I know this isnt the first time someone has done this and Im sure everyone has their own process of doing this, but I thought I would share mine.
I recently finished a house remodel and moved in about a month ago. My girlfriend has been asking me to install this hardware in the kitchen for a while and I finally got around to doing it.
These handles are long and being as long as they are if they are not square with the door they would stand out badly. To combat this I made a simple jig to make sure the holes I drilled were the same each time. I used a piece of plastic filler from storefront metal from my work and cut on of the profiles off:
I then measured where the holes needed to be and figured out where I wanted them in relation to the door. I transferred those numbers onto the plastic piece. I used tape so I could see the marks easier.
A good trick I learned when measuring from a line (not hooked or bumped onto something) is to set the tape on 10 inches and that now becomes your 0 inch mark, so in this case 16 5/16" is 6 5/16". It works good on small things but can run into trouble if you are doing larger measurements and rushing (Ive made the mistake of cutting either too big or too small before
Next I did the same thing for another set of holes on the opposite side of the plastic. I marked each hole with letters so I could easily see what hole to mark and I flipped the letters so I could tell if I was doing something wrong. I know it would have been easier to center the holes on the jig but I had already cit the plastic piece at work so I had to work with what I had:
This picture demonstrates the marking of the holes in relation to an already installed handle. To make each the same I bumped the edge of the template onto the edge of the door and then lined up the bottom of the template to the bottom of the door:
Also before I started to avoid a mess of packaging from the hardware in my kitchen and to speed up the install I took everything out of the packaging and separated it all before I drilled the first hole, it helps a lot to be organized: