Making a bridge setting jig - good idea or not?

I've been working on a 'contraption' to allow setting the bridge fore and aft, up and down, and side to side. The idea is that once the bridge is properly located, it can be marked and then glued down to the top. For this first prototype test I am using a cigar box uke that I'm making. Hopefully if this works out, the jig will be a little more universal in usage.

So here's my question for you all. Is there something like this already? Is it even necessary? Should I continue on with this project or should I just give up. Bridges have been set since forever, but I will say that after tinkering with setting the various parameters, I felt like it was like, really really in tune.

https://youtu.be/pYoZE4ZUE94

It seems like a bit of overkill if you are only setting bridges on flat top instruments (like a cigar box uke). Stew Mac has a jig for setting bridges on arch top instruments.



https://www.stewmac.com/luthier-tool...gaAlvgEALw_wcB

Len B.
Clearwater, FL

I would think twice before gluing a bridge to the top.

Mandolins typically don't have glued on bridges. Otherwise I don't understand what the jig offers that a ruler and a tuner won't do.

Remember when the humidity changes and the top expands or contracts it changes the string height. Changing the string height changes the intonation. So unless the glued on bridge can easily adjust the height to compensate for weather changes you won't be properly intonated anyway. Also if you change string gauge that also changes intonation. Gluing the bridge on would mean always using the same gauge strings unless of course you are able to change intonation on the glued on bridge.

This bridge and saddle set up is typical for a flat top guitar as well as ukuleles. That is, the bridge is glued to the top, and the only way to intonate is by filing the saddle. So yea, string gauge, weather, etc changes things. One of the things that I was impressed with using this clunky jig is just how in tune I got the instrument. I am however, working on a newer simpler version. Thanks.

To install a new bridge on flat top instruments with fixed bridges, many of us simply locate the bridge, tape or clamp it in place, measure for the saddle position, drill a tiny hole through the bridge near each end of the saddle slot location, insert a couple of tiny nails or pins into the holes, and give the pins a couple of taps so they bite into the top.

The way I do it, I then pull the pins, remove the bridge, cut the saddle slot, put the locating back pins in, apply glue, and clamp. I have two small holes in my clamping caul to accommodate the pins. When the glue is dry, I pull the pins and install the saddle.


If you're using a pre-fab bridge, the bridge position will be determined by the saddle slot that the manufacturer has already cut. Since I make most of my own bridges, I prefer to have the greater flexibility of cutting the slot later. This makes it easier when you are repairing an instrument and there are existing bridge pin holes and the finish line to deal with.

I also use a similar technique to locate a fingerboard. The pins can be installed in a couple of fret slots or inlay cavities.

This is an old technique-- using locating pins for bridges and fingerboards is discussed in Don Teeter's 45 year old book on guitar repair titled "The Acoustic Guitar."
Many factories have been using this technique for quite a while.

The only jigs I need for setting a bridge are the simple interior and exterior clamping cauls. I can even get by without the interior caul, but I use hot hide glue most of the time and it makes it easier to get my clamps set quickly.

I like the idea, but it seems to be geared more towards cigar box, uke, and perhaps a classical guitar style bridge? Guitar bodies would be too large to deal with such a contraption being clamped to the waist. In addition, you have rounded bouts to make clamping more difficult.
Another factor to consider on guitars is the bridge should be parallel to the end of the fingerboard. This is simply visual, but important. I like that you can fine tune the position with threaded bolts, but skewing the bridge would not look right. It's done at the saddle slot.
I like thinking up and building jigs like this. Often, I find they end up too complicated for the job to be done.

All of these points are well taken. I finally came to the point where I needed to make something to see how it would work. I have some new ideas for the next version. I have a feeling I will be tinkering with this for a while. What I like about it was how in tune the instrument was, the ability to raise the bridge, and to be able to play before I committed. I think all of this can be achieved with a simpler method that I'm working on now. Thanks.

I like your ingenuity, how you accounted for all variables! ...Here is a method I used, I believe I saw on YT, possibly from Stew Mac. It probably wouldn't work with the style of Cigar Box uke you are working with here, but you could possible figure out a way to make it work:

I was turning a crummy old classical guitar into a 4 string classical tenor. I changed the scale length so I had to relocate the bridge. I made a clamp-on "tail piece" for the guitar so I could string it up and string pressure held the bridge down. I could slide the bridge forward and back to intonate it. It worked fairly well and the guitar would have intoned well if I had done a better job with Fret placement. But this was a first shot at luthiery so it sits in a closet untouched.

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Originally Posted by soliver

I like your ingenuity, how you accounted for all variables! ...Here is a method I used, I believe I saw on YT, possibly from Stew Mac. It probably wouldn't work with the style of Cigar Box uke you are working with here, but you could possible figure out a way to make it work:

I was turning a crummy old classical guitar into a 4 string classical tenor. I changed the scale length so I had to relocate the bridge. I made a clamp-on "tail piece" for the guitar so I could string it up and string pressure held the bridge down. I could slide the bridge forward and back to intonate it. It worked fairly well and the guitar would have intoned well if I had done a better job with Fret placement. But this was a first shot at luthiery so it sits in a closet untouched.

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The next one I will make (when I get around to it) will actually be based on what you have there (with my own special touches of course :)) Thanks