Ahoya,
As requested from a few TBers, I will attempt to explain how I build my bridges. This is my first tutorial, and I am definitely not a pro at building Basses and bridges. My skill will improve just like yours. Here we go.
This is what you will need. Template (or whichever other method you choose to use) bridge blank, extra big, I like to shape the bridge down to final size after the grooves are made, you will also need machine head screws, some springs, a Tap matching the machine heads, and basic tools to work wood and metal.
This is the template, I screw the blank on it, making sure that everything is nice and square. I also screw the template on the workbench to avoid it moving around while working.
Then I put on the template 'top piece'. This part slides over the two edges and has little clearance with the blank. There are two guides on the top piece, which are square, and are as wide as the router base, but the guides are longer than the router base. In my case, the equation is this: Base of router (mm) / by two, - Bit width / 2 + distance you want from the edge of the bridge to the saddle groove. With this Bass, my router is 146mm, bit is 5/8 (16mm) and I needed 3mm between the edge of the bridge and the saddle groove. so... 146 / 2 - 16 / 2 - 3 = 62. so by then you have figured out you place the edge of the blank 62 mm from the Guide (or stopper, on the Base of the template). you still following? Do the same thing for the other side of the bridge, I ended up taking off the bottom stopper and starting the cut from the bottom. Then it is important to screw and draw a line on both the top piece and base (with a ruler lined up with the 'top piece' guide, to make sure it is square too. Then, mark your grooves, according to the string spacing you want.
I took off the top piece and this is what I get. notice how the bottom stopper is gone now, I started the cut from the bottom, through the pine, and ended 3mm from the edge because of the stopper of course.
Holes must be drilled for the machine heads, be sure to leave enough clearance between the threads and the bottom of the saddle groove. Use a fence. In fact use a fence for most of what you do in a shop.
Cut the Brass or Aluminium to make the saddles, this depnds on what kind of Brass you can get your hands on. I use a 'Cremone' which is window hardware, 5/8 wide and 8 mm thick. I cut the saddle grooves to precisely 5mm and the saddles at 10mm which is 15 in total, then I take out about 2mm for the notch (where the strings sit in). so 13mm at the end, that was my desired height for the strings.
Hole for machine head screws are drilled on each saddle.
Holes are tapped, dont forget to order a few, and to use oil, these things can snap if you try tappin a 19mm thick piece of metal. I used 5-40 screws and tap, which is a little big to my liking, but thats what was available.
Then I work the wood to its final shape, I sand it. I do the same for the Brass saddles.
I drill the holes for the anchoring screws, of course with a fence. And check out the string height to see if its ok. Polish the whole thing, Oil the wood or whichever finish you prefer. Dont forget to use CA for those little 1/8 strips of wood between the saddles.
And on that my friends, I wish you luck. Its very important all of these steps are done with a good ruler, and a square, and a fence ! This aint framing for a house, but if you've gone as far as building your own Bass, I figure you are very well aware of this. Peace !
-Mario-
