www.KitGuitarsForum.com

Here is how I located my bridge.

You've seen the Saddlematic or other bridge locating jigs. I wanted to use something that located the bridge more definitively with compensation included so here is what I did. I used a setup similar to a Saddlematic but I used 3 blocks instead of 2. One block is slotted so it fits over the 12th fret. Here is a picture of the jig laying on the guitar to determine the length from the nut to 12th fret.
The slot in the upper block is centered on the 12th fret. Note the middle block is sitting on the fingerboard. The end block is hanging over the end of the fretboard and is slid along the rod till it is against the end of the fingerboard where the nut is placed. Here is an end view.
Note that the holes for the 1/4" rod are offset in the 2 blocks in the foreground. This works out well for using the jig like I want. Also note the nearest block is overhanging the end of the fretboard. Again, I slid this end block up the rod till it was against the fretboard then I tightened the thumbscrew to hold it in place. So the 3rd block (the end block) is now marking the nut position.

I then removed the jig from the guitar and rotated the 2nd block (the center block) 180 deg around the rod. Then I slid it up against the 3rd block and tightened the thumbscrew. Now both the 3rd and the 2nd blocks are marking the nut position. So it now looks like this.
Also note that since I rotated the 2nd block that the offsets are the same instead of staggered like they were before. You can see that better in this view.
Now I want to add the compensation. I calculated the compensation to the front edge of the saddle at the high E and it was 0.070". So I picked out a few feeler gauges that when stacked added up to 0.070" thickness. Both blocks are marking the nut position so I loosened the 3rd block (the end block) and rotated it 180 deg. I didn't mention this previously but the holes and threading for the thumbscrews go all the way through the block so the thumbscrew can be threaded in from either side. Each time I rotate a block 180 deg, I unscrew the thumbscrew and thread it in from the other side.

Now I slid the 3rd block away from the 2nd block (so only the 2nd block is marking the nut position). I placed the stack of feeler gauges against the 2nd block and slid the 3rd block up against the stack of feeler gauges and tightened the set screw. So now the 2nd block is marking the nut position and the 3rd block is marking the front edge of the saddle slot (in line with the high E). Here is a picture of the blocks with the feeler gauges still in place.

So the 3rd block (the end block) is marking the front edge of the saddle slot after compensation. It's no longer useful to mark the nut position. What would be useful is to mark the front edge of the bridge. So I loosened the 2nd block and slid it down the rod 1/2" or so and placed the bridge against the 2nd block. Then I slid it back up toward the 3rd block till the edge of the 3rd block is aligned with the front edge of the saddle at the high E position. Note: I made the width of the 3rd block the same as my string spacing on the bridge (2 1/8" in this case) so I could easily find the line of the high E string (aligned with the center of the bridge hole). So now the 2nd block marks the front edge of the bridge and the 3rd block marks the front edge of the saddle at the high E position. Here is a pic. Note that the width of the 2nd block is the same as the width of the thick part of the bridge.
Now place the jig on the guitar positioning the slot in the first block on the 12th fret and slide the bridge up against the 2nd block and the bridge is located! You of course have to still worry that the bridge is on the centerline so line up the center E string holes with the 3rd block (remember we made it the same width as the bridge string spacing). Note that because of the offset holes in the blocks the edge of the 2nd block is lower so the front of the bridge rides against this edge. The edge of the 3rd block is higher and sits on top of the bridge.

Here is a closeup of the jig holding the bridge in place. Note that if you drilled the hole squarely through the 2nd block, the bridge will be square to the 12th fret.
I wouldn't take squareness for granted so here is a double-check with a centerline finder to ensure everything is centered, aligned with the neck, and that the bridge is square to the neck. Looks right to me.

Note: I used UHMW for these blocks. It's nice since it's slick and probably wont scratch anything. Aluminum would probably work in that it won't rust and the threads are less likely to strip on the thin side of the block (the side with the shortest distance from the rod hole to the edge of the block). I might see if I can talk my brother into making me a set of blocks from aluminum (he is a machinist).

I wonder if there's anyway that thing could be used on a thickness sander? HHhhmmmm!

PS - I just realized I'm dizzy from all that turning around:)

Your tool looks pretty cool but it seems like a ruler and the nice centerline finder you have with the bridge attachment might get you there as well.

John, it would get you there. Unfortunatly, I can't see to read to 1/64" (0.016") so this was more precise for me. For a lot of folks, that's a non-issue.

Darryl Young wrote:John, it would get you there. Unfortunatly, I can't see to read to 1/64" (0.016") so this was more precise for me. For a lot of folks, that's a non-issue.

Yea, I get not being able to see. I have to combine 2X reading glasses with magnifing goggles to do any detailed work. I had a bad lasik eye surgery and one of my eyes sees double. I do not really notice it but fine detail tends to disappear.