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Matt Clara
10-15-2009, 04:45 AM
At the risk of exciting Chuck into posting another "It's Not Rocket Science Thread", I've decided to go ahead and ask this simple question about bridge placement before I glue mine on this weekend anyway. I've heard several times the distance from the nut to the twelfth fret should be the same as the distance of the bridge to the twelfth fret. I am assuming that people actually mean the word "saddle" where they say "bridge". In other words, I'm assuming the distance from the twelfth fret to the saddle needs to equal that of the twelfth to the nut. Is that correct?

Does this rule of thumb work for any sized uke? Soprano, Concert, Tenor--all the same?

vahn
10-15-2009, 05:16 AM
I remember reading on here that some luthiers also add a very small amount of distance (not sure the figure but possibly an 1/8") extra to compensate for string tension. Someone knowledgeable please correct me here.

Haha, found it (a thread u started btw)
I don't need to think about it. There are lots of examples of compensated nuts with plenty of data to support it. There are also a fair amount of patents related to different processes in achieving compensating the nut. Generally, you wont notice it as much on shorter scale instruments as you will on longer.

Think about it this way, the middle of the scale is at the 12th fret. If you intonate your instrument using the 12th fret harmonic, not fretting at the twelfth then the open string will be "in tune." When you fret it at the 12th fret the distance the string travels to touch the fret makes it sharp. Once you start up the neck or down the neck then it begins to get sharper. By the time you get to the first or 24th fret, you are probaly a couple cents of in tuning. So, if you compensate both the nut and saddle to allow for the changes then it will ideally fret perfectly as well as be perfect when plucked unfretted. So, lets say that you need to compensate 1/8" to get the intonation right. If the bridge and frets are set properly is set in the correct spot then you can compensate the bridge and nut 1/16" and it will play in perfect tune. Make sense?

Matt Clara
10-15-2009, 05:31 AM
Thanks Vahn, but it doesn't answer the essence of my question, which is: am I measuring from the twelfth fret to the front of the bridge or to the saddle itself?

thomas
10-15-2009, 05:40 AM
Measure to the front of the saddle.

And adding some compensation is good. I add 3/32 to my tenors, but that is just me.

Sigmund
10-15-2009, 06:44 AM
There are jigs available - or you could easily build one - that sit on the 12 the fret and can be adjusted to just touch the nut. If you then turn the jig around it will mark the location where the saddle should ultimately sit - any desired compensation should be added to this location. This saves measuring and trying to read a ruler to the nearest 1/64th of an inch. Those of us with presbyopia like such tactile assistance.

ukantor
10-15-2009, 06:55 AM
We are talking about string length. The bridge is just a base to locate the saddle, and it can vary in size and shape. Place the bridge where it puts the saddle in the position it needs to be.

Ukantor.

Matt Clara
10-15-2009, 07:24 AM
We are talking about string length. The bridge is just a base to locate the saddle, and it can vary in size and shape. Place the bridge where it puts the saddle in the position it needs to be.

Ukantor.

So, one could say, the length of the strings should be divided evenly between nut and saddle by the twelfth fret. Unless you want to compensate.
Thanks, I'll stick with that.

thistle3585
10-15-2009, 07:42 AM
One of the "gadgets" I've been wanting to build but haven't had time is a removable tailpiece that would hold the strings while they are brought up to tune then you could slide the bridge around to find the best location prior to gluing it down. Kind of like a floating bridge system on archtops. I was thinking of using a violin chinrest bracket as the temporary tailpiece.

On sopranos, I have been using and 1/8" saddle and locate the saddle 1/16" longer than the scale and then intonate the saddle as necessary. I tend to use lower action than what i see on most ukes but may need to reexamine that due to string buzz. One of these days I need to start a thread to ask about setup including action and neck relief. Look up the "saddlematic" at StewMac to help you with determining the location.

WhenDogsSing
10-15-2009, 07:50 AM
I wish you the best regarding the placement of your bridge/saddle. I build cigar box ukuleles and use a floating bridge/saddle arrangement similar to that used on archtop guitars. The bridge isn't glued down which allows for precise locating of the saddle after stringing the instrument. I guess that there is some loss in volume by using this type of bridge but that isn't as important to me as having excellent intonation. I've been obsessive compulsive about maximizing the string angle over the saddle in the past but on my last CBU, I used the floating bridge setup and am very pleasantly surprised at how much sound it has with a relatively slight string angle over the saddle...:D

Moore Bettah Ukuleles
10-15-2009, 07:53 AM
Matt, I only started that "Rocket Science" thread because some people here have lost sight of what we are doing here, building musical instruments, and tend to get caught up in having the biggest, best and most expensive tools, gadgets and gizmos to do the job. While I believe there is no one best way to do something and no real rules concerning the actual construction of a ukulele there are a couple of hard and fast rules that are indeed written in stone. These have to do with mathematics and physics and are indisputable. One of them is scale length and I think you got the answer you are looking for in the previous posts.
BTW, when considering intonation you also have to take action (string height) into account. Once you build a ukulele that intonates to your satisfaction make a jig for future bridge placements and take the guess work out of it.

ukantor
10-15-2009, 08:04 AM
I don't see the advantage of using a moveable bridge/saddle. It is not difficult to measure the correct location for the bridge/saddle unit, and then glue it in place.

You can never achieve absolutely perfect intonation on a ukulele, or on any fretted instrument. It is all a mass of compromises. It is the player that makes the instrument sound good.

Ukantor.

Matt Clara
10-15-2009, 08:27 AM
Matt, I only started that "Rocket Science" thread because some people here have lost sight of what we are doing here, building musical instruments, and tend to get caught up in having the biggest, best and most expensive tools, gadgets and gizmos to do the job. While I believe there is no one best way to do something and no real rules concerning the actual construction of a ukulele there are a couple of hard and fast rules that are indeed written in stone. These have to do with mathematics and physics and are indisputable. One of them is scale length and I think you got the answer you are looking for in the previous posts.
BTW, when considering intonation you also have to take action (string height) into account. Once you build a ukulele that intonates to your satisfaction make a jig for future bridge placements and take the guess work out of it.

Thanks Chuck--I was tongue in cheek, as your rocket science post came directly after my last post here, but I was pretty sure you weren't directing it at me.

luvzmocha
10-15-2009, 08:29 AM
http://www.ukuleles.com/Technology/compensate.html

I bet he likes Rocket Science!

Pete Howlett
10-15-2009, 08:40 AM
He has a science background...

eleuke
10-15-2009, 05:32 PM
Pete's right. I have David's book. 20 years a research scientist. More formulas than you can shake a stick at... Good book if you're the rocket science type. (Which admittedly, sometimes I am)

Left-Brain Lutherie - Using Physics and Engineering Concepts for Building Guitar Family Instruments: An Introductory Guide to Their Practical Application.

David C. Hurd, Ph.D.
ISBNO-9760883-0-4

luvzmocha
10-15-2009, 06:32 PM
http://www.ukuleles.com/Technology/compensate.html

I bet he likes Rocket Science!

I was being facetious... maybe a bad attempt at some humor.

Coming from an Engineering background I thoroughly enjoyed his book!

ukantor
10-15-2009, 11:40 PM
Musical instruments are not machines, they are an art form.

Ukantor.

Doug W
12-07-2009, 06:26 PM
Greetings,

I need a visual to get this straight. From a drafting background, I like measuring things from center to center but I have found references on the Internet about measuring from the front of the nut, and front of the saddle. Could someone take a look at my link at the bottom of the page under

How do I locate the saddle?...
http://webpages.charter.net/drw46/uke/uke-problems.htm

and tell me if A, B or C is correct or are they all wrong?

Thanks,
Doug

taylordb
12-08-2009, 01:17 AM
Pete's right. I have David's book. 20 years a research scientist. More formulas than you can shake a stick at... Good book if you're the rocket science type. (Which admittedly, sometimes I am)

Left-Brain Lutherie - Using Physics and Engineering Concepts for Building Guitar Family Instruments: An Introductory Guide to Their Practical Application.

David C. Hurd, Ph.D.
ISBNO-9760883-0-4

There is a leftbrainlutherie group on yahoo. I have tried to join it but it says there is no moderator. The group is active as I see there is recent posts in it....just can't read the posts because I am not a member. Anyone know about this group?

Not meaning to highjack this thread.

Dave Higham
12-08-2009, 01:59 AM
tell me if A, B or C is correct or are they all wrong?


Well, none are really right as you've drawn nut, fret and saddle with flat tops. What you should measure is from one point of contact to another and it should look something like this:

http://i967.photobucket.com/albums/ae158/david33_01/Miscellaneous/saddleposition.jpg

When people say the front of the nut they mean the point of contact which should look something like what I've drawn. Although, if there's a slight radius on that front edge, it will push the point of contact back a little. For steel strung instruments the intonation is often fine-tuned by filing the saddle so that the point of contact is nearer or further away from the front edge. You wont often see this on ukuleles but you will see it on guitars.

Intonation is needed because when you press a string down onto a fret you are stretching it slightly. Think about string 'bending' where you push the string sideways to raise the note. The stiffer the string the more intonation is needed, which is why on electric basses with thick steel-cored strings you can have up to 1/2" of intonation!

Hope this helps.

Matt Clara
12-08-2009, 03:31 AM
Greetings,

I need a visual to get this straight. From a drafting background, I like measuring things from center to center but I have found references on the Internet about measuring from the front of the nut, and front of the saddle. Could someone take a look at my link at the bottom of the page under

How do I locate the saddle?...
http://webpages.charter.net/drw46/uke/uke-problems.htm

and tell me if A, B or C is correct or are they all wrong?

Thanks,
Doug

Doug,
You'd probably rather hear from someone else by now, but since no one's chiming in, I'll give you my thoughts on it. Your diagram C makes the most sense to me, except instead of just thinking "edge" of saddle/nut, think of the point the strings come off them as the point you're looking for. With the nut, it is indeed the edge of it. Saddles, however, tend to simply have a rounded top, where the point the strings leave off is really the middle of the saddle. The exception would be where the saddle has been compensated, i.e., filed to have the point of string departure all the way at the back or the front of the saddle. Even then, it's usually just one or two strings that are compensated. My point being, measure from the front of the nut to the twelfth, to the middle of the saddle. On the one concert I've built, I then moved the bridge back 1/16". Sounds great to my untrained ear.

cornfedgroove
12-08-2009, 04:16 AM
face of nut to center of saddle...

face of nut to 12th fret is half scale length
conversely, 12th to center of saddle (or whatever your break point is) is also half scale length.


*my tangent* I gotta comment about chuck's post on people getting caught up in the biggest and baddest yada yada. Its like how some formal musicians playing piano, brass and woodwinds are too "uptown" for guitarist etc. I suppose a better analogy would be comparing people's response to ukulele players as opposed to mainstream guitarists. Since I "only" make cigar box instruments alot of people think they're neat, but dont regard them the same as a "real" instrument. I got half a problem with that...granted, they arent the same as professional instruments, but they are real instruments. They look cool and play well, just like a professional one. I've gotten used to the lackluster response by alot of "fancy" people.

Like Chuck said, it aint about the biggest, best, and fanciest...its about music sucka's! That's why its so easy to tell the REAL music lovers because they think anything that makes music is super cool regardless of how fancy.
Shoot, I think jaw harps are super slick, but...the vibrations hurt my teeth:)

Doug W
12-08-2009, 10:30 AM
Matt,
Join in at any time. My instrument repair knowledge is limited so I welcome any advice. I gave up instrument repair when my son was three. He was watching me work on an old bowl back mandolin that was going to be my introduction into instrument repair. I left the room for something and he picked up a hammer and finished the job.

He's 31 now and I forgave him last month which gave me the courage to start again.

confedgroove,

thanks also for helping to clarify things for me. Think I can get started now.

Regards,
Doug

Dave Higham
12-08-2009, 12:21 PM
Er... I did chime in, but it seems to have gone unnoticed on the previous page. :)

Matt Clara
12-08-2009, 12:45 PM
Er... I did chime in, but it seems to have gone unnoticed on the previous page. :)

It's funny, but your response wasn't there when I posted mine, unless we posted at the same time (roughly).

Great diagram, btw. Here it is again, on this page:

http://i967.photobucket.com/albums/ae158/david33_01/Miscellaneous/saddleposition.jpg

Doug W
12-08-2009, 01:38 PM
Dave,

Sorry for missing your post. Nice drawing. I only read books with pictures and this one says it all.

Thanks,
Doug

Ernie
11-08-2011, 05:28 PM
This is a great thread! Here is a very helpful Fret position calculator... This can be used to determine the compensation for your saddle placement, based on your scale length (I don't pretend to understand how that compensation is calculated):
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CDoQFjAD&url=http%3A%2F%2Fwww.stewmac.com%2Ffreeinfo%2FFret ting%2Fi-fretcalc.html&ei=QvC5Tv_FDoHpggflm_3jCA&usg=AFQjCNH85vfpO6R1gderfhEsUuU3fD7VjA&sig2=fsCQ4ka2CAJWDwZXdSbjJw

joejeweler
11-08-2011, 06:08 PM
It's funny, but your response wasn't there when I posted mine, unless we posted at the same time (roughly).

Great diagram, btw. Here it is again, on this page:

http://i967.photobucket.com/albums/ae158/david33_01/Miscellaneous/saddleposition.jpg

Is this diagram showing 1/16" what most of the builders use as compensation for a soprano scale? The reason i ask is on one of my concerts (prototype) that i removed the plywood top and replaced with a solid spruce top and a new style bridge. i believe i ended up with more like 1/8" compensation using Aquila Nylgut strings.

I will admit i like a healthy string height to allow for clean play and volume at times, so perhaps the extra compensation
is justified in my case. It intonated really nice, btw.

My higher string height and greater string tension of concert over soprano makes sence to me that more compensation is needed. (even more, perhaps, on a tenor?)

Michael Smith
11-08-2011, 09:43 PM
I don't think measuring to the 12th fret than doubling is the best way to go. Every time you measure and mark you will by it's very nature make a small amount of error. Thus using this method your 12th fret error will be doubled as it relates to the other frets. Better to use set all frets and bridge using the stumac or other calculator.

joejeweler
11-08-2011, 10:26 PM
I don't think measuring to the 12th fret than doubling is the best way to go. Every time you measure and mark you will by it's very nature make a small amount of error. Thus using this method your 12th fret error will be doubled as it relates to the other frets. Better to use set all frets and bridge using the stumac or other calculator.

I don't measure from nut front edge to center of 12th fret and double. I measure from nut front edge to the center of the 12th fret, then measure from the center of the 12th fret to the front edge of the saddle slot and add my setback compensation.

.....all done with a 12" thin Starrett steel rule. (careful near the top!)

But then i'm not a builder,....just a home set up my own instruments idiot savant. :D

Michael Smith
11-09-2011, 05:57 AM
My point was saddle placement is more accurate when measured from the nut and not from the 12th fret. As an example lets assume we are adding the same amount of compensation and measuring to the same place on the saddle and from the same place on the nut.

Scale = 300mm
Fret 12 @ 150mm

Fret 6 was to be placed 87.868 mm but as the world is not perfect was placed 1/4mm flat
Fret 12 for the same reason was placed 1/4mm sharp @ 150.25mm

By now measuring off the 12th fret you take the 150.25mm and double to 300.5mm, compensate and place the saddle there.
You now have and error of .75mm @ fret 4. This error could get worse or better when you actually place the saddle.

Making all measurements from the nut in this example you would reduce the error all other things being equal.

joejeweler
11-09-2011, 11:15 AM
My point was saddle placement is more accurate when measured from the nut and not from the 12th fret. As an example lets assume we are adding the same amount of compensation and measuring to the same place on the saddle and from the same place on the nut.

Scale = 300mm
Fret 12 @ 150mm

Fret 6 was to be placed 87.868 mm but as the world is not perfect was placed 1/4mm flat
Fret 12 for the same reason was placed 1/4mm sharp @ 150.25mm

By now measuring off the 12th fret you take the 150.25mm and double to 300.5mm, compensate and place the saddle there.
You now have and error of .75mm @ fret 4. This error could get worse or better when you actually place the saddle.

Making all measurements from the nut in this example you would reduce the error all other things being equal.

You have just burst my bubble, as i had assumed fret placement was correct as far as humanly possible. Large Factories such as Martin and Taylor i'm sure have this down pat. Smaller shops "might" not have a template or fixed setup to cut fret slots and so error on any one batch might creap in and go unnoticed.

......but i see your point, placing the bridge as measured from the nut sort of averages any small (hopefully) errors of any individual fret placement. Were the "12th fret" be seriously misplaced, fretting along the entire scale would sound horrible if the bridge (saddle slot specificially) were placed with "it" as the reference point to measure from.