for the latch-tongue. The end of the channel is typically finished with a rectangular cut out which is capped by a metal face-plate that comes with the door latch. If the door is bought with the jamb, then the rectangular hole for the strike plate will also be pre-cut.

A passage way latch has just one functioning cog wheel with flat areas and small 1/16” protruding teeth. Either knob can turn the spindle and in so doing turn the cog to a flat or protruding tooth section. The cog teeth put pressure on the latch and throw it forward into the jamb. In reality the latch sits in a small metal box, and both have springs which make for a smooth action that requires little hand pressure. When the spindle turns the cog to a flat section the pressure on the latch and compressed springs is released and the latch moves back and is retracted.

How a door knob works with a privacy push pin latch

Privacy Interior Knob Set With Push-Pin Style of Lock (zoom to see pin head)

The spindle is now split and there are 2 cogs, one as described above functions to open and close the door by retracting and releasing the spring-loaded latch. The second cog also has a flat perimeter with one recessed section. When the cog is turned to the flat section the pin is pushed forward into back of the latch thereby fixing the tongue in an extended locked position. When the cog is turned to the recessed section, the pin is pulled back and the latch is released. Only the inner knob connects with the pin cog making the lock operative from only the inside. The door can be released either by pulling the pin out or by turning the knob.

There is a small hole in the rose of the outer door knob which can be used in an emergency to release the latch. In this event a small piece of metal can be inserted into the hole to push the pin out thus freeing the knob so that the door can be opened from the outside.

Designing for Function - Part 3 Making A Custom Door Handle

In previous posts we have used a stationary pull to illustrate how a custom piece of door hardware is designed for lost wax casting, but what impact does a functional handle with moving parts have? The answer depends on the function and varies depending on whether the design is for a door- knob or lever and whether it is to be used as an entry door set or as a handle set for an interior passageway or privacy (think bathroom) door.

In this post we will use the set lizard passageway set to answer the question.

The passageway set is made up of several components, some are cast but others are either machined in metal or custom made to order by fastener manufacturers like Seastrom.

While the back-plate is a relatively straightforward piece to cast, the levers (left and right) need to be cast with a square hole for the ferrule and spindle which are the components that connect the levers together and that will connect with the latch that depresses and returns the lever. The 2 patterns, one for each lever, need to be machined for a square hole and how you accomplish this will depend on the medium used for the pattern. A ferrule is then added either to the pattern or to the subsequent wax replica. For bronze castings we machine our own proprietary custom ferrules in stainless steel an alloy that bonds with the molten bronze but as it melts at a much higher temperature than bronze does not distort or melt in the process. For steel castings, as a metal ferule would melt, we incorporate the ferrule into the pattern. The ferrule acts like a sleeve to hold the square 8mm spindle and it is machined with a tolerance that allows the spindle to fit tightly. A “C” spring clip is added under pressure to the outer rim of the ferrule, and this holds the lever to the back-plate.

The lever set must also be designed to function with a tubular latch. The spindle passes through a square hole in the latch, a component made by another manufacturer and that has an internal spring that enables the lever to be depressed to retract the latch tongue and which returns the lever to throw the tongue.

Depending on the weight of the lever, an auxiliary spring can be added to the ferrule to assist the latch and help prevent any sagging. The auxiliary spring is made in spring steel and as part of the design process the back-plate pattern is made with a stop which limits the motion of the spring to a 33 to 45 range.

The mechanical demands and therefore cost to create a new one-of-a-kind piece for a client are inherently expensive.