If you were making a radius banjo bridge, and you wanted to make it 5/8" tall, would you make the center 5/8" tall, and thus the outside strings would be less than 5/8" tall.
Or would you measure the 5/8" at the outside strings, thus making the other strings taller than 5/8", with the G string being the highest?
Or is there another way of looking at this?
The 1st @ 5th strings need to be at 5/8, even for smilies.
Bart, banjobridge.com
Edited by - Bart Veerman on 09/28/2024 13:47:28
And when I make a radius bridge I set the apex between the 3 and 4 strings.
Well i'll be ! iam surprised at Barts responce . Iam sure this has worked for him for years . On the other hand i have always made my 5/8ths radiused bridges with the center of bridge at a 5/8ths height (peak) and the outer strings would be about 10-20 thousandths shorter depending on degree of particular radius needed.
Well Red Arrow ...have we 3 bridge makers got you all dialed in now ? Big LOL
Radiused bridges should be the chosen height (5/8, 11/16, etc.) in the center (third string). So the outside strings would be slightly lower. A bridge made the way Bart is saying on a banjo with a heel cut for 5/8 would require the heel to be cut for the different bridge height. (Or I guess you could also adjust the action with the coordinator rods, but that would hurt the tone and response.)
Edited by - banjo1930 on 09/28/2024 14:44:51
Mine have all been cut the specific height at the center.
Ive been making bridges with the height being at the center/3rd string and state that on my ordering page. I came to this conclusion because that's what I measure and confirmed by measuring other radius bridges that I own. This way a 5/8" with a 12,14,16, or zero(flat) radius will measure the same height when measured from the feet to top with calipers. If a customer wanted something different, I'd do the math and translate to what mine are.
i set the 1st string for 5/8 and follow the curve of the fretboard up from there.
It seems we need to first figure out where we're at.
Are we talking about putting these bridges on banjos with a flat, or radiused fret board, cause that's going to enter into the math. A 3rd string 5/8" height will have the outer strings lower, perhaps too low on a flat fret board to the point where strings buzz because of a too-low action.
Mike, you correctly pointed out the 10~20 thou diff between the middle 3rd and outer 1 & 5 string height. At the 12th fret though, that would work out to a 5~10 thou (0.25~0.5 mm) action diff > basically half the height of the thickness of the 1st and 5th string.
For all practical purposes, whichever way, would anyone's fingers really really really notice/feel any difff? Surely not near enough of a diff to warrant a lot of money spent on neckheel angle surgery as that angle is plenty adjustable already anyways.
Keep in mind, I know it all so I'm always right 
Interesting to see there is no unanimous consensus.
My fretboards are radius of 16". When I fit them to the rim, I do so with the outside of the fretboard flush with the height of the head. The same I would with a flat fretboard. With a radius fretboard, that would put the middle of the fretboard higher than the head where the neck meets the rim. So then the need for a radius bridge is in order with the middle of the bridge higher.
So the way I look at it, let's consider the outside of a radius fretboard the same as the outside of a flat fretboard, at least where it hits the rim. Thus, the bridge would need to be 5/8" at the two outside strings. The middle of the radius fretboard would then be higher than the outside strings and thus the bridge would need to be taller in the middle.
To me this all makes sense. And me making a bridge to fit this is not an issue. The issue is how would I describe this bridge to someone. Do we, as bridge makers and banjo luthiers, describe that bridge based on the height of the middle of the bridge or the height of the outside strings?
I've seen bridges for sale that say 5/8" radius bridge, but they never mention what part of the bridge is 5/8".
Seems like I just need to make the bridge as I see fit and name it accordingly. Perhaps "16" radius Bridge, 5/8" on the outside strings". Or "16" radius bridge, 5/8" G String".
Edited by - RedArrowRyan on 09/29/2024 05:15:55
I remember when I needed a radiused bridge a couple of years ago, I was asked to confirm whether I wanted the middle or the outside strings at 5/8. Great service Bart :-)
Wow, memory failure here... I guess I should read my own website every now and then...
I bought a set of radius gauges from Stew Mac for these.
For a 10" radiused fingerboard I use a 12" radius bridge.
For a 12" neck I make a 14" radius bridge.
If I made the 3rd string 5/8 off the head the end strings would be below 5/8.
Hello,
To me, radius bridges built to the radius of the fretboard should never be as out of touch between the Third and two outer strings. Flattening the radius has the outer strings higher than the inner.
Besides, radius fretboards can be compound of at least two radii. The frets are the easiest way to establish a radius. My RB-12 had a 12” radius on the frets. The fretboard was 6” to 9.25” at the 22nd fret.
When I refretted the banjo, used the 9.25” radius across all frets. The 12” with a flat nut allowed the third string to be a jackhammer. I also changed the nut to match the 9.25 radius. This prevented the 3rd string from becoming a jackhammer. Using EVO frets helps also.
Then I request the radius bridge to be the height of the 3rd string at my desired height. I can be assured all strings will be equidistant from the frets. Only when the nut is flat does the outer strings be lower than the third.
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