Official Luthiers Forum!

hi

looking for info on what hole spacing you guys use on the bridge

also do you have the holes in the line staggered with the saddle slot (sloping) or parallel with the front of the bridge (straight across)
cheers

Sent from my SM-G960F using Tapatalk

There are many different combinations of string spacing at the nut and bridge. LMI makes a clever plexiglass jig for setting the combination you choose. Or just lay it out by hand. I always make a drawing starting at the nut, inserting the fingerboard with the scale length and fret locations, and reference from the 12th fret to the bridge. I also draw the strings on the drawing to double check everything is right.
Doesn't take long, maybe an hour, then you have a permanent reference sheet for the next build with the same specs.

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Brad Hall
Mystic Dawg Guitars

I use a 2 3/16" string spacing, but that's arbitrary. Many like 2 1/4". The general rule is to make the string spacing the width of the FB at the 12th (or is it 14th) fret.

I use the stewmac nut spacing jig, and align my pins parallel to the saddle...

As Brad said. But similar to Ed, my always end up close to 2-3/16". As in 2-1/8" - 2-5/16"

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Joe Beaver
Maker of Sawdust

For what it is worth, here are the spacing choices Martin gave customers in their 2006 Custom Shop Catalog

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Joe Beaver
Maker of Sawdust

I only recently caught onto the rule that the outside pins should be the same distance apart as the width of the fingerboard at the 12th fret. This seems to give the best alignment of the strings to the edge of the fingerboard. I too space them using the same ruler used for doing nut slots. The question of whether the line should be parallel with the saddle, or perpendicular to the centreline, or a curve, or something else - it really depends on the aesthetics of your design. I have seen an argument that a straight line exactly aligned with the grain of the wood means that the bridge is more prone to splitting along the grain at some future time (think of the 6 pins as wedges trying to split the bridge when you push them in). Occasionally you do see bridge splits like that, but I don’t think it is a common enough problem to dictate your method.

Good points Mark. I use to pick nice, straight grain, quartersawn wood for bridges. After thinking about it I came to the conclusion that the bridge would be more likely to spit at the saddle than it would be if the wood had been riftsawn, and the grain didn't align with the saddle

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Joe Beaver
Maker of Sawdust

I also select my bridge stock to be rift sawn.

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Steve Smith
"Music is what feelings sound like"

When I lay out the pin spacing at the bridge, I set a straightedge the distance from the edge of the fretboard I want the strings to be -usually 1/8".
Where it lands on the bridge is what the spacing is.... whatever that number is -

It is what it is.....

Similar to Brad, straight edge, 3 mm inset at nut, 4 mm at 12th, it is what it is.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

For the OM and the dreadnaughts of the 1930's, the 12th fret width was 1/16" narrower than the pin width (1-3/4" nut, 2-1/4" 12th, 2-5/16" pins), and that seems to have given a generous amount of string set-back at the body fret when using a 1-3/4" nut. When Martin shrank the nut width to 1-11/16" in mid-1939, they also shrank the 12th fret and pin spacing to 2-1/8", and used that going forward, which seems to be where the matchie-matchie rule on 12th fret and pin width comes from.

The rule discussed seems like a reasonable approach to ensuring that 12th fret and pin spacing widths are not too far out of whack, but ignores the contribution of nut width to the equation. An alternate rule would be to choose nut width, then set 12th fret width not less than 7/16" nor more than 1/2" wider than nut width, and pin width within 1/16" of 12th fret width. A few other ideas:

- Drawing things out full-size before committing to a non-standard set of nut/12th/pin dimensions should be considered, or better yet, copy the layout of an instrument that works for the customer

- Keep in mind that over-beveled fret edges or notched binding seen on some Gibsons may shrink the usable fret width quite a bit, so consider the player's preferences in fretwork before assuming that a layout will be adequate

We are much more concerned with adequate strength in the saddle slot and moderate break angles at the saddle than with whether the pin line is aligned with the saddle. Mr. Carruth has demonstrated that there are a large acceptable range of string break angles (certainly between 15 degrees and 50 or more degrees), and custom guitar builders employ enough 'smiley face' pin shape variations to suggest that what matters is reasonable break angles and a structurally adequate saddle slot.

A few more things to worry about on overall bridge layout:

- Avoid crowding the saddle with the pins...this can generate very steep break angles, which - while acoustically not of significant impact based on Mr. Carruth's work mentioned above - will increase the horizontal loading on the saddle and may contribute to an eventual failure of the front edge of the saddle slot. Angled/rearward-leaning saddle slots will reduce this horizontal load at the slight cost of accommodating the shift in actual string intonation points when positioning the bridge and when raising or lowering the saddle for action adjustments.

- Avoid placing the saddle slot too close to the front edge of the bridge. The combination of a saddle set just 1/10" back from the bridge forward edge and very closely set pins generating very steep break angles on a relatively tall saddle cost one of our customers more than $500 to address those issues on a nearly new custom-built instrument. As the boss says, it's worth spending some time repairing instruments to see what does and does not work, and worth building instruments to understand the design and construction trade-offs which builders must address (and which keep repair shops in business).

- String-to-string spacing may be done center-to-center or edge-to-edge...both approaches have their adherents, but keep in mind that with proportional/edge-to-edge spacing, the neck center-line will be slightly offset towards the A pin, and that must be addressed when aligning the bridge for glue-up.

- For those that want some additional string set-back on the trebles, a proportionally-drilled bridge may be aligned with the neck center-line passing through the midpoint of the space between D and G pins to give an additional 0.020" or so setback on E4 at the body fret

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For the times they are a changin'

- Bob Dylan

I've started drawing my layout as I start the fretboard and neck builds. I take into consideration the style of playing (finger style will get a little more spacing at the saddle). That said, 2 1/4" is where most end up now that I have fretboard templates built up. 2 5/16" if finger style. The nut width does play a part as Woodie pointed out. My latest commission the guy wanted a wider nut than I usually do 1 7/8" (he has huge hands), so I did a full layout for him as I started into his build.

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Tony Thatcher
Bozeman, Montana