A few years ago, a customer called me in a panic. He had a couple of installers working at a Federal building in Washington D.C. and they had a problem. This call was about several sets of period reproduction knobs and escutcheons they had manufactured and the installers had been provided with the wrong knob spindles. Several thousand dollars of hardware and two men were sitting idle. The foundry was on the West Coast; the installation was on the East Coast.
The problem was the mortise locks had not been examined properly. The knob spindles would not fit into the lock hubs. A couple of telephone conversations with the factory and the installers on site solved the problem. A small box of spindles was sent out NEXT DAY AIR, the job was completed. Total cost for the spindles, less than $100. Total cost for two men doing nothing for two days - you figure it out!
Progressive Hardware offers a complete catalog of products, yet we probably spend more time talking to customers about what kind of spindle to use than any other topic. So simple but so complicated. I cannot tell you what knob spindle to use in every lock in the country, but I might be able to help you to know what to look for in order to purchase the correct spindle.
During the last 100 years or so, lock manufacturers have come up with all sorts of ingenious ways to get a doorknob to work their mortised lock. Basically, you put a square rod into a square hole and turn the rod; the latching mechanism retracts and the door can be opened. But it was kind of rough on the fingers trying to turn that rod, so someone put a knob or a lever on the end.
The next question was how do we keep the knob on the spindle? Each lock factory had their favorite methods. The simplest was a square hole knob slipping over a square spindle, held in place with a setscrew.
A more complex method was a knob with a setscrew that when driven into the spindle, caused it to expand and thereby locking the knob in place. Later, as manufacturing methods progressed, the factories learned how to thread the square spindle rod. This allowed the knobs to also be threaded internally and screwed onto the spindle, secured in place with one or two setscrews.
So now we have a lock with a square hub, a square spindle that may or may not be threaded and a knob or lever that may or may not be threaded inside. You probably thought you were finished but it’s not that easy.
The lock manufacturers then learned that if they used a square rod that is 9/32” square (.281”), they could put a 3/8” thread on the four corners. It was easy to put a 3/8” thread inside the doorknobs, so this sounded like a good idea. Well, it seems that Yale Lock decided to use 3/8” -20 threads per inch for their spindles. Sargent Lock decided to use 3/8”-16 threads per inch. Lockwood went ahead and made their spindles 3/8”- 18 threads per inch. Other lock manufacturers picked and choose one of these various threads and of course none of these are inter-changeable.
To make matters worse, some lock makers thought that a 9/32” square spindle was not strong enough so let’s use a 5/16”, or 3/8” or even 1/2” square spindle. Of course when you thread these larger spindles you now have a larger thread size. If you put thread on the corners of a 5/16” square you get 7/16” thread and on a 3/8” square spindle you’ll end up with 1/2” thread.
To make life more miserable, Yale Lock decided that we were not capable of measuring a 9/32” spindle with a ruler. After all 9/32” is .281” which is almost .312”, which is 5/16” and how many of those little lines can you really count on a ruler (Remember that this was a long time ago). So when you looked in an old Yale Lock catalog, the 9/32” square spindles are actually called 5/16” square.
Mortise locks progressed and it was thought that it would be a great idea if the exterior knob could be locked and the interior knob would still operate. This was the birth of the swivel spindle.
Stronger mortise locks designed to withstand high traffic and abusive situations.
This mechanical pushbutton lock is an affordable alternative to electronic keypads, electric strikes, magnetic locks and other storefront door security measures.