Recreating a Legendary Banjo Bridge

March 2010

In the 1960'ies Stu Jamieson and Allan Hjerpe designed and built an unusual banjo bridge for their friend, and legendary folk singer, Pete Seeger. A few months ago my good friend Rik Palieri, who knew Pete Seeger for most of his life, asked me to build him one just like Pete's. I do a lot of custom work on bridges but I felt quite honoured by such a request although when I read the nitty gritty details of what all that was required to to do the job I don't mind admitting I was kinda overwhelmed. Just the math involved, yeah, it sure's been a few years since high school all right...

I've been quite busy with other projects so it took a while longer than originally planned but here are some pictures and comments I took along the way while building this bridge. Click the pics to enlarge them:

circuit board blank Ever since Radio Shack pulled out of Canada you gotta wonder - just where do you get a piece of circuit board and a small bottle of ferric acid these days? Finally tracked it down, it was a bit of a drive but there you go, a piece of board and the witches' brew acid, mean looking stuff. It took about one hour to dissolve the copper off the circuit board.
seeger bridge template Copying and template took for ever, I hadn't used Illustrator for quite some time but I finally manager to get it done. I scaled the templates to end up with a 5/8" string height, printed them out and school-glued them onto the circuit board.
bandsawn seeger bridge components I cut out the pieces on the band saw. I figured it would be a good idea to use an old blade as I didn't want to take the chance of ruining the new blade for just these few cuts. Turned out to be smart thinking - plenty of tiny sparks along while cutting and that's never a good thing when it comes to the life expectancy of a saw blade.
seeger bridge ready for assembly Here's the rough-cut pieces. I cut the "insert slots" on the arms a little longer then needed. The original plans didn't call for it but I thought it might add strength while gluing if I'd use pointy tooth picks as cotter pins to squeeze the legs against the "riser" part of the bridge.

By the way, I streched the original scale drawing to make it come out at a 5/8 inch string height.

seeger bridge ready for gluing Here it is, all tooth-picked together and the whole thing feels pretty strong. All four legs touching a flat surface, a good sign. Better hop on over to the dollar store now and treat these bits and pieces on a tube of the finest epoxy money can buy.
seeger bridge ready for action Waddaya know, the stuff cured just great and the whole bridge feels rock solid. It took a bit of fidgeting to get it into position on the banjo but here's a view back toward the tail piece,
seeger bridge on banjo and here's one facing towards the neck. This particular banjo is a top tension archtop, a real loud-mouth bluegrass jobbie with light gauge strings

The concept of this bridge design is to exite a larger area near the center of the head than is possible with conventional style banjo bridges. The "outrigger" legs make it possible for the head to vibrate more from the center of the head and the "wave" moving outwards towards the edge of the head just like a loud speaker cone. The whole thing comes down to the head transmitting its sound waves more properly and efficiently. Meaning of course, the "outrigger" legs cannot be pointing toward the tail piece as that would defeat the purpose of ths design. As well, most tail pieces would get in the way and it just wouldn't fit.

The hardest part of the whole process was doing up the templates with the graphic arts software. I don't use this package very often and I don't even know what all the features and capabilities are but I managed it eventually.

Cutting the slot in the "foot" part of the bridge with handtools was challeging to put it mildly. I drilled two little holes and "connected" them using files. These little slots are what the tabs on the legs slide into and they should be fairly snug. Not too tight, of course, else there's no room for the epoxy to ooze into and do its bonding thing. I used a clear epoxy, a little too much actually, so it took a bit of cleaning up and dremeling down after it had cured. The tube said it was the 5 minute quick set type, it was the only kind they had. According to the instructions you had to mix it for one minute and I dutyfully counted it down while I was stirring the stuff. Before the minute was over it tuned milky and it became stiff. Note to self: putting the lamp right over it so you can see what you're doing heats up the mix...

While shaping the pieces I used a sanding disk whenever I could and a sanding drum on the drill press. The circuit board sands nicely but the dust is incredibly fine - be sure to wear a proper dust mask because orange boogers look weird and well, that can't be much of a good thing...

Going through an old Frets Magazine article and another one explaining the math took a while as it all was pretty scientifical. It appears that Stu and Allan sure went at it with a heavy duty engineering attitude when they came up with this design - they deserve a lot of credit because the result doesn't quite look like your typical and average banjo bridge.

I had some preconceived notions before digging in - I've built a banjo bridge or two over the years and you get a feeling for what will and what will not works. But - I've had some crazy surprises before so I've also learned to keep an open mind as it seems that banjos have their own way of deciding what kind of bridges they like and don't like.

I had expected this bridge to be too flexible construction wise, especially at the top. I had fully expected the vibrating strings to loose their zip as the also-vibrating bridge top would shock-absorb a lot of the sound. Keep in mind that "standard" circuit board, after the acid eats off the copper cladding, is only 1.4 mm (0.05") thick. Well, the stuff I ended up settling for anyway. Anyhoo, this worked out just fine - nice and solid.

I also didn't have a lot of high hopes when considering sound and tone - I had expected it to have a huge amount of sustain and a soft resophonic, "dobro," kind of tone. Yup, I was in for quite a surprise here too.

String tension definitely needs to be slackened before putting on this bridge as you cannot simply slide it under the strings and tilt it to an upright position. You need to slide it under the strings coming in from the side - a bit at the time, continuously helping the strings move across the top. Quite frankly, it's a bit of a PIA to do but when it's finally in position dragging it to its correct location is like any other bridge, well, sorta - the feet really dig into the head making it hard to get the bridge to move. Yes, loosening the string tension sure helps.

Time to face to music... It sounded like a REAL banjo, nothing like the dobro sound I had expected - a full body tone that reminded me of the bass of my old Stelling. The highs were clean but not as brilliant as on my regular bridge. Over all the tone was pleasant, plenty crisp enough but I can see some folks are going to whine about the sustain. Full bodied Stelling-like sustain is what I'm talking about and, keep in mind, the banjo I put it on is a sparky archtop.

I played some three finger AND some clawhammer stuff and the sound was the same either way. The amount of volume surprised me, just about the same as my killer Archie bridge so that means it's right up there in the capability department. The specs below put the volume just a tad under an average Stelling but right on par with yer typical high octane bluegrass banjo.

Specifications for the final version of this bridge:

  • string height: 5/8" (15.9 mm)
  • string slot spacing: 42 mm
  • circuit board: 1.4 mm (00.5") thick
  • Volume at 1 m - microphone facing banjo: average/peak - 84/95 dBA
  • Volume at 1 m - microphone facing away: average/peak - 81/ 92 dBA
  • weight: 3.5 grams

All in all a darn decent sound and volume wise it was right up there with the best of them. Not my all-time favourite sound/tone/sustain wise, keep in mind that I'm an archtop lover, but it could easily grow on me beyond the shadow of a doubt. I don't mind admitting that the sound/tone totally surprised me. Truth be told, it blew me away - I hadn't expected it to sound this good. I've made a lot of proto type bridges over the years that didn't sound near as good...

A few things to keep in mind:

  • Circuit board becomes razor sharp when nicely sanded - I had to be double sure to round off the edges using sanding paper else, because the stuff is so thin, I can see it slicing its way through the head on short notice.
  • No matter how tight your banjo's head is tensioned - the two riser legs will dig into the head a whole lot deeper than you're used to - just too much tension pressure on the thin material, no way to get around it. Of course, this only only a cosmetic item but you need to be aware of it.
  • If you three-finger pick near the bridge than this bridge is definitely NOT for you - your finger and/or thumb picks are guaranteed to hit the legs. No matter how your straighten and lower the arch of the legs, your picks, especially the thumb pick, will get tangled up in the legs, period.
  • If you don't like enhanced sustain than this bridge is NOT for you.
  • The playable head area for this brige is between the mid point of the head towards the neck (plus the scoop zone if you have one). Again, this will make this design pretty much unusable for three finger style playing as I can't see a proper "Scrugger" wanting to sacrifice half their playing dynamics when they can't pick anywheres near the bridge. I can see Stanley fans rolling their eyes...
  • This bridge would be ideally suited for melody oriented playing styles and of course, clawhammer, especially Pete Seeger style.

I can hear your voices with the questions already:

  • what about using green instead of gray circuit board..?
  • have you tried circuit board leaving the copper cladding on..?
  • how about making the legs longer..?
  • what if you change the [rake] angle of the riser..?
  • shouldn't the riser angle backwards..?

Sorry, dunno folks, I'm not sure if I will be in the mood any time soon to undertake experiments of that nature or to re-invent a pretty decent and succesful design. As is, I've spent a fair bit of time coming up with this "final" version but of course, would you be offering the right kind of retainer...

How soon will I make these bridges available and take orders for them? Probably never. Like I said, cutting the slots with handtools is pretty tricky and investing in a CNC router just for this is simply not an option. Having them made would be pretty cheap if you order 10,000 of them but in the real world that probably means most of them would be sitting in my basement for at least a couple of centuries. It's not impossible but for now I'm sure I can fix you up with one of my other bridges. Tried one of my awesome Archie bridges yet..?

Summing it all up: building this bridge was a real nice project. I thoroughly enjoyed the challenge of having to do things quite differently then when I build my regular bridges. If you ever wondered where Peete Seeger got his incredibly clear and "big" sound/tone - wonder no more, it's because of this bridge.

If you really want to take a crack at building one yourself drop me a line, I can let you have a proper 100% scale line art template for $5 and that'll save a lot a futzen' around trying to come up with the proper dimensions yourself.

Source reference:

  • banjoresearch.com (URL no longer active)
  • Frets Magazine, June 1987 edition
 

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Copyright 2009 Bart Veerman
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