I have put together a number of Warmoth six-string guitars, but I am working on a first bass - Warmoth neck, Ebay body. The body wood is decent enough, but I just realized there's no hole for an under-bridge ground wire to the control cavity. It's standard P-bass dimensions. As best I can see, Warmoth seems to drill a hole straight down from the bridge, then intersects it with another across from the control cavity? The bridge base plate is a full 2" from the corner of the cavity and 3.5" from the pickup hole, it would take an even much longer bit to get there in one shot. What's the customary plan for bridge grounding on a passive-wired bass?

Not knowing what type of system your installing I would say don't drill it unless you have to. But if you must they sell 13"x 3/16" bits.

most all systems want you to ground the strings at the bridge... I always drill my hole from the neck pocket using an "aircraft drill bit"... it's about 18" long or so, and allows me to drill a straight hole and then just drill a small hole or route straight down on the body to intersect it. I then run the ground wire from the bridge, through the bridge pickup cavity and into the control cavity.

I have cheated and used a side-mounted jack on most everything I built that was not simply top-routed.

Then, you can just turn the bass on it's side and drill straight through the hole for the jack right to the baseplate for the bridge, straight shot!

I usually mount my jacks too far on the butt-end to make that practical... hence the long freakin' drill bit ;)

I use a workflow similar to Warmoth - I route a small dimple with a 1/2"D flush bit, and then use a l-o-n-g 3/16" drill bit at a very shallow angle to connect to the control cavity

you can see the dimple and drill bit here
http://i21.photobucket.com/albums/b253/Rodent65/Basses/MiscProjects/51TeleP/Tele5P_1Y_BodyCavitiesRoutedRe.jpg

the dimple is about as deep as the grounding wire diameter, and it has just enough edge to hold the drill bit so it can bite in without skipping all over the place. (the dot seen in the center of the dimple was for another purpose unrelated to the grounding tunnel)

all the best,

R

With a sharp bit it's not difficult to drill at an angle, although Rodent's example is at least as long as any I've done. You can also start your hole straight down for maybe 1/16" and then angle it to make sure your bit doesn't "walk". Practice a couple of times on scrap and check your angle from several perspectives. The angle shot is easier for me than trying to get two holes at right angles to meet perfectly, and getting the wire through is easier as well. Stew Mac has the bits, which I've had trouble finding locally.

my bit (above) was a Home Depot purchase. locally these are a regular stocked item. can't say that I've seen them available at Lowe's though

all the best,

R