Maybe it would not hurt to leave a waterproof message on this in the gap
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| Dovetail Neck Joints http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=20288 |
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| Author: | Oubaas [ Fri Jan 02, 2009 1:21 pm ] |
| Post subject: | Dovetail Neck Joints |
Does anyone know if there is a book out there that covers the fundamentals and the fine points of creating and setting the dovetail neck joint? I've been self-teaching with Cumpiano's book, but as I'm sure everyone knows, Cumpiano does not use the traditional dovetail joint. And I'm a traditionalist. Usually. Before I move from pre-carved necks, I'd like to get hold of a tome that really goes through the subject of dovetail neck joints from start to finish, cutting and carving to installing and getting the angle right. Could you recommend a book? Thanks! Oubaas |
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| Author: | elysne [ Fri Jan 02, 2009 1:26 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
Benedetto covers a dovetail in his book on archtops. |
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| Author: | George L [ Fri Jan 02, 2009 2:32 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
I'm not a dovetail expert so I can't vouch for its accuracy, but I think Jonathon Kinkead's book addresses this as well. George :-) |
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| Author: | Parser [ Fri Jan 02, 2009 6:03 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
There's no teacher like experience...I would get a bunch of scrap wood and start making some sawdust! I have it from a good teacher that it is a good idea to "shim" the gap between the end of the dovetail and the neck block with something. This can help keep the joint solid over the years. |
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| Author: | bluescreek [ Fri Jan 02, 2009 6:29 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
It really is not a good idea to fill the void of the neck block. A dovetail joint is a mechanical joint. The action of the dovetail is to pinch together. To set a dovetail is not that difficult but you do need some hand skills. Here is a simple primer that I learned to set a dovetail necks that I pass on to my student . Using a chisel is an art. If you cannot shave with the chisel ,it is not sharp and can ruin your set of not the neck. Tools that you need are a good straight edge , a few sanding blocks that are angled to fit the dovetail angle and some chalk. Also you want a few strips if sandpaper 1 inch wide and a few inches long. I sue 80 grit You want to keep track if a few measurements as you go. You need to be aware of the center line of the neck in relation to the top. You want to keep the fretboard parallel to the top and last but not least , the neck angle. In most cases you want to have a final action where the height at the 12th fret is 3/64 on the 1st string and 5/64 on the 6th. I shoot for 1/2" of height at the bridge. Take the chalk and mark up the block. Place the neck into the block and take your measurement. I will use some masking tape to mark the tail area center and the area in front of the bridge. I measure how far up out of the block I am and with the straight edge , see how high I am at the bridge area. At this point I want to decide how I have to move things. I will make a few hash marks along the neck's heel so I use them as a reference. If I need to bring the neck up I can take my sanding block and work the first section of the heel then I move up to the 1st and 2nd mark then 1st , 2nd , and 3rd etc. If you need to adjust the center line you can take a strip and set that between the side and the heel with the abrasive against the heel. The nice thing about this method , if you are not familiar with chisels you can take material off in a very controlled manner. I like to see about 1/8 more height at the bridge than at the joint. You should have a 3/8" thick bridge. Once you have the neck angle and center line established you can start working the dovetail tenon. Once you pull the neck you will see chalk on the tenon , and you know where you are high. Work slow and you can get a very clean and secure joint. As you start to work the dovetail you want to check the security of the joint. If the top is loose , you need to work a little off the bottom. You also want to be sure not to splay the joint. As the chalk footprint changes you want the lower 2/3 of the dovetail to be biting. You also need to round off all mating corners. If you have a corner holding off the joint , it can't mate. Again , please allow the gap at the end of the joint tenon. Shimming this will cause you some issues when you try to steam out the joint later. Use tite bond or HHG . I use tite Bond but I know of you out there prefer the HHG. Hope this info helps. |
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| Author: | TonyKarol [ Fri Jan 02, 2009 6:30 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
Agree on one item .. its good to practice to get a dovetail to fit properly, with the right back angle and centred ..... But I would strongly advise AGAINST putting ANYTHING in the dovetail gap - between the end of the dovetail and the neck block. There is a huge reason for the gap - thats where the steam goes and softens the glue all round the dovetail when you need to reset the neck - no gap ...haha .. have fun getting that sucker off ... A properly fitting dovetail need only a smidge of glue in there, plus the FB ext glued down to hold it for years. As well, I would make the gap directly under the 15th fret .. easy to find when the repair day comes around. One of my students bought a decent, but in need of a reset guitar that some idiot reset with what looked like epoxy - the smallish gap was filled solid, and there was nowhere for the steam to go and soften anything. After heating/cutting the FB ext off to see all this mess, we had to knock it out with a hammer after drilling a bunch of holes into where the gap would have been, and down the sides fo the dovetail. Then we had to rebuild it. |
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| Author: | Alexandru Marian [ Fri Jan 02, 2009 6:51 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
Maybe it would not hurt to leave a waterproof message on this in the gap
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| Author: | Ricardo [ Fri Jan 02, 2009 7:07 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
I've shimmed a dovetail only on the cheeks. I like the joint, but the difficulty in fitting is you can't sand a fit like you can with a straight bolt-on because you have to raise the tenon up a bit to get sandpaper between the body and the neck. A good fit is a bit trickier. |
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| Author: | Oubaas [ Fri Jan 02, 2009 7:16 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
Wow! Thanks for all the information everyone! Practicing is definitely on the agenda. We just finished some major renovating on the house and I've got lots and lots of practice wood around now. So if anyone is looking for some really ugly, poorly done dovetail guitar necks in old loblolly pine, I should have a pile of them available awhile from now, LOL! Rick 
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| Author: | Parser [ Fri Jan 02, 2009 7:59 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
The explanation I got was based on the idea that the neck should not ever need to be reset. It was also based on the idea that if the fit of the neck/glue joint had somehow degraded over the years, the first place it would "slip" would be at the top of the dovetail. Maybe a good (or bad?) compromise would be to shim at the sides of the back of the dovetail, but to leave a gap in the center for steam...just in case? I also appreciate hearing another side of the issue! Best, Trev |
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| Author: | bluescreek [ Fri Jan 02, 2009 8:29 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
Ricardo Once you master a Dovetail , you can appreciate the the joint. You can get a joint , that when done well , will be able to be strung up dry. They are a traditional joint and if you are going to try to make a living at this , you need to master them. I pre fit the neck without the fret board . Using a signature material like chalk or carbon paper lets you know the high spots without guessing. I have seen poorly fitted M&T joints also. Take your time and you can do it. john hall |
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| Author: | bluescreek [ Fri Jan 02, 2009 8:33 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
parser ignore what that guy told you. I think he doesn't know what he is doing when it comes to dovetails , or he was pulling your leg. A dovetail may need a reset. If the joint isn't done right that shim isn't going to help. |
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| Author: | Ricardo [ Fri Jan 02, 2009 8:33 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
John, I agree I want to be a master at dovetails. I used colored line chalk to mark the high spots. With the style of guitar that I just built with upper bout sound holes I needed to use dove tail joint. I also fit the neck without the fretboard then put the finished fretboard on and it worked great. I was careful to make sure that I had the correct angle to the top so slapping on the fretboard created no problems. I'll do it again on my next axe. Thanks.
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| Author: | bluescreek [ Fri Jan 02, 2009 8:40 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
A little tip, when you set the neck , allow the neck to be about about the thickness of a business card so you have a good interference fit. It is amazing how tight this joint can get john |
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| Author: | Parser [ Fri Jan 02, 2009 9:41 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
I'm sure if there's one thing you Martin guys have figured out, it's dovetails. Thanks for the info! Trev |
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| Author: | Darryl Young [ Sat Jan 03, 2009 12:13 am ] |
| Post subject: | Re: Dovetail Neck Joints |
Quote: A little tip, when you set the neck , allow the neck to be about about the thickness of a business card so you have a good interference fit. It is amazing how tight this joint can get john John, can you elaborate? What do you mean when you say ".....allow the neck to be about the thickness of a business card so you have a good interference fit." I understand what an interference fit is. Do you mean leave the neck proud of the final level by half the thickness of a business card or something else? |
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| Author: | bluescreek [ Sat Jan 03, 2009 7:24 am ] |
| Post subject: | Re: Dovetail Neck Joints |
that is what I mean. I like the final few thousandths to be forced into the block. This assures a good solid fit. As long as I can slide a business card under the fret board at the neck joint , that is what I like to see. With a little time you will master this joint. I agree that a bolt on and dovetail neck , really doesn't affect the sound of the guitar , this joint is still a fantastic piece of artwork. I am a traditionalist style builder and just enjoy the simplicity . If you do ever need to shim a joint ,be sure to shim on the tenon area of the block. I took me a year or so of working this joint to really master it , but it paid off. I use mahogany for shims when I need them. If you need some you can take a board and use plane curls , they iron out nicely. john |
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| Author: | justink [ Tue Jan 27, 2009 11:11 pm ] |
| Post subject: | Re: Dovetail Neck Joints |
I am about to attempt my first dovetail neck joint so I REALLY appreciate all this input too. Thanks everyone. One question, I have a friend who is a great guitar player and has built about 6 of them. He claims that he can actually hear a "metallic" sound when he plays a bolt on neck versus a dovetailed neck. Can/does anyone else hear this? I know my hearing is not even close to good enough to ever hear this, but I was just curious. Thanks again all. |
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| Author: | David Collins [ Wed Jan 28, 2009 12:22 am ] |
| Post subject: | Re: Dovetail Neck Joints |
Getting good with dovetails just takes practice. I haven't read many of the recent guitar building books (anything published in the last 15 years), but of the older books at least, many teach more methods and procedures without imparting a true understanding of why they must be that way. It really all just comes down to developing an intimate sense of the geometry involved, which is really nothing more than reasoning and thinking about each facet. You just have to think like a dovetail. There are three angles to consider - pitch (angle of fingerboard plane above top plane), roll (angle of fingerboard from side to side), and yaw (angle of centerline of board relative to centerline of top) if you will. http://en.wikipedia.org/wiki/Flight_dynamics Then there are three axis - x (movement of fingerboard toward or away from bridge), y (movement of fingerboard side to side, perpendicular to the centerline), and z (movement of fingerboard down toward or up away from the face of the guitar). The shoulder/heel joint primarily influences pitch, yaw, and x. The fit of the dovetail primarily influences roll, y, and z. Then of course the tightness of fit determines the tightness and stability of the joint. Too tight and you won't be able to clamp it all the way down (or on rare occasions may split the block or crack finish). Too loose and the heel can pull away. You should typically have to clamp the neck to get it down the last .030"-.070", depending on the angles of the dovetail. Being conscious of these 6 angles and axis simultaneously is what it takes to be fluent in dovetails. If you are aware of these and follow simple geometrical reasoning, every change than needs to be made will point to what surface(s) must be modified. Likewise, every time you alter a surface you must be aware of each plane it will effect, and adjust your cutting or sanding with that in mind. If every bit of material removed is intentional and well thought out, you can fit a dovetail. If you can keep all this in mind, the learning curve is largely a matter of developing your hand and tool skills, and of speed at which you mentally process the geometry. There need not be any mystery about it at all though. The more you do it, the faster the geometry will become auto-programmed in your brain. After a while you don't have to struggle to keep all the variables orderly in thought - you just know where to cut. Likewise your hand tool skills particular to this joint should develop in parallel. I can set a dovetail neck in about the same time it takes me to set an M&T bolt-on. It really just takes reasoning and practice, and it doesn't take long before you wonder why it ever sounded so intimidating. And as pointed out by others, shimming or wedging to fill the gap at the end of the serves no real redeemable purpose, and in the end would only interfere with serviceability. As to the friend who claims to hear the difference, they can't. It's a common traditionalist stance, but it's a psychosomatic, psychoacoustic issue of their perception being effected by their predispositions. |
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| Author: | JusSumguy [ Wed Jan 28, 2009 1:29 am ] |
| Post subject: | Re: Dovetail Neck Joints |
http://gicl.cs.drexel.edu/people/sevy/l ... joint.html 
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| Author: | justink [ Wed Jan 28, 2009 10:32 am ] |
| Post subject: | Re: Dovetail Neck Joints |
Another question, Does it matter if you install the binding and purfling around the body of the guitar before or after you cut the dovetail to fit on the neck? I already have the mortise cut on the body, but haven't bound the body yet.... Should I do this before preceeding with cutting the dovetailed tenon? |
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| Author: | jordan aceto [ Wed Jan 28, 2009 10:42 am ] |
| Post subject: | Re: Dovetail Neck Joints |
I install binding before routing for the dovetail, because if you cut a big slot there the bearing can fall into it when you go to route for bindings. If you do need to do some handwork to the binding channel there, it is not so hard though. Another reason to do the bindings first is that you want to be done sanding and messing with the shape of the sides before you fit your dovetail. |
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