Acoustic Guitar Construction

Hi all. Its time to drill my tuner holes. It seems simple enough but I am getting conflicting coversion numbers from mm to inches. I am building a KMG kit and my tuners are 10mm. I am getting 2 different conversion fractions for 10 mm. One is 3/8 and the other is 13/32. Then on my threaded bushing the measurement is 7.75 mm but again conflicting numbers. One is 5/16 and the other is 19/64. I could experiment but dont want to buy more bits than I have to. Does anyone know what the most accurate fractions would be for my tuners? Now about the process. Assuming that 19/64 is the correct number would i be off base to drill that size hole through the veneer side of the headstock to accommodate the threaded bushing and use a tapered reamer to ream out my tuning machine holes to 10 mm on the back side of the head stock? Any feedback would be much appreciated. Hope everyone has a great labor day weekend. Thankyou. Jon

McMaster Carr has metric drill bits of all sizes

http://www.mcmaster.com/#standard-drill-bits/=ticlkp

10 mm is the one we use -- now if you are asking if you have to put a step in the hole (one size for the machine head and a smaller one for the threaded fastener) well, no. There is one supplier that sells a bit like that for about $85!!! the illustrations are so hokey they'll make you laugh since the premise is virtually impossible to duplicate in the real world. A tool looking for a problem.

Anyway, a nice tight fit is important, use a drill press, drill from the veneer side, use filament strapping tape to secure a backing board to the machine head side, start with a small diameter drill bit and work up to the 10 mm final size.

Thankyou ken. Your input put me on the right track to complete the task. Jon

I use this bit (10 mm, have others for different uses). No steps and get the cleanest holes of any bits i have ever used:

http://www.leevalley.com/US/wood/page.a ... 2240,42247

The lip slices in making super clean edges.

Hi Tim. Thanks for the info. Do you use the 10 mm HSS bradpoint bit? Jon

Jon Heimbruch wrote:Hi Tim. Thanks for the info. Do you use the 10 mm HSS bradpoint bit? Jon

Yes.

Thanks