Replacing Grovers With Six On a Plate Tuners

We recently received a guitar with badly drilled and therefore badly fitted Grover tuners.

In my opinion, Harmony guitars do not look right with Grovers, so I wanted to fill the holes, re-align the holes and re-drill the holes for six on a plate tuners. So, this article shows how to do this operation with parts you may have lying about the shop.

The image below show two things. On the edge closest you can see plugs. The Grover installer drilled hole diameters for which there are not ready made dowel sizes. So I turned exact filling dowels on my lathe. The far edge shows an old Harmony six on a side tuner plate with the gears and posts removed. The plate is installed using the original screw holes. The old tuner plate makes an ideal drill guide.

The image below shows a drill bit test fit. I tested several bits until the plain end fit perfectly into the tuner post hole. The goal is to drill this size hole on on the drill press, then drill the 1/4" hole required for new tuners, also on the drill press.

I will ream the 1/4 inch holes to 21/64 inch on the face side, then install new bushings also using the drill press. A separate article covers that operation.