Gypsy Guitar Action

Bob Holo

Yep, a good topic. Trial and error, theory, it all seems to lead to the same place.

And yes, the action does change 1/2 the distance of the change in the bridge height. (more or less) Since the 12th fret is half way from the nut to the bridge, it is essentially midway through a right triangle... think of taking a piece of string - stretching it between your hands touching both hands to a table. Now raise one end and watch what happens to the center... linear relationship... it's always half as far away from the table as the hand you raise.

Now, in reality, the fretboard isn't exactly straight and it doesn't really point exactly at the bridge foot, and so it's not a perfect triangle, but the concept works. Also, raising action increases pressure on the soundboard which can cause it to deflect more and also can pull up on the end of the neck a bit, so the strength of the soundboard and neck weigh in as you change action... but it's pretty much a 1:2 relationship. Sand carefully, it's easier to sand wood off than it is to sand wood on

pinkgary

So you would sand wood off the bottom of the bridge, as opposed to deepening the grooves the strings sit in? Aren't you in danger of messing up your bridge doing that, if you don't sand it completely flat, or at the same angle it is at the moment? I presume the most important part of the bridge is how it makes contact with the top? Any tips for not cocking that up, when all you have access to is some sandpaper and a cork block!!

BluesBop Harry

You take wood off the top of the bridge the part where the strings sit.
It's all explained in the link i posted earlier

pinkgary

cheers. I got 2 bridges with my Dupont, so i thought i might as well see what it's like with a lower action.

Josh Hegg

You can go too far if you don't mind using shims. : P

Bob Holo

Well... as for off the top or off the bottom, it's a tradeoff. If you take off the top you need to be prepared to re-establish the fretslots, make sure the arch on the top is proper and make sure that you're maintaining the compensation. If you're just taking a little off - this is pretty simple - take a little off the top and then "floss" the string slots with guitar strings so that their depth is ~1/2 the depth of a string and just a tiny little bit larger than the string (so, floss the G slot with a D string etc...) If you're taking a lot off (more than 1mm) then you start to get into making the top of the bridge too thick and potentially changing the string compensation depending on how the bridge is designed (some are linear and the thin part is pretty high - some are twisted or otherwise compensated and get thick quickly) Unless you're "Josh-good" with bridges - don't get into this territory.

If you take from the bottom, you need to be careful not to make the feet too thin or damage any wiring under the bridge (bigtone pickups) and you need to maintain the arch of the feet (to fit the top) and not round the feet (so the bridge rocks) and maintain the co-planar nature of the bridge feet (so the bridge doesn't rock and/or so that the outsides of the feet which are proud of the plane don't dig into the top and cause damage/splits)

Josh goes through a few methods on how to do this (see stickies) the most time-tested is mounting sandpaper to the guitar top... but it's a lot tougher than it sounds and you will likely produce a bridge that rocks. Another method that works pretty well in that it is easier for a novice but not quite as accurate is mounting sandpaper to wood or plastic or something of a consistent thicknesses so that if you lay the sandpaper-covered-wood chunk down on a table and rest one foot of the bridge on the table and one foot on the sandpaper that the foot being sanded is elevated a little and so sanded in a slight angle. Take your bridge off your guitar and set it on a flat table and you'll see light toward the center of the feet... put one end up on something thin and watch that light lessen... typically thicknessess of material from 0.1" to 0.2" will be right depending on how great the arch of the bridge feet. The thing that makes this technique more bullet-proof is that you're sanding the long-way... i.e., you grasp the bridge naturally and move it back and forth like a child playing with a toy car... makes it easier to keep from rocking the bridge while you sand and producing a rounded-foot bridge that rocks and slips around and doesn't make solid contact. When you're using the sandpaper-on-guitar method on a Selmer style guitar with mustaches -you have to scrape the bridge back and forth and it's much easier to unintentionally 'rock' the bridge and produce rounded feet.

And keep in mind - that you might mess it up. Josh now builds instruments and does restoration and setup and etc... but way back in the day - he got his start helping people who messed up their bridges... so don't work on your bridge if it's an original bridge that is part of the collectible value of the guitar and also - don't work on it if you need the guitar to play a gig the next day He's a good resource - if you have a significant bridge problem... IMHO... email him and he'll ask you to take some measurements and he'll fix it - and the cost will be a lot lower than buying a new bridge or the loss of collectible value from hosing an original bridge on a collectible guitar.

OK - well - tomorrow morning i'm back to building and will be pretty scarce till after Djangofest. See you folks there - party on.

jon.hickam

Hello- I am new to the post. I just got a 3 year old Dupont MD-50 appears to never have been played. I am excited to not have to try and get that gypsy sound on my archtop anymore.
I am also having set up issues, fret buzz and an action that is less than a penny at the 12th fret (great tip!). I would prefer a higher action- I am used to playing pretty hard.
How do I get my action higher? Do I need to start with a new bridge blank? Where would I find such a thing?

thanks!!
Jon

BluesBop Harry

Congrats on your new Dupont!

Duponts usually come with two bridges a #1 and a #2, if yours doesn't you can get one here: https://shoppingcart.djangobooks.com/it ... ridge.html