Better Bolt Bridges – Left-handed Thread Rod

Better Bolt Bridges – Left-handed Thread Rod

I had been struggling with keeping my floating bolt bridges in place for proper intonation. I would set the bridge perfectly, as pictured below:

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However, over time, the vibration of the strings would eventually turn the bolt, thus throwing my guitar out of tune, as pictured below:

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If you look at the first picture, you can see that the orientation of the string is strained as it fights to stay in one of the thread slots. The force that the string places on the bolt naturally moves the bolt into a position where the string sits comfortably within a thread slot.

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Even bolt bridges that are mounted into a slot suffer difficulties. However, since the bolt can not turn to orientate the threads with the strings, they are more prone to slipping into another thread slot, which leads to intonation and string spacing problems. Plus, a string sitting on top of threads allows less usable surface area than a string seated within a thread slot.

The solution showed up on my doorstep yesterday morning. I had been trying the figure this out when I recalled that, in my warehouse days, contractors would request left-handed thread rod for certain jobs. I looked around and found 3/8 left-handed steel rod at Fastenal for $26.87, plus shipping, which seems pricey, but I can cut about 36 2″ floating/fixed bridges for $1.08 each.

This is the direct link to the rod that I purchased:   https://www.fastenal.com/products/details/47304

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Here is the result. As you can see in the image below, the floating bolt bridge is once again in tune; however, this time the strings will not cause the bolt to turn because the strings are now seated comfortably within the thread slots.

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Tragedy averted—now I just have to find some left-handed brass rod.

Thanks,

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https://www.junkshopaudio.com

 

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PVC Bamboom Stick

PVC Bamboom Stick

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The handle on Bennet’s Bamboom Stick failed during its first use. Bamboo is strong for its thickness, but, in addition to the handle, the frame cracked in four places, while I was cutting and shaping the instrument. The cracks were easy to fix with glue and clamps, but I’m not sure how it will hold up over time. Surely the handle will hold up with the addition of a dowel, but there was still reason for concern.

This led me to look for a more resilient material. PVC is strong and flexible and easy to manipulate. 1-1/4″ PVC pipe is an excellent size for the body and 1″ is perfect for the handle, as 1″ PVC fits close inside of 1-1/4″ pipe.

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For the handle slot, I made horizontal cuts on the body with a hacksaw and then used a 1-1/8 spade bit to remove most of the material on the front and back of the frame. The rest of the handle slot was shaped with files. I cut the handle from a 1″ piece of PVC; it fit snug within the opening. I also slipped a piece of 1″ wooden dowel into to 1″ PVC to reinforce the handle.

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I cut the pickup hole in the same fashion that I shaped the handle slot. Much like the bamboo version, it allows limited range, but a bit more room to install the piece of angle that would hold the simple tuner and the 1/4″ jack. The wall of the 1-1/4″ PVC was too thick for the nut on the 1/4″ jack to fit, so I filed down the outer side of the frame, around the hole, until installation was possible. Although it appears ugly, I have started using hot glue to strengthen my solder joints; it keeps me from having unexpected delays.

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To create more clearance at the front of the handle, I cut down a 1″ cap and glued it to the front portion of the handle. I filed a small triangular notch into the top of the handle and used a screw to tighten the string down. A binding screw worked well to allow the handle to pivot. I added an eye bolt, bent to an angle, to act as a nut and to set a consistent action. For this PVC version, I decided to use heavier eye bolts than I used on the bamboo version to further strengthen the instrument.

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Because of the limited space, I had to set the piece of angle, then install and solder the jack to the pickup, then install the bent eye bolt, and finally, set the pickup in place. In this PVC version, the JSA Nd144 pickup sat loose in the hole, so I cut and shaped a small piece of 1″ PVC to fill the space. I filed the inner sides of the 1″ piece of PVC until the pickup fit snug. After that, I added the usual simple machine to set the open note/octave.

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I added two 1-1/4 jacks to the top and bottom of the frame and a 1″ cap to the back of the handle. For the bottom, I installed a screw-on rubber bumper so that it doesn’t slide on the floor. Additionally, I left the remaining string intact, since there is no easy way to keep the instrument grounded. The jack is grounded to the bridge eye bolt, so one must simply hold the remaining string against the handle, while playing, to keep a constant ground.

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Just like the bamboo version, there is only one E string, but the instrument has a lot of range. I added a simple tuner so that the player can set the open note/octave. The player controls the pitch by tightening and slacking the string with the handle and there is definitely a learning curve, as the player has to listen for the note correct pitch—I place the difficulty level somewhere between playing slide guitar and trombone.

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It seems important to note that when I tested this instrument the string broke rather than the frame or handle.

Check out this quick and thoroughly awful video:

Thanks,
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