Fitting Sealed Tuners

Many guitars – both budget and high end – come with open-geared tuners or closed tuners with bushed posts. There isn’t anything wrong with this and there are plenty of very precise, high quality open-geared tuners. There are also some horrible ones, and replacing them can improve the tuning stability of the guitar considerably.

The guitar under scrutiny here is my ‘Chibson’ LP Thinline. It came with vintage-style 6-a-side closed-back tuners which were a particularly cheap and nasty example of the breed, with wobbly posts and loads of backlash in the gears. They had to go.

The first thing to fix, once the bushes were pressed out, was the position of the holes. The sides of the peghead are curved but the tuners should be in a straight line. They shouldn’t follow the curve of the peghead. It’s hard to see in the picture, but on the Chibson they are all over the place. I think the holes were drilled by eye with no jig used.

To help with this a made up a jig. There is a proper jig available but at the time I didn’t have one. I do now. I marked out the tuner holes and drilled three holes in a scrap piece of mahogany left over from another guitar. Ignore the other random hole. The holes are 5/16″ diameter – the same as the bushes on the new tuners. I use double sided carpet tape to hold the jig in place and drill through with a 5’16” ‘lip and spur’ drill. These cut on the outside of the hole unlike a ‘jobber’ drill which cuts from the middle. This means they will successfully enlarge the existing hole in a slightly different place without ‘falling into’ it.

The new tuners are sealed and have a collar to support the post. Old one on the left, new on the right. You could just drill a big hole all the way through but that would leave the bush at the top flopping about in an oversized hole. The proper way to do it is to drill a stepped hole. In the step above I correctly located the holes and drilled them to 5/16″. Next I take a special reamer with a 5/16″ guide and use it in the pillar drill to open the BACK of the hole out to 10.08mm. This is exactly the right clearance for these sealed tuners.

This is a seriously scary job on a complete guitar. I had to balance the body on my shoulder with the headstock flat on the drill table. One false move and the headstock would have snapped off. Fortunately it didn’t and the stepped holes are visible in the photo. It’s a lot easier to do before the neck is attached.

All that remained to do was to fill the old screw holes, fit the tuners and drill new screw holes. The bushes on these tuners are threaded and lock the tuner securely to the headstock. The screws don’t really do much apart from preventing the tuner from turning.

I’m really impressed with these tuners. They look spot on and they work really smoothly. They aren’t even all that expensive. I will definitely use them again. You can get them here.