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| Setting Neck Angle - Exact Science? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=4018 |
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| Author: | CarpeNoctem [ Wed Dec 07, 2005 2:07 am ] |
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A lot of books that 'teach' guitar making talk little about neck angle settings. Rather they don't explain the cause and effects of different neck angles. Sure, it's safe to assume a high neck angle (from 90) will lower the action, while a lower / negative neck angle will increase the action. Since you must set the neck angle before stringing up, and your decisions on what strings to use are generally made before you start the project, is there a method you use to set the initial neck angle (not under tension)? Also, is there a 'safe' road to travel here? Meaning, how do you progress in this area, but keeping an 'ace in the hole' if something doesn't go as planned? Could you string up the guitar to tension without gluing the neck to the body? That way if you'd like to make some angle adjustments you don't have to 'unglue'. Thanks, Rick |
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| Author: | tl507362 [ Wed Dec 07, 2005 2:14 am ] |
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Rick, I know of no sure fire way of getting the neck angle correct before getting the body and neck made. But I always string mine up before gluing the bridge down to test for neck angle and compensation. I use a mortise and tenon bolt on neck. The bolts are plenty strong enough to hold the neck on while you play it. I use 2 hollow bolts on the bridge to keep it down. You can get these from stew-mac. Also, you might want to check out John Mayes DVD on neck setting and double mortise and tenon neck. With this DVD you should be able to set your neck no problem! You can get it here! Tracy |
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| Author: | Wayne Clark [ Wed Dec 07, 2005 2:26 am ] |
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Rick, I would recommend John Mayes most recent dvd. The first half is devoted to just this topic, and his approach is pretty straight forward. In my limited experience, I roughly set the neck angle when I cut the tenon. I use a straight edge to find the bridge height and fine tune the angle by sanding material from the heel. I also make sure the neck is aligned with the center of the guitar at this point. It takes me a while, sanding a little then measuring. When I am satisfied I bolt the neck on. I fine tune the action when I make the nut and saddle. Things change a bit after its strung up, but the changes seem to be pretty small and can handled by making small adjustments at the nut and saddle. |
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| Author: | CarpeNoctem [ Wed Dec 07, 2005 2:28 am ] |
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Thanks for the link! Gonna have to tell the LOML I'd like the DVD set for Christmas. You mentioned you string up before you glue, but also you use a Bolt M & T joint. Considering a string tension of between 60-80 newtons per string (average guitar tensions) do you think that a dovetail joint would survive? Of course I don't think it would be destroyed, but it may be 'distorted'. I know that when I test fit through and half blind dove tail joints on corner assemblies, I have to be careful how many times I test fit the joint, because each time I test fit, the joint is 'expanded' ever so slightly. And it's worse if I flex the joint. (put tensions on the joint) (Of course, this is worse with soft woods, but remains noticable with hard woods) Thanks again! Rick |
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| Author: | CarpeNoctem [ Wed Dec 07, 2005 2:36 am ] |
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Wayne, Thanks for the info. You and Tracy seem to be in exact agreement about the DVDs and how you test your neck angles. I'm not worried about small changes and rechecking. I'm pretty fussy about that sort of thing. (Guess it's a side affect of being a software designer and developer) Both you and Tracy seem to be preaching from the same bible here. And I think that's the answer, a method to accomplish the neck angle without committing yourself to something that may not work. Thanks again everyone! Best regards, Rick |
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| Author: | RussellR [ Wed Dec 07, 2005 7:44 am ] |
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Hesh I aim for about 1/8" of Saddle above the top of the bridge, maybe a smidge less on the little E. If you are looking for a sure fire way to control neck angle, Paul Woolson has a jig for this, which I now use, I believe Paul is working on some plans. |
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| Author: | Michael Dale Payne [ Wed Dec 07, 2005 7:56 am ] |
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Good news...Paul Woolson and I have been working on OLF plans for his Neck Tenon Fixture. This fixture presets the back angle of the neck based on the height and location of the bridge for an individual guitar. It is a really cool fixture. It is not perfect but according to Paul it leave very very little of minute adjustment to do. I will be sending Lance the originals for this set of plans as soon as I get back to Odessa, So they should be available very soon  |
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| Author: | CarpeNoctem [ Wed Dec 07, 2005 8:22 am ] |
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Hesh, Thanks for the tip on checking the neck angle. About the optimum saddle height, I am working on it mathmatically. (I got stuck here at work on something and decided to work on this problem) I will post my results here once I figure it out. If you want to work on it, look into the rule of sine and rule of cosine. Hopefully I can crack this nut, it's definitely a challenge. LOL -Rick |
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| Author: | RussellR [ Wed Dec 07, 2005 8:44 am ] |
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Hesh I mean when I am done I am looking for this amount of sadle above the bridge and at least 4mm inside. The way I do it is I use the jig to set my clearance an the bridge position, which has been calculated to allow for fret height, difference in thickness between bridge and fingerboard, and my back set etc., in my case this is 2.8mm. I then know this will give me enough saddle showing and the correct neck set angle. before I used this jig I used to used shims and a straight end to replicate the string path so I could check the height whilst setting the neck. I would then fit the neck first fret it and check the amount of saddle using shims to replicate the action at the 12the fret, then if need be thin the bridge. Hope this helps. |
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| Author: | John How [ Wed Dec 07, 2005 8:44 am ] |
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Hesh, try using your straight edge right on the fingerboard with no frets and shoot for the top of the bridge or just a little higher depending on the height of your bridge. That should give you about an 8th inch of saddle after your fretted and strung up. I like to err with a little more saddle if anything that way as the belly swells (which it will if you made the top light emough) you can reduce the saddle height to keep your action right. |
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| Author: | Wayne Clark [ Wed Dec 07, 2005 9:08 am ] |
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I don't have notes on the exact bridge thickness here, but I think its on the order of 8-10mm. I do something similar to Russell - I shoot for having 3.5 to 4mm of saddle material sticking up above the bridge. When I set the neck angle the frets are already on the FB. I lay a straight edge on the neck and measure the distance above the soundboard at the saddle position. I shoot for a gap of about 10mm at the bridge. Paul Woolson's jig that Michael mentioned is a real nice solution. There is a picture of it somewhere in the archives. I have been sketching a plan to build one. It sounds like plans will be available shortly. |
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| Author: | Michael Dale Payne [ Wed Dec 07, 2005 9:53 am ] |
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yep they are drawn just need plotted and mailed to Lance |
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| Author: | Brock Poling [ Wed Dec 07, 2005 11:13 am ] |
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I can definitely vouch for the neck tenon jig. It really works great. |
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| Author: | CarpeNoctem [ Wed Dec 07, 2005 12:16 pm ] |
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Well I wish that I can give you some sort of magic number, back by charts and graphs. But I can't. All I can do is say, since the 12th fret is 1/2 the scale length, take your target action height of each string at the 12th fret and double it. That will give you the height of the saddle above the flat plane created by the surface of the frets, and extended through infinity (or to the bridge, depending on your visualization). Now the train of thought, maybe someone else can fill in the blanks. But that by itself is meaningless unless you know where that plane resides in relationship to the soundboard. We know that at the 14th fret (fret at body/neck joint) the action here is 0.0693" if action is .0625" at the 12th fret. This point is signifigant because the neck angle stops here, in basic theory. But the plane continues on through. It might be reasonable to assume that the plane ends right under the saddle on the soundboard. But this implies that the top of the saddle is 1/8" above the soundboard, and that is unreasonable. The plane must intersect at some point under the soundboard. Sorry I could get any more than that, but I just could figure it out. Maybe someone else can help out here. -Rick |
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| Author: | Bobc [ Wed Dec 07, 2005 1:16 pm ] |
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[QUOTE=Hesh1956] Wayne what you do sounds like what I do. I am looking to make this a bit more of an exact science though. Here is my question for you and every one else. I use bolt on necks and when I set the angle I remove material until a straight edge placed across the frets (I have been freting prior to installing the neck) just skims the top of the bridge with the bridge placed where it is going to live. I am finding that my saddles turn out being to short for my liking once I adjust the action to a low action set up. Is there an optimal height for a saddle to be on a new guitar with low to medium action? I am looking for a taget to shoot for here. Also, I just bought a jaws II from Stew-Mac and plan to fret my necks now after the fret board is on the neck and the neck is on the guitar but the guitar not yet finished. With this in mind I will be checking the angle with a fretted neck installed. Like you Wayne I also check the alignment of the neck at this stage to and adjust accordingly. I do this by making a mark on the true center of the top at the bottom purfing. Another mark is made just over the sound hole in the center of the fret board extention. The last mark is on the fret board just below the nut. If all three marks line up I am good to go (or so I think..). Thanks, Hesh[/QUOTE] Hesh if your straight edge is on the frets then you need to add that thickenss above the bridge. Like John How said: Without frets just skim the top of the bridge or a hair above. On a fretted fb you should be about 1/16" above the bridge. |
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| Author: | JJ Donohue [ Wed Dec 07, 2005 3:31 pm ] |
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I'm chomping at the bit to build that jig. Looking forward to having the plans available for sale. Thanks Paul, Lance & Michael! |
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| Author: | Pwoolson [ Wed Dec 07, 2005 3:54 pm ] |
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Just as a little teaser...Craig Holden will be having it availabe as well in the near future. So if you are at a loss for time to make it, give him a jingle. |
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| Author: | L. Presnall [ Thu Dec 08, 2005 2:30 am ] |
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Even better! 
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| Author: | Don A [ Thu Dec 08, 2005 7:00 am ] |
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[QUOTE=Pwoolson] Just as a little teaser...Craig Holden will be having it availabe as well in the near future. So if you are at a loss for time to make it, give him a jingle. [/QUOTE] I got an email from Craig just this week saying that the neck jig is in the works. I just wasn't sure if I should post it here.  
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| Author: | L. Presnall [ Fri Dec 09, 2005 3:52 am ] |
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| YES!
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