If your tuner was slightly bigger than 18mm you could use what’s called a reaming tool to enlarge the hole but evenly and not damage the finish. Unlike a drill bit which isn’t the best for that job.
If you can’t find 18mm tuners at your price point, based on the size you find in relation to 18mm , do one or the other. Clear as mud now?
However a reamer or bushings are going to cost you money as well.
Today I spent four hours veneering my 6 string bass. Mr Haynes senior donated a metre of fleeced walnut burl, just enough to cover front and back of the body and headstock. I managed to not ruin anything !
Cause of inability to find neck where shipping isnt more than 3x the price of the neck, I contacted local luthier to see possibilities.
So I’ll be having custom made neck, so I can also put any tuners I like on it.
Will be ordering Licensed Hipshot Ultralites.
It will be a bit more than I hoped but still much less than getting Vintera replacement neck, and I’ll be getting real rosewood. So spec wise I’ll be getting real 70’s replica neck.
Get the USA ones, not the Licensed. Unlike most “Made in USA” products, in this case there’s a huge difference; the USA ones are machined aluminum while the Licensed ones are cast zinc.
Machined aluminum is so vastly much better than cast zinc that I am kind of embarrassed for them that they do this and try to pass it off.