This is my reference for guitar setups - a Japanese "E-series" Squier Stratocaster from the early '80s. This was an era when Fender-America was not doing their best work, while the Japanese models were superb.
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Here I am getting ready to cut fret slots. I have marked the fret locations along the centerline, just to confirm that everything is right. Below that is my fret slotting guide. It is a 1" piece of aluminum, precisely drilled with a series of holes based on the standard mathematical formula for fret locations, which you can look up, or use one of the online calculators. I made a spreadsheet of it. The holes are numbered along the top, with the corresponding scale length below. The interesting ones are: (rounded-off)
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