First I cut the bridge blank to size. I used standard Martin belly bridge dimensions I procured from the Stew Mac web site.
Then I marked the center of the bridge and the locations of the two E strings. I am using 2.25" spacing on this guitar. Once I had those measurements established, I used my string spacing ruler to lay out the locations of the remaining strings. I don't think it would make any difference if I simply made each string equally spaced but I have the ruler, so why not use it?
I then used my drill press to drill the holes for the strings through the back edge of the bridge. Be sure to note the extensive clamping I used to avoid the bridge moving around during drilling. Oh...there are no clamps in this pic? Well I used my right hand during the actual drilling. This pic is staged. I used a 5/64" bit for these holes. I determined this was a good size by guessing. Or by drilling a hole in scrap. I'm not telling.
After drilling the holes, I used a 7/32" bit to countersink the holes. I put tape on the drill bit to keep it from going too deep. I tried to make the countersinks deep enough to almost completely cover the ball ends. I didn't want to go too deep and risk compromising the strength of the back of the bridge.
I wanted to have about .25" of wood from the back of the bridge to the beginning of the slot where the strings start to go up to the bridge. It seemed to me that the saddle would raise the strings up sufficiently that I need not worry about the angle of the ramp in the string slot area. I used the set up in the next pic to slot the bridge and also to cut the slot for the string access.
I wound up with the mess below after cutting the two slots. Once the slot in the back of the bridge was cut, I used a chisel and a dremel with various attachments to cut the ramp.
The curved lines are where I would shape the wings. I used a very precise method for establishing the curves, namely a roll of blue painters tape because the radius was the right size out of all the things laying on my bench at the time.
True story.
I wasn't worried that the slot in the back of the bridge was sloppy. I was going to hack away at it with various sharp and pointy things anyway. After a bunch of sanding, chiseling and a quick wipe with Danish Oil, here is what the bridge looks like:
There you have it. I pretty much made this up as I went along. I had three bridge blanks to work with if I messed up the first, but it all worked out. I had a vision in my head of what I wanted the finished product look like and I figured out as I went along how to get there.
If I missed anything that might need filling in, I will do my best to explain but these are all the pics I took of the process. Well...except for this one:
but it shows less detail than this one:
so I went with #2.
Thanks for looking!
Tony