I drilled one of my tuner holes at my parents using the cheapo drill press and a normal drill bit (non Brad point) and one of the holes is visibly off.
The hole diameter is 8.8mm so it’s a bit of pain as you can’t buy a plug size for this.
I have some excess material so would like some help to make a plug so I can redrill . I am not sure the best way of making a plug for such a weird size
Best bet is the lathe. That said it doesn’t look so bad in the photo…!
The 4th hole is about 1mm ish or less off. I think it will make a difference when putting the tuners in as they share screws.
The excess wood is around 19mm thick. Wouldn’t it be hard to turn this, being so thin?
I’d be more concerned about drilling the replacement hole… Given it would more or less overlap with the plug you may run into issues. You might want to consider oversizing the hole and matching the plug size (which would also solve your non-standard size issue).
That said luthiery is not my area of competence, and I don’t know if there would be a side effect of the larger hole/plug.
The next size up I could drill is 3/8" and plug that. Then drill through that.
A metal bushing will be placed into the hole so as long as the bushing covers the hole then the plug will not be seen
I would turn it gluing 3 pieces together first. Maybe cut them with a bigger plug cutter - say 12mm. That way you can turn between centres and cut the outer pieces off afterwards . You don’t want a centre hole left because it won’t be your drill centre and the extra thickness will give plenty of room to turn the plug. Then you might want to use a jig to make sure the new hole is in exactly the right place.
