Official Luthiers Forum!

I'm about to set my neck angle and bridge etc.
I have installed an "A Frame" bracing system (soundhole brace through upper face brace and let into the headblock). Apart from that it's a sort of standard X brace thing (scalloped)
I've two questions;
What clearance should I have over the bridge once fretted (or unfretted)??... My confusion is because Cumpiano says 1/64" to 1/16" and others here have said an 1/8"

No. 2 Question; How much saddle compensation?
Cumpiano says .15" ,Jim Williams says .11". I have heard of .125"

I would really appreciate your help here.

My guitar has Sitka top, Mah. B&S and neck (bolt on mortice and tenon with barrel bolts) And a sort of spanish heel on the H/Block. The top is around 1/8" thick and thinned around the lower bout edges

Kind Regards and lots of thanks!!

    Confused KiwiCraig

_________________
CRAIG LAWRENCE of AUSTRALIA
_____________________________________________

   What I do is get the line so that I can plan for about 1/8 to 5/32 " of saddle height. I can allways lower the bridge a touch.
    I normally do my location without frets but I want so be clear with frets on about 1/16 5/64 off the top of the bridge at the saddle location.
   Once you are ready to set the bridge and saddle you can adjust the bridge to get the saddle height . This is important as the angle if too low can cause buzzing and too hi can cause too much stress at the bridge .
john hall

On a 24.5" scale length, I suggest a 1/8" saddle compensation.

there was another thread within the past week or so asking the same question, and the answer is still the same. using a predetermined saddle compensation is just an approximation which is fine if you are mass producing guitars in a factory and can't take the time/don't have the skills to do the job properly. on a custom made instrument, and if you want your intonation to be really good, intonate each string, mark your saddle line, cut your slot and then make your compensated saddle based on the intonation information already gained.crazymanmichael38598.0823842593

Thanks for your reply John and Michael and Mr. Brazilwood.
Regards my saddle compensation, my scale is 25.4"

I haven't fretted it yet, as I thought it maybe easier to set the angle now. I have this vision of the fretted fingerboard extension being a real bother if I set it after fretwork. It's my first so I don't know what to expect. Is this a good idea?
I figured I could get the extension/soundboard join a bit better as well.

I'm aiming at a 3/8" bridge and 1/8" saddle hieght, so I,m taking slithers off the heel, , measuring with a straight edge for air space above my imaginary 3/8" bridge. I,m looking for 1/16".. Is that correct?

Does that mean you would expect the string pull to give me a good playing action based on those specs?

John, I think I see the importance of having the right angle down off the saddle. Is 1/8" O.K.?
this is why I'm trying to get it correct now. I have read where 12.5 m.m. to 13 is a real sweet spot for the strings above the soundboard.

My fear is setting the neck angle now , only to find that the guitar didn't behave as expected under tension.Then have to reset again,,,,,,,,or is the done thing?

Michael, I admire your skills, being able to rout the saddle slot after installing the bridge. It would definatly has to be the most accurate, but scares the hell out of me.Or do you put two bolts through the pin holes to temporaraly take the string pull?

Again,, Many many thanks you very clever men . I can't tell you how much I appreciate it.
   This forum is fantastic! and your such great people.

      KiwiCraig

_________________
CRAIG LAWRENCE of AUSTRALIA
_____________________________________________

KiwiCraig...I allow the 1/8" compensation factor for routing the slot for the saddle. Each string can then be individually compensated. Provided you use the correct width saddle blank.

   Martin uses a 3 degree angle. I personally use 3 degree on all my saddle placments. I orignally posted on the height. Gibson used a 4 degree. I found that 3 is about as good as you can get on a standard bridge. If you want to split the saddle it can get very complicated.
   the amout if compensation on a 3 degree is about .125
john

Thanks again guys, That info is all good. I haven't made myself clear enough,,I meant the amount added to the 25.4" scale to be the middle of the saddle slot

My fault, I think I said saddle compensation instead of scale compensation. Compiano says .15" others 1/8"
What's the story?.. I'll fine tune on that but it'll give me a ballpark figure to go on.

Sorry about not making myself clear (An old Kiwi trait)

I,m totally gone on this guitar building thing.Obsession is an understatement.You guys who knock them out one after the other amaze me

regards, KiwiCraig

_________________
CRAIG LAWRENCE of AUSTRALIA
_____________________________________________

see my earlier post. there is no "correct" number. action height, string make/guage, etc., etc., all affect intonation. there are approximations, and there are specifics. you must make up your mind what you want!

   Hi
   I am with you now. When a scale length compensation is figured the other factors for the finaly length need to be figured into the equation.
    If you set you saddle to the proper scale length I am not worried about setting the scale lenth I am worried about the working length.
    On a 24.9 I set the saddle at 25.0 and on a 25.4 I set that up to 25.5. The extra length allows the string to work. I know this may sound wrong but your intonation will more than thank you for it. At this length my acoutics will intonate very well. Acoutisics unlike electrics seldom have perfect intonation across the line as you have to take the best you can get. With this you will be pleasantly surprised
john hall

When I set neck angle I pin the FB to the neck, hold the neck in position on the body, hold a straight edge on the FB and I want the straightedge to rest on the top surface of the bridge when the bridge is in it's final position (tape bridge to top). I used to set neck angle with a straight edge without the FB and then measure the gap at the saddle location. I have found more accuracy indicating off of the FB surface.

_________________
tim...
http://www.mcknightguitars.com

Your all a fantastic help guys. many thanks.
Tim, you say you set the neck angle with no air space above the bridge (with frets on I imagine?), and john you leave 1/16" to 5/64" air space
I suppose that's where my confusion starts.As this is my first , I have no idea of how my guitar will behave under tension i.e. how much my soundboard will pull up and neck etc.
this is why ,(on my first post) I described my "Aframe bracing and soundboard thickness etc. In the hope that you very experienced (and bloody clever ) guys could give me your opinion as to how much air space I should leave (given my type of build). It's just that I have the neck set and fingerboard extension seated about perfect now (about 1/16" airspace above bridge) and know this will be more difficult to change once fretted.
I imagine the F/board extension wants to curl down abit when fretted. I realise this would only be your opinion ,as each of your guitars would behave a little differently upon string tension, depending on what bracing system ,s/board thickness, etc. etc.

so.... should I leave at 1/16" airspace or what?......
I want too retain that 3/8"bridge and 1/8' saddle hieght on the finished instrument.

Many thanks and kind regards to you all   

       KiwiCraig

p.s. I have taken my 1/16" air space measurement by adding the hieght of (yet to be installed ) frets, to my bare fingerboard measurement.

_________________
CRAIG LAWRENCE of AUSTRALIA
_____________________________________________

I have no air space on bridge with frets installed or 1/16" with no frets. This gap is necessary to compensate for neck pull up under tension.Tim McKnight38599.8885300926

_________________
tim...
http://www.mcknightguitars.com

   You can't be flush as this will not give you enough angle to the saddle and your chances of buzzing are high.
    The geometry of the neck is this , a neck angle will establish the tie to the saddle. Depending upon building a classical or steel string the angle is often different between the 2. I am not a classical builder and will not elaberate on them .
   The action is going to be established by the neck angle and the bridge. If your neck angle is too flat the saddle will have to be increased and this will over stress the bridge area.
   If you are too high this is going to make you trim the bridge and establish some saddle height that way. I first establish my saddle postion and with the neck set into the joint without the fingerboard I want to see about 1/8 to 5/32 gap at the saddle location without the bridge. As I complete the instrument I will keep checking this so I can see my action is where I need it to be.
   We all build with different techniques and while some of the information may sound conflicting it may not be. I do thing that are Martinesque. Some people will build using cupiano and others may do things differently. Find what works for you.
    I use a 3 degree compensated saddle angle on the bridge , I set this to the scale length plus twice the thickness of my base string .
    The action I like to plan for is a 3 1/2 64 on the 1st and 6/64 on the 6th.
Good luck
john hall tippie5338599.9428935185

Tim, if I understand your post correctly you have no airspace where the bridge is with the frets installed and 1/16th with no frets installed? Shouldn't this be the other way around? When you install the frets the gap should get bigger, correct?
I assume you are working with a bridge of 3/8 inch?   

I have a 24' radiused top on my guitars. To set the neck angle I just have it so a straight edge on the Neck runs on the same angle as the top. Runs up and gives me a perfect gap at the bridge..

Well, I will be the first to admit that I am not the best at putting my thoughts into words. So look at the pictures on page two of Frank Ford's technique. Same way I set my neck angle. I hope this clarify's the issue at hand and my sincere apology if I have thoroughly confused anyone.

http://www.frets.com/FRETSPages/Luthier/Technique/Guitar/Nec kReset/00028Reset/00028reset02.html

_________________
tim...
http://www.mcknightguitars.com