So you find yourself in a bit of a fix. You have an old home with a bunch of doors that have a non-standard bore hole measurement. What can you do? Unfortunately, none of the manufacturers these days are making door knobs or levers that will accommodate bore holes of that size.
You Have two options:
1. Buy a door boring kit and rebore your doors.
This is a solution some people shy away from, but it really is the best solution. For under $50 you can buy a door boring kit like the one shown on the right. The kit includes a jig to keep the hole saw drill bit drilling in the correct place and included both sizes of drill bits you need - 2 1/8" (main Bore) and 1" (cross bore). Once your doors are re-bored to standard sizes your options are far and wide for style of knobs and levers that will fit your door. This is the solution we recommend.
2. Modify your existing door bore holes:
A common request we get around our shop is for door knobs or levers made for the small 1-1/2" or 1-5/8" bore hole. Actually, while there are deadbolts available that are made specifically for the smaller bore, today's knob and lever sets are, for the most part, made to fit the standard 2-1/8" door preparation. There are a few exceptions, and we'll discuss those here in a bit, but there are no door knobs or levers made for the 1-5/8" bore. There are, however some hardware sets that will easily work on the smaller door prep with a little help, even though they're not specifically made to fit the smaller bore.
Once you get the sides of the hole filed out enough test fit the outside half of the lockset. If it seems to fit into the bore ok go ahead and install the latch into the edge of the door. You may need to drill the cross bore (hole for the latch) deeper. The latches were designed for use with doors that have a 2 1/8" dia. bore hole. So if yours is much smaller, the cross bore will not be deep enough. Once the latch is in place, go ahead and install the knob and tighten the through bolts and you're done! Really not difficult at all.
Not all doorknob or lever sets are made for the 2-1/8" bore hole. There are some, like the Baldwin Estate Series hardware that use a small 3/4" bore hole. If your bore hole is as small as 3/4", give us a call and we can help you find a lock that will fit your door. Also, Mortise locksets dont really have a bore hole like the tubular sets do. You can recognize a mortise set by the tall faceplate on the edge of the door.
|The cast zinc housing on most popular door hardware, like the Schlage lock here, requires a 2-1/8" bore hole.
|If you have the small bore door preparation the easiest solution is to use a lockset that just has the screw posts like this SureLoc doorknob. Other hardware sets with this type of mounting are Emtek, MaxGrade residential, EZSet residential and Dexter. The bore hole can be trimmed slightly to accept the two threaded posts shown above. (Emtek sets come with a plastic latch alignment piece - this piece would have to be left out for installation on small bore hole).
|To make a little room for the threaded posts for the doorknob mounting I used a round rasp on this wood door. You could also just ream it out with a drill bit or a blade of some kind - jigsaw or sawzall. On a steel door use a round file.
|Once the sides are trimmed a bit with the rasp the lockset slides right in and installs without any problem. Some hardware sets, like the Emtek, have the threaded posts top and bottom instead of on the sides, but its pretty much the same procedure for those.
Please keep in mind that we cannot guarantee fitment on everything. We've heard of all kinds of weird door preps over the years and there is just no way for us to be able to know and see what you have exactly.