Tools;
A quality drill press
quality drill vice
1/16 drill bit cobalt or titanium tipped will make your job vastly easier
#50 drill bit (buy several)
2-56 tap
Tap handle
white lithium grease
2-56 screws either 5/16 or 3/8 long
PATIENCE!!
I acquired an early 1973 Burgundyglo 4001. This bass was 100 complete except for the huge aftermarket tuners the prior owner put on her. I'm a huge fan of wavey Grover's so I knew I'd have to hunt down a set of proper tuners and ferrules. I got lucky, a FB member from Europe posted a complete set, with screws so I jumped on them.
When they arrived a few of them had some play in the box section. The swedge posts were quite shallow on the loose ones so I knew I'd have to fix them before I would trust them on my bass. I spoke to Paul about providing the instructional video he had made regarding how to drill and tap these. He was unable to get me the video but he told me what diameter screw to use, and I was off to the races.
I had intended to purchase a decent drill press anyway so this project just moved this purchase up a bit. I first purchased a bench mount Ryobi press but returned it after I assembled it and found out it was a piece of junk!! It shook like it had Parkinsons and the chuck wobbled like an old hooker. The amount of runout was unacceptable for any sort of precision work. I then looked at delta pressed, and Jet but settled on a 1/2 hp Shop Fox press.. Man, I'm very happy with this press!! It's built like a tank, had plenty of power, runs smooth, and there is zero runout!!
I purchased the taps and #50 bits on line from the same company but the morons sent me .050 drill bits and not #50!! NOTE: measure and double check everything!! a .050 is no where near a #50 bit. I used 5/16 long 2-56 stainless steel screws.
When I cracked my first Grover open I was stunned at the very small amount of material where the key shaft is. Be precise in center punching this area because if you are off, you will not have the meat to make a strong tapped hole and you will have just smoked a $75. tuner.
Use plenty of cutting oil when drilling. I first used a cobalt 1/16 drill bit to do the lion share of the drilling. The #50 is only slightly larger. make sure you set the depth adjustment on your press since you will need to drill deep into the box back but not punch through the other side. I ended up trashing my first attempt so be sure you have all your ducks in a row before attempting this!! Once again, lots of cutting oil when threading. The material is somewhat soft but it tends to clog the tap pretty quickly. Oil really makes the job go smoothly.
After taping, de grease and get all the metal chips out of the box. The grease in the tuner had the look of bearing grease. I used white lithium grease since I also use it on my M1A1 rifle and I purchased it in bulk. Generously pack the peg gear and the machine head worm gear with grease and reassemble. The beauty of the Grover is that you can assemble them either way for the bass side or the treble side. On some worm gear shafts there is a thrust washer. if the tuner has it, make sure it goes back in. I kept all the tuner parts together to ensure the tuner was put back together with all the parts it originally came with. They are somewhat interchangeable but I noticed a few differences between similar parts.
Each tuner took well over an hour to complete. Probably closer to two hours.
Sepp
