Monday, April 13, 2009

Bass Bridge

The bass bridge is yet another story in and of itself. I am using an adjustable bridge, which I greatly prefer. It is easier to set the height, and since the height is adjustable, you can get the "perfect" setup for anyone with the turn of a wheel.

I generally fit the feet of the bridge before I do anything else. With the entire bridge in one piece, it makes it easier to see what angle you are working with. It is also important that the distance on the feet are accurate because you are working with matching the contour of the feet to the contour of the bass body. I generally thin out the feet first, then start the fitting. I like to use sandpaper on top of the bass when I get close to the fit. Carbon paper (or regular paper that a pencil lead has been colored with) can also help you to find high spots in the feet. They can be scraped with a sharp knife.

After I get the feet fitted properly, I mark both sides of the bridge feet with corresponding dots so that I can tell which side of the bridge goes with which foot. This is very important because I'm going to saw off the feet in the next step!

After I saw the feet off, I smooth the ends out with sandpaper, and then I mark an "X" on all ends to find the exact middle where I will need to drill holes. It is important that the hole is dead center and also straight up and down. The holes that are in the main bridge have to be the correct size so that the threads from the wheels will screw in tightly. Choosing the correct drill bit is very important, so you might want to test it out on a piece of scrap wood first! The holes in the feet have to be larger so that the non-threaded end of the wheels fit snugly but not too tight. I use a drill press to drill the holes so that they are perfectly straight up and down.

After I get all the holes drilled and everything is put together, I put the bridge back on the bass to make sure that the fit is still good. The angle of the feet can change a little bit depending upon how straight up and down the holes were drilled. Sometimes a little extra fitting is needed in this step.

I use a straight edge layed directly down the profile of the bridge and a pencil to help mark my initial bridge height. With an adjustable bridge, this does not have to be quite so exact. Then I use a template to mark the curvature of the bridge. Lastly, I cut the bridge height (curvature), and I start to thin, shape and trim the bridge. Once the bridge is complete, I mark the string slots and file them into place with a small, round file.

I can't actually do the final fitting of the bridge until I finish the nut.

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