Somebody mentioned measuring the hole and then checking the wall chart to see what size drill bit is appropriate... That reminded me of the drill bit calculator we wrote a while ago - measure what you need with your caliper, enter the dimension in the utility and it pops up nearest drill size.
In addition to showing the next larger fractional, letter/number and metric size drill bits corresponding to a decimal value input, plus the next two larger and smaller drills - and the clearance, it now also displays target RPM for a particular drill size,
It defaults to 60 SFPM (a good start for mild steel) and you can tweak the value depending on the material being cut or drilled.
The executable is compressed in "Fractions.zip" and downloadable from Shareware, so if it is helpful to you, send us a couple of bucks.
Eventually I should upload it to the dropbox, but as long as I'm updating occasionally it seems best to keep it on my site.
Carla
Winston Churchill once came to Virginia after WWII to attend the unveiling of a bust honoring him at a local university. At the reception afterwards this well-endowed southern belle pushed her way through the crowd and came up to Churchill, where she told him that she had driven all night over 200 miles to see the unveiling of his bust. Churchill looked down at her chest and then up into her eyes and said "Madam, I would have done the same for you!" No wonder why we love this guy.