Router bushing calculator
ROUTER BUSHING CALCULATOR
This spreadsheet is primarily focused at those woodworkers who design their own router templates. It allows the user to build a library of his/her router bushings to use when designing the templates which can include up to 50 bushings. After the user inputs the bushing information into the list (don't forget to save the spreadsheet so you don't lose the bushing information) he/she simply inputs the bushing number (1 through 50) and the router bit diameter into the cyan colored fields on the spreadsheet. The distance from the guide to the inside and outside of the router bit is then calculated and outputted, both to the output box and to a generic drawing on the spreadsheet. I've started the bushing library on the spreadsheet to include the bushings included with Milescraft bushing/adapter plate set.
I've included another tab in this spreadsheet called "HOLE SPACING." It calculates even hole spacing on your work piece given the length of the piece, the number of holes, and the distance from the ends of the piece the first and last holes are placed.
Note that dimensional information on both sheets can be added as fractions or decimals, however, the spreadsheet will automatically convert decimals to fractions. Both spreadsheets allow you to specify the accuracy of the output, i.e., you can have the results rounded off to the nearest 1/32, 1/64, etc., inch. The default of 1/32 inch should be sufficient for most applications when designing your template. With the hole spacing calculator, you may not need 1/32 inch accuracy and may wish to change this to 1/16.
Use and enjoy this spreadsheet. Should you have any suggestions or detect a bug, drop me a line at firstname.lastname@example.org.