So as an IT guy, I often have things that are supposed to follow a standard that was declared and developed by some industry guru group like the IEEE. Unfortunately some "standards" are only standards because of de facto use. This is when taking widget from company A that uses "standard X" and making it work with widget from company B that also uses "standard X" usually ends up in me going nuts.
So what does this have to do with my non-technical evening project tonight? Well apparently back in the day all door knobs used a 2" hole in the door. At some point, some genius decided that that was silly and that we should all use a new 2 3/8" standard.
This is all fine and dandy until I decided to replace all of the inside door knobs in my house. So my house was built in the late '60s or early '70s which means that all of my doors have 2" holes. Of course all of my new hardware expects a 2 3/8" hole. When you think about it, that means that I need to get rid of 3/16" all the way around a hole. Not a lot of material, but not exactly easy to do.
Thankfully I'm not the first person to do this and some genius came up with a jig that allows you to use a hole 2 3/8" hole saw without any material in the center for the centering bit. So in case you need do this in your house... you need one of these. Oh and this jig can also help if you have a new door to put in the hole for the latch too.