GraphTech’s InvisoMatch mounting plates are a great way to fit the Ratio tuners without the need for any drilling. 4 sets of these plates are included in each set of machine heads. They allow you to mount the Ratio tuners via the existing machine head’s screw holes rather than the Ratio’s 2-pin configuration. However, the problem with these plates is that they do not account for different headstock hole sizes.
An example would be the PRT-952-213-00 set of plates which are for Gibsons with vintage style machine heads; Kluson style, 3 by 3, two screw mounting configuration. But the issue here is that these tuners will typically use a slim 6mm post with an 8mm press-in bushing. This is smaller than the Ratio’s 10mm size – a standard for most modern style tuners – making these plates and the Ratio tuners unusable.
The solution: you’ll have to open up the headstock holes using a tapered reamer.
This is far from ideal. I image most people choosing to use these plates want to preserve their guitar’s original specification – understandable for more expensive instruments. As of writing this, GraphTech only make these tuners with a 10mm post.
