1964 -D-18 Martin Perfect Bridge Placement

[Rob]

Having nailed down after hours of research that Terry Clements (Lightfoots lead picker) in fact played two 1964 models ,this was the bridge I duplicated after locating a beautiful piece of rosewood. Thanks to Paula at Martin we were able to even detail it had an ivory saddle and to confirm exact specs which she in fact gave me. In reading the book on build a guitar it show bridge placement this way. The luither uses a exact fine mark staright edge from both outer edges 7 frets in from the soundhole to both front finger ends on the bridge.He states they should be identical !( check yours) . Here is something intresting .Martin admits that some mid sixty guitars did NOT intonate perfect . The problem was a worn jig used to set the neck angel and bridge placement. Where would you place the bridge angle wise?
My question before I glue the 3/32" slotted bridge in place using the intonation formula is , to achive 100% perfect intonation should those measurements be 100% to the 64th identical.Why would I ask that you may ask. Looking at tons of what appear tobe perfect square to the picture photos of old Martins and taking exact measuments of these photos some of the guitars definetly have TWO slighty differnt measurments.Going off to check my D-35 Guild just to see how it measures up having a bridge perfect square to the fret board 7 frets in ! - nanccinut

[Ned Knepp]

Bill,
Do you consider the intended string gauge when you set you saddle position or is this a "gross" setting that gets you close enough to mange the string gauge in the final setup?

Ned

[Rob]

Thanks BILL
Big thanks for those measurments as sure they willl come in handy when locating exact spot for perfect intonation
What I mean is the front 90 degree corners of the rosewood bridge to either side of the 7th fret up the soundboard fron the sound hole. Seems to be a slight difference from some pictures that appear ferfect square to the camera.Just wondered if they had incorrect bridge placement square wise to the frets.
My question Bill - What is when you say 25.4 I assume you mean right down the center of the fretboard to the touch point beteen the D & G strings on the saddle. If so what does .4 compute to to the closest 32nd of a inch which is the finest measurment I have? Thaks for giving me a 25 - ?/32 to work with. Rob

[Ned Knepp]

My math is rusty but I think we multiply the denominator of choice (32) times the decimal (0.4) to tell us what 40% (0.4) of 32 equals. When we take 32 X 0.4, we get 12.8 so if we had 32 sticks, 12.8 of them would be equal to 0.4 (40%) of the sticks. That product (12.8) goes over the denominator (32) to make our fraction (12.8/32nds.)

We can't really have a decimal in a fraction so we need to round it off. (in this case, up to 13/32nds. )

If you want to be more accurate, you can multiply the top and bottom numbers by the same number and get a finer graduation of measurement and more accuracy. Say multiply both by 2 and get 25.6/ 64ths or multiply them, by 4 and get 51.2/128ths. We still end up with decimals in the fraction so we still need to round off the numerator, but the rounding error gets smaller and smaller the finer we slice things. ( We need another denominator to get rid of the decimal in the numerator. For instance, 100 on the bottom gives us a fraction of 40/100ths, which may be one of the reasons that machinist rulers often have a scale in 100ths of an inch.) I think this is pretty extreme and that maybe even 64th are too so it would come to 13/32 and be 0.2 32nds too long.

The scale is about 25 13/32nds. (Although I've heard it's better to be slightly flat than sharp.)

Too much information? Sorry. My kids tell me that all the time. (Man, I sure hope this is correct.)

Ned

[Rob]

Hi Bill - Does the nut to cententer 12th fret on high E string and nut to center12th fret then add 3/32 on high - E and lastly 1/8th on low -E bring it all together for two saddle touch points Bill? Just wanted to keep it as simple for anyone trying this bridge placemnt. Thanks also above that we now know yes the bridge is 100%square to the frets even though pics don't look like it. This should get us Sunday afternoon pickers grinning from ear to ear! -nanccinut

[Magnus Hultin]

I have allway thought it must be difficult to position a new bridge with a precut saddle slot.

The bridge will have to cover the footprint of the original bridge and the it seems like a precut saddle slot ends up where it was cut. Especially on a vintage instrument You would like to have the bridge identical to the original in size, shape and position.

For this reason the few bridge replacements I have made have been with bridge blanks. When the bridge is placed i mark out the saddle slot, often using the little Intonator tool available from Stewmac. You want all the release points for each string to fit with some margin inside the width of the saddleslot. I guess with some experience You learn to place the saddleslot by heart, but this experience is yet to learn for me...

[Ron Frazier]

All these measurements have my head swimming!

Start over and make a story pole that is the width of the fingerboard witch will be tapered out of a 1/8 inch Masonite and at the 12th fret cut a hole or slot about 2 inches centered on the 12th fret. At the other end at the bridge make it flat and square with the center of the fingerboard. That will but up to the fount of the bridge, If you measure from the face of the nut to the center of the 12th fret and double the measurement that will be the the center of the saddle + 3/32 . No acoustic guitar will play right on any way . The size of the strings and the height of the strings and the truss rod adjustment will all change the intonation. there are ways to bring it in tune but I don't want to tell you as it will confuse you even more and should not even be tried.

Go make you a jig and use it on any scale by moving it away from the nut or closer.

I set the bridge against the end of the jig and use masking tape under the bridge and mark around the bridge with a sharp knife cutting just through the masking tape then remove the bridge and remove the cut masking tape and that is where the bridge will be glued down.

The story pole that martin is talking about as the story goes some one sabotage it by cutting 1/4 inch of it and no one checked it and a lot of guitars went out wrong. I have reworked several of them.

Ron

[Magnus Hultin]

Ron wrote:
"The story pole that martin is talking about as the story goes some one sabotage it by cutting 1/4 inch of it and no one checked it and a lot of guitars went out wrong. I have reworked several of them."

I have often heard of these Martins from the 60:s and 70:s, and also that the frets were misalligned due to a worn out fretsaw. This would obviousely be a harder job to correct. Others say it was only that the bridge was in the wrong place and the saddle with it.

What is Your experience Ron?

Magnus

[Rob]

On a 64 D-18 Martin ,does anyone know for sure with-in 32nds of a inch what the height is in the middle of the wing?
This is the only measurment Martin never gave me and don't want to bother them a sixth time.-nanccinut