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Bass Nut, And Therefore Neck Taper, Design


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Hey bass guys. I'm designing a new bass shape, and now that I'm doing my design in CAD some smaller things are starting to be more manageable and interesting when it comes to design elements. One in particular is string-to-edge-of-fretboard measurements. On a guitar this isn't a HUGE deal, cause the thickest guitar string's radius is minimal when compared to the 1/8" people generally place between the string's center and the edge. Therefore, it really doesn't make a HUGE difference whether you do that 1/8" from the center of the string, or from the edge of the string (therefore making the distances different on the high e and low E strings). However, with bass strings being as big as they are this makes a BIG difference. Let's take a 5-string's low B at .135" and a high G at .045". Making a matching measurement from the centers-to-edge is no longer an options here like it is on a guitar because for instance if we took 1/8" we'd be left with .1025" from the high G to the edge (DOable), and only .0575" (less than a 1/16") from the low B to the edge... you'd knock that over the edge while playing WAY too often. So, we therefore must do different measurements and I'm assuming the best way to approach this is to do an edge-to-edge-of-string measurement. However, what we then end up with is a neck with an asymmetrical taper. Not that that's bad, just curious.

I guess my questions would therefore me:

1) What string/edge measurement do you usually use.

2) How do you design your necks and do these thoughts factor into the decision?

Chris

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Hey bass guys. I'm designing a new bass shape, and now that I'm doing my design in CAD some smaller things are starting to be more manageable and interesting when it comes to design elements. One in particular is string-to-edge-of-fretboard measurements. On a guitar this isn't a HUGE deal, cause the thickest guitar string's radius is minimal when compared to the 1/8" people generally place between the string's center and the edge. Therefore, it really doesn't make a HUGE difference whether you do that 1/8" from the center of the string, or from the edge of the string (therefore making the distances different on the high e and low E strings). However, with bass strings being as big as they are this makes a BIG difference. Let's take a 5-string's low B at .135" and a high G at .045". Making a matching measurement from the centers-to-edge is no longer an options here like it is on a guitar because for instance if we took 1/8" we'd be left with .1025" from the high G to the edge (DOable), and only .0575" (less than a 1/16") from the low B to the edge... you'd knock that over the edge while playing WAY too often. So, we therefore must do different measurements and I'm assuming the best way to approach this is to do an edge-to-edge-of-string measurement. However, what we then end up with is a neck with an asymmetrical taper. Not that that's bad, just curious.

I guess my questions would therefore me:

1) What string/edge measurement do you usually use.

2) How do you design your necks and do these thoughts factor into the decision?

Chris

2.6 mm give or take

I mark the scale (nut - 24th fret - bridge) on a centerline, mark the string spacing at the bridge (including string thickness), mark the string spacing at the nut (including string thickness), and play connect the dots. Add 2.66 to the outside of the outside string and done. Then I get my friend to draw it in cad.... :D

As for the asymmetrical taper I have done it... and it works very well if you don't go overboard. I believe Toone is trying to patent it (don't get me started)

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Oh, that's a flare. That I'm fine to let him patent. What I'm referring to is that if you have the nut laid out to be a finite amount (1/8" lets say) from your outer string, and the strings are significantly different in size... and then have these strings go to a bridge that is centered on the body you will end up with a slightly different angle of taper from nut to bridge on the treble side than on the bass side. That said, I GUESS you could counteract this by mounting the bridge off center? But yeah, this stems from the fact that if you have equal string spacing at the nut on a 5-string bass, but unequal center-to-edge measurements because of string diameters, the center of your 3rd string will be slightly below the centerline of the neck. However, on a centered bass bridge the 3rd string is centered.

Chris

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Another way to look at it would be that if you take a centered nut and made the lowest string's center .125"+half the string's diameter in from the edge, and then did the same with the high string (but with it's corresponding 1/2 diameter) they would have different angles as the headed to the centered, evenly spaced bridge. And since the string-to-edge distance is always constant, this different angle also translates to the edge of the fingerboard.Over a 24 fret distance on the bass in question, that I'm designing, this translates to a little over 1/32" (.034" to be exact) difference in the distance from the fretboard's centerline to it's edge for the bass and treble side. The bass side being the farther obviously. Bass is 34" scale, Warwick bridge spacing, and the "narrow" spacing listed on David King's order form for a 5-string.

If it still sounds like babble let me know and I can take some screen shots from Rhino CAD.

Chris

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Over a 24 fret distance on the bass in question, that I'm designing, this translates to a little over 1/32" (.034" to be exact) difference in the distance from the fretboard's centerline to it's edge for the bass and treble side.

I'm not a bass guy....but that sounds like your centerline is no longer in the center and therefore not technically the centerline any more. If you have equal distances from the string edge to each edge of the fret board and if you have equal distances between the strings - edge to edge as opposed to center to center, then the third string would be nearer the true centerline than the second string, but the fret board would not need to be asymetrical...unless your goal is for an asymetrical fret board.

SR

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It's still a centerline in the sense that it goes from the center of the nut's width to the center of the bridge. Also, of course string 3 is closer to the centerline than string 2? I'm just saying that it's point where it meets the nut isn't ON center. It is still the nearest to center. I think I may need to upload some pictures. Also, the reason to choosing equal distances between centers instead of equal distances between edges of strings is simply than how the bridge is. I figured, "if the bridge has equal distances, perhaps so should the nut?" That said, I still don't think making equal edge-to-edge string spreads is going to fix the issue. Not that it's an actual issue. More a topic of discussion.

I'll get some pics up.

Chris

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Alrighty, here's some pictures. Sorry about the large size, but they're really needed to see the differences.

Ok, so what's we're seeing is the nut spread in photo 1 and the bridge spread in photo 2. It's a 5-string base, and then two outside strings showing the associated taper of the fretboard.

-The green lines represent the path of the strings' centers if you choose to pick a constant distance from edge of fretboard to center of string. You then divide the distance between those two outside strings to find the path of the other 3 strings. The center string in here is the same as the neck's centerline! This choice is problematic in a bass due to the strings' diameters and will lead to too little space on the bass side, and too much space on the treble side.

-The red lines represent the path of the strings' centers in you choose to have a constant distance from the edge of the fretboard to the edge of the string. As you can see, this choice doesn't change the nut width, nor does it make the nut off center. Essentially it just moves the point the highest string hits the nut slightly farther out due to it's thinner diameter. This obviously then changes the placement of the other strings since there's now more space between the outside two strings when you divide out to find the other 3 strings' placement.

At the bridge we can really see how this affects the fretboard width. Although the board won't continue to the bridge obviously, it does help to show the differences caused by keeping a constant space on the outside of the string.

Last point. The reason I don't think edge-to-edge string spacing is going to make a difference is because the inner 3 strings don't make a difference on the fretboard's taper. Whether you do those strings center-to-center or edge-to-edge doesn't matter. To illustrate why, lets take the stewmac fret-rule that you can use to easily find edge-to-edge spreads. The first step is 'mark your two outside strings' center locations on the nut. Then move the rule until those two lines show through the marking holes with the appropriate number of strings between them.' The only important points are those of the outside strings.

bassnut.jpg

bassbridge.jpg

Chris

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Just me thinking, but I think you're way over-thinking this. Yeah, the B string is a whole bunch thicker than the G but if you're setting the spacing from string edge to string edge you're doing it by looks instead of feel. When you fret a string, you're pushing on the center of it and the center of it will contact the fret no matter what size string. Distance between them doesn't matter unless they're generally too close or far for comfort while plucking or picking. I don't know about all bass bridges, but I like the Hipshot A style and that one allows for string spacing adjustment so I assume many others do also.

For reference, I'm very happy with my last two builds and the spacing is as follows:

(4 String, BEAD tuning)

Nut width 1.550

String spacing at nut (centered) .410

Neck width at 12th fret 2.240

String spacing at bridge .715

If you draw that out you'll see that I have a generous amount of room between the string and the edge of the neck. Having some extra room there does not making playing difficult or uncomfortable, but it does allow plenty of room for error and prevents accidentally pulling the strings off the side of the neck. I can't see a reason to minimize the neck width to the point where pulling the strings off would be a concern.

Give it some room to breath, keep it simple and it will work perfectly well.

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........I guess my questions would therefore me:

1) What string/edge measurement do you usually use.

2) How do you design your necks and do these thoughts factor into the decision?

Chris

just as you may be "overthinking" it, I am just as guilty of underthinking it. I don't even measure, I eyeball the distance from string to FB edge. I don't use a consistent string spread at the nut either. Personally,I can have a smaller spacing on the skinny strings than the thick strings due to the way my fingers lie across the neck. Down low, they're pointed at the neck, up high on the thick strings, it's the 'face' of my finger / fingerprint-area thats in play so I need some more room. I space mine accordingly.

#2: when I design a neck, I make a quick mock-up using various sized markers for various sized strings and work out my measurements then.

I'm probably a bad example since each build is done for individual purposes and therefor done an individual way which may or may not be identicle to the previous build. :D

I know thats no help, sorry......

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