After setting up the Grainger Guitar Parts routing system and offering up the ferrule block, you’ll likely be looking at something like this:

Don’t worry; you’ll be forgiven for thinking you’ve received the wrong template inserts. They certainly do look too big for ferrule block! They are, in fact, correct.

The important thing to remember here is the required 18mm guide bushing. Grainger’s template system is designed to use an 18mm guide bushing and 10/12mm cutter depending on which part you are fitting. The guitar ferrule blocks require a 10mm cutter. The extra 8mm in diameter added by the guide bushing has to be accounted for, hence the enlarged template inserts.

Have a read through the routing instructions and make sure to do a few test runs before routing your guitar!