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Distance Off The Top At The Saddle
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=50747		 Page 2 of 2
Author:  Freeman [ Wed Jun 20, 2018 5:45 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
Julie, you've been give several different answers to your question ranging from 2.3mm to 2.5, 3.0 and 3.5. You might want to draw up a side view of your guitar with all the parameters that you are actually using and see which one works the best. Autocadd is your friend.

Jules wrote:
There was an article in AL where a guy created a jig that would slide over the end of the guitar to accept strings. He could then slide a saddled bridge under it to find the correct bridge location. That might help me understand the relationship to all the factors in place. I learn much better watching and experimenting than reading.


That gizmo was sort of a tailpiece that didn't require any hardware to mount it. Your guitar will have a pinned bridge. You could use that tailpiece thingie to locate and check your intonation but it will tell you nothing about neck angle or any of the other things you have been agonizing over. Guitars with tail pieces and guitars with pinned bridges work differently (Brad mentioned on of the differences above)
Author:  Jules [ Thu Jun 21, 2018 10:18 am ]
Post subject:  Re: Distance Off The Top At The Saddle
Freeman wrote:
Julie, you've been give several different answers to your question ranging from 2.3mm to 2.5, 3.0 and 3.5. You might want to draw up a side view of your guitar with all the parameters that you are actually using and see which one works the best. Autocadd is your friend.

I'm going to have to build or buy a neck set jig. Sipo is such a hard wood, flossing is getting me nowhere, except rounding the edges. I need to square that up. I've tried using a shoulder plane but it just skipped across the end grain. So I'm going to a router jig.

I've been working on an AutoCAD drawing. The difficulty comes in duplicating what I've already built. Though I created a radius for all the braces, that same radius does not transmit across the section perpendicular to the bridge. It's almost flat. I had to use feeler gauges to take measurements.

Freeman wrote:
You could use that tailpiece thingie to locate and check your intonation

That was my primary intention but it could also serve as a visual to see how everything goes together.
Author:  Clay S. [ Thu Jun 21, 2018 10:33 am ]
Post subject:  Re: Distance Off The Top At The Saddle
Hi Julie,
What many of us do is undercut (relieve) the inner surface of the heel so you only have the outer edge to floss. as you floss more of the heel comes in contact with the body, but most of the unseen part of the heel isn't.
If you know about how much you need to take off you can remove the majority with a file (I like to use a laminate file) and only floss the last little bit - less chance of rounding things over.
Author:  Freeman [ Thu Jun 21, 2018 11:21 am ]
Post subject:  Re: Distance Off The Top At The Saddle
You are making this so much harder than it needs to be. Feel free to build all the jigs and gizmos you feel you need, I sure haven't found that I do.

Undercut the heel next to the tenon with a chisel leaving only about 1/4 inch contacting the body on the outsides. It barely shows here

Image

Also there needs to be a small gap at the end of the tenon so only the cheeks contact the body. It doesn't matter what kind of joint you are using - dovetail, M&T, bolted - this happens to have two threaded inserts in the heel and bolts from the inside. When you floss the cheeks make sure you keep the center line of the neck lined up with the center line of the body.

You must of done it when you built your electric guitars, it is the same for an acoustic.
Author:  Freeman [ Thu Jun 21, 2018 11:41 am ]
Post subject:  Re: Distance Off The Top At The Saddle
I just took a quick look at my old Cumpiano and in figure 13-32 he shows a straightedge on the fretted fretbord and is measuring to the top at the bridge location. He say "airspace at the saddle location must be 1/64 to 1/16 greater than the height of the bridge". He also shows "shaving the bearing surface of the heel to adjust the backset of the neck" One more number for your collection.....
Author:  Jules [ Fri Jun 22, 2018 8:37 am ]
Post subject:  Re: Distance Off The Top At The Saddle
Thanks, Freeman. I hadn't thought about undercutting. And yes, I know I'm making this harder than it needs to be. Part of that comes from my newfound aversion to sipo. Besides being rock hard, I am terribly allergic to it. I found that out the hard way. I've come to hate this wood and get easily frustrated with how difficult it is to work with. I find myself dreaming of the days when I could buy genuine mahogany with a quick trip to the hardwood warehouse nearby.

I'll give the undercutting a shot. But first I have to hermetically seal myself. :roll:
Author:  Jules [ Wed Jul 04, 2018 12:45 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
Is this acceptable or does the straight edge have to be perfectly flush with the top of the bridge?
Image
Author:  Joe Beaver [ Wed Jul 04, 2018 1:12 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
I shoot for around a 1/32" clearance over the bridge. (Others may have different preferences). Your photo looks very close. If you are wanting to add a little more clearance it won't take much flossing.

And your build looks great!
Author:  Joe Beaver [ Wed Jul 04, 2018 1:24 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
But.... I am taking about a fretted board. If yours is not fretted it just might be perfect
Author:  DennisK [ Wed Jul 04, 2018 4:40 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
Jules wrote:
Is this acceptable or does the straight edge have to be perfectly flush with the top of the bridge?

How thick is that bridge? It looks pretty low to me. Get a short ruler and measure the distance from the soundboard surface to the straightedge.

Are the frets in yet? That will get you about 1mm higher.
Author:  Freeman [ Wed Jul 04, 2018 6:07 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
I shoot for the fretted f/b plane hitting the top of the bridge. Stack four business cards (0.010 thick) on each end of the board and try again.

FWIW my bridges are 3/8 thick and I like the saddle about 1/8 out of the slot (which puts the strings about 1/2 over the top). I've heard that it is desirable to have 2/3 of the saddle height in the slot so I make my slots 1/4 or a little more deep.
Author:  Jules [ Wed Jul 04, 2018 9:17 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
That pic is off a fretless FB. The bridge is 0.3625" at the center, sanded to the radius of the top. Frets I have are .048, before leveling of course.
Author:  DennisK [ Wed Jul 04, 2018 11:16 pm ]
Post subject:  Re: Distance Off The Top At The Saddle
Jules wrote:
That pic is off a fretless FB. The bridge is 0.3625" at the center, sanded to the radius of the top. Frets I have are .048, before leveling of course.

Should be good then.
Author:  jfmckenna [ Thu Jul 05, 2018 9:19 am ]
Post subject:  Re: Distance Off The Top At The Saddle
Freeman wrote:

Then I'll fret the board, glue it on the neck, check the angle again and floss if I need to, shoot some paint at it and check the angle again.... Put it together but I don't glue the f/b down, glue the bridge on (I do it after the neck is finally positioned to minimize the intonation shift. Make a nut and saddle and pins and things, put strings on and check that angle again. Eventually I'll take it apart, maybe make a minor floss but its usually not necessary and lightly glue the f/b extension down. My oldest guitar is 12 now, its neck angle is perfect as are all the others that followed.

There was a big techie article in AL a while back about calculating neck angle on an acoustic guitar. I'm an engineer, I took one look at it and said "the only reason someone would write an article like that was to put it in a magazine, there was nothing there that would help me set a neck"




This is the way 'I do it' too :D What I have found is this gets me to a saddle of about 5/32 which is what I aim for. With 1/8th generally considered to be the optimal height I like to go a hair taller so that the guitar can at least have one or two setups before needing a neck reset. And as mentioned sometimes they move more then you think in the coming year.

And yes there is always a time and a place for numbers for things but not when you can do empirically so much easier and more accurately.
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