Tools/Methods for Bridge Making/Alteration

JonJon melbourne, australiaProdigy Dupont MD50B, '79 Favino
Hi Guys,

I've decided to start working on my bridges myself, as I'm pretty picky (and fickle) with action, and want to be able to experiment without the 2 hour drive it takes me to get to and back from my luthier's workshop. He's really great, but having watched him working on my bridges these past few years, I think it's something I could - with practice - do myself, and enjoy doing. I'd like to eventually be able to make them from scratch myself, but that's a way off for me yet.

So I've got some cheap blanks to practice on from eBay (will use Dupont once I'm a bit more confident), and was looking for advice on the following:

1) Tools - I'm mostly just using sandpaper right now...what sort of files would I need to do bridge feet and string slots

2) Method - advice on cutting string slots: is it just a cut straight down with a file? I know the "half the width of the string" rule for overshooting that a really bad thing? And any tips regarding intonation when cutting a slot?

Any advice would be much appreciated!

Thanks in advance,



  • edited December 2014 Posts: 2,913
    I've never built one from scratch. I only fitted a few blanks I got from ebay for cheap.
    The ones from ebay, I only sanded the feet to fit to the top and made string slots, pretty much.
    I assume you already got that part, feet fitting, so I wont go on about that.
    I'll put this tip though, I'm not sure if someone mentioned similar thing before, is I painted the feet with the sharpie and sanded the feet until the sharpie was gone from the wood. That's how I new I got the good fit with the soundboard.

    The first time I fit the blank I copied the string placement from my original bridge, just held the two against each other and marked the new one with sharpie. Second time, I put the new bridge in place, put the strings over it and eyeballed the string spacing.
    Then I used a sharp knife to make a small marks on each side of the string.
    The rest of it for string slots was a combination of light knife use and just string tension sitting on top of bridge. It worked out OK and sounded good.
    I did do some light filing from the top of the bridge to make it slightly smaller.
    The feet I didn't wanna shave to lower the action, just fitted to the top.

    To do it from scratch, you don't need many tools. A few chisels and a file set, sand paper and that's about it. My issue is I don't have a working space with a table with the vice. I got everything else though, chisels and a bunch of wood to work with, I'll get to it eventually.
    There's a Gypsy jazz Yahoo group with instructions on making a bridge from scratch. I'll send you a PM with those instructions. Since you need to put in a request to become a member of the group, so it's kind of a private group I don't know if people from there are cool to post material here.
    Every note wants to go somewhere-Kurt Rosenwinkel
  • JonJon melbourne, australiaProdigy Dupont MD50B, '79 Favino
    Posts: 391
    Hey @Buco, thanks so much - please do send those instructions through. Good advice too. Thanks again :)
  • JonJon melbourne, australiaProdigy Dupont MD50B, '79 Favino
    Posts: 391
    Any more comments about tools/technique more than welcome :)
  • edited December 2014 Posts: 2,913
    Check out this thread:
    I started by asking about the difference between DuPont and DellArte bridge but eventually it turned into a DIY and tons of good general info about bridges.
    Lots of good info from very knowledgeable people, I learned a lot and it's still my go to reference.
    Every note wants to go somewhere-Kurt Rosenwinkel
  • One way to get a nice string notch is to use an old set of round woulds of slightly larger diameter and shape the notch once the shallow v is cut.
    The Magic really starts to happen when you can play it with your eyes closed
  • JonJon melbourne, australiaProdigy Dupont MD50B, '79 Favino
    Posts: 391
  • Jeff MooreJeff Moore Minneapolis✭✭✭✭ Lebreton 2
    Posts: 476
    "Overshooting" means that string is lower than the neighbors? To me that's the hardest thing to avoid, but avoid it at all costs cuz it makes it harder to get the right sound moving the pick from one string to the next.
    If your setting up your own bridges, particularly cutting string slots, your working in 3 dimensions. Intonation, height over the fretboard, and how they sit regarding the edges of the neck. You can now get picky about these things and experiment to if your making a few.
    You can also carve out under the bridge to lighten it.
    I use a dremel to cut slots, with a thin blade, and two thicknesses of grinding wheels. Especially with the blade, it takes a very very light touch. The grinding wheels are a of course easier to use as they cut more slowly. I'm not recommending the blade just admitting to it, Its about the thickness of the B string. I roll these wheels a little bit "over the top" rather than making a flat cut. Dont' know if rounded slots matter but it seems nicer for the string to be bending over a "barrel" rather than two hard edges.

    I've made maybe 30 bridges from scratch. I'm just following my own methods. Helps to have a couple simple wooden clamps for all of the above, as getting the light perfect for cutting slots is critical to me. Getting eyes, arms, tools, and the bridge itself in the best alignment for work is easier if you have some mass holding the bridge and you holding the mass (a chunk of wood with smaller peices of wood holding the bridge clamped with wood screws. If your shaping or hollowing out a bridge with larger machines, its a must, but sounds like your buying nearly finished bridges, seating the bridge, and cutting the slots.
    But if the bridge is too tall, you can work in all three dimensions to some extent.
    "We need a radical redistribution of wealth and power" MLK
  • JehuJehu New Zealand✭✭✭
    Posts: 77
    Regarding fitting the bridge, I just thought I'd add a few pics since I've recently been in the position to take a few. Apologies if you're already up on this part of the job; maybe it will be of use to someone else.

    Once you've got the shape of the bridge bottom approximated, this is the basic setup. Pretty straightforward... just a bit of tape and some 80 grit sandpaper.

    Next, you want to mark the bottom, as Buco said. I like pencil for this, as it shines in the light. I like shiny things.

    Now, just put the bridge in position and move it back and forth (toward and away from the neck), carefully at first. Use your thumbs and forefingers, and keep as much of the rest of your hands in contact with the top as possible to avoid rocking the bridge as you move. As you can see, the bottom of this mofo was quite rounded, so fitting the bridge should make a big difference.

    The next challenge is to know when to stop. Common sense would suggest stopping when the entire surface is scored and the pencil marks are gone. As usual, common sense is hogwash. Bear in mind that as you're doing this, you're also changing the action. You probably want to minimise this change... unless you don't, in which case there are better ways of lowering the action.

    My action was already on the low-ish end of where I want it, so I decided on a compromise. This particular bridge had substantial 'duckbilling' (TM) towards the edges. If I were to carry on until the edges were flush, it would take an unacceptable amount of height off the bridge. Contrary to what the Internet might say, those edges probably aren't transmitting a whole lot of vibration. As long as the majority of the weight-bearing contact area is flush, you're in business.

    Finally, for anal-ness sake, you probably want to get rid of those scratches with a bit of 120 grit. You don't want to change the profile of all your hard work, so choose your sanding block carefully (and don't use your finger). I used soft rubber foam.

    It's surprising what a difference a well-fitting bridge makes.

    Rob MacKillopBucorgricejonpowlMisterKevster
  • JonJon melbourne, australiaProdigy Dupont MD50B, '79 Favino
    Posts: 391
  • JehuJehu New Zealand✭✭✭
    Posts: 77
    No problemo, my man. This bridge is garbage, and I will probably make a replacement at some point. Relevant to your first point in the OP, it won't need anything more than saws (tenon/coping), a rasp, and any medium file.
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