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| Neck Stability & Lamination http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=9184 |
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| Author: | j.Brown [ Mon Nov 06, 2006 5:16 am ] |
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This is touched on in a similar topic, but I didn't want to take that somewhere the author didn't want to go. Does laminating a piece or pieces into the neck increase the stability a lot, a little, etc.? It seems like the following are factors in that answer: - The stability of the pieces you are laminating into the neck. - The orientation of the grain - The glue used to laminate with I build my neck first...scarf joint, stacked heel, and get it right. Then I cut the whole thing with a band saw and laminate solid pieces in, usually with the grain going 90 degrees to the neck grain. This eliminates the need to worry about the scarf or the stacked block pieces lining up. In my current neck, its essentially a 7 piece with Hard Maple, Watkins' Black Fiber, Cocobolo, Fiber, Cocobolo, Fiber, and Maple. All this is laminated with Polyurethane. Now it seems like a very stable neck. I shouldn't need to add carbon fiber to this, right? -j. |
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| Author: | TonyKarol [ Mon Nov 06, 2006 8:24 am ] |
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you could drive a truck over the new neck J .. it will be rock solid. |
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| Author: | j.Brown [ Mon Nov 06, 2006 9:10 am ] |
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Tony, that made me laugh out loud at my desk. I wasn't sure about the truck, but I was pretty sure it'd be stable. Thanks for the reinforcement. I guess I still have a lingering question about what exactly makes the neck more stable. i.e. if you just had a neck, cut it in half and glue it back together, is it inherently more stable because it is essentially a "laminated" neck? Is it the glueing or the material that offers more stability...or both? Thanks -j. |
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| Author: | KiwiCraig [ Mon Nov 06, 2006 9:26 am ] |
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Depending on the width of the centre lamination/s , I can't see a lot of strength being added to the neck when you subtract the depth of the truss rod slot . Seems to be more cosmetic Craig Lawrence |
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| Author: | Pwoolson [ Mon Nov 06, 2006 9:56 am ] |
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Do some strength tests. If you do it right it will increase the strength a LOT. The main reason I do it is to increase stability. I've got much more control over which direction the grain runs. I like to bookmatch the pieces so the grain is alternating. Makes for a very, very strong and stable neck. |
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| Author: | TonyKarol [ Mon Nov 06, 2006 10:15 am ] |
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strength comes more from choice of wood - not always weight independant, like rock maple. Stability comes more from grain direction, hopefully alternating/opposing such that one piece counteracts the others to move. |
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| Author: | Pwoolson [ Mon Nov 06, 2006 10:32 am ] |
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Good point Tony. However, a laminated neck usually has something like Maple adding strength to the mahogany. The glue joints, if done right, add a bit as well. |
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| Author: | KiwiCraig [ Mon Nov 06, 2006 10:38 am ] |
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With my greatest respect ,, how much material is left under the truss rod slot ? 1/8 " ???. I wouldn't think that enough to make any sort of strength difference . Craig Lawrence |
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| Author: | Pwoolson [ Mon Nov 06, 2006 10:49 am ] |
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But you are going to put a truss rod slot in a non laminated neck, aren't you. The steel in the rod will pretty much make up for the lack of wood. I know I'd certainly rather have 1/8" of maple behind my truss rod than 1/8" of mahogany. |
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| Author: | KiwiCraig [ Mon Nov 06, 2006 11:04 am ] |
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Millions of unlaminated Mahogany necks have been made without issues. .... Cosmetics me thinks. KIND regards to you Paul. Craig Lawrence |
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| Author: | KiwiCraig [ Mon Nov 06, 2006 11:21 am ] |
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I have nothing against laminated necks. I think they can LOOK cool . If the lamination strip/s were wider than the truss rod slot , I could see the added strength ,however most are not. Craig Lawrence |
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| Author: | Pwoolson [ Mon Nov 06, 2006 12:36 pm ] |
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You are entitled to your opinion. But I've seen many solid mahogany necks that have SERIOUS issues. If someone were to come to me and specifically not want the look of a laminated neck, I'd still laminate mahogany together to get the grain going in opposing directions. I guess we'll agree to disagree on this one. 
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| Author: | KiwiCraig [ Mon Nov 06, 2006 2:41 pm ] |
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Agreed 
Regards , Craig |
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| Author: | peterm [ Mon Nov 06, 2006 3:03 pm ] |
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[QUOTE=Pwoolson] Do some strength tests. If you do it right it will increase the strength a LOT. The main reason I do it is to increase stability. I've got much more control over which direction the grain runs. I like to bookmatch the pieces so the grain is alternating. Makes for a very, very strong and stable neck. [/QUOTE] I do it the same way. After I cut the neck in half, I flip the wood over and now the grain runs on the opposite direction. Do the same with the laminations! |
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| Author: | Kim [ Mon Nov 06, 2006 5:29 pm ] |
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I do not get the point being made here about only 1/8" of wood being behind the truss rod? To my mind the rod pushes upward, applying its load toward the underside of the fretboard when it is under compression and counteracting the strings tension, 1/8" or 18" no difference. As for laminations adding strength to structure, try this. Grab a 12" x 12" piece of 1/4" hardwood, BRW will do and get someone to hold it up for you while you play Bruce Lee and drive your fist of fury right through it, now try the same trick with some 1/4" ply. 
When we are discussing stability, and in doing are forced to consider that it is indeed the tension held with in a given board that is the driving force behind it's potential to be unstable. We should keep in mind that this tension does have a compounding affect. That is to say, that in general terms, the wider the board, the greater the potential for tension to not only be present, but to be present at a much greater force. One of the reasons that I would laminate wood is to relieve some of the tension held within a board. So you could look at it like this. Lets assume you have a 4" x 1" board, and you have also found a way to measure the tensions contained within this board. Your measurements clearly tell you that there is a constant 32lb psi of tension present, and from this information you now assume, that in time, this tension will eventually force the board to cup up toward what you have marked as the face and also produce a slight rotational twist in a clockwise direction sighting down the board from the end by which you now have it held in your imagination. So before time can play it's evil hand, you rip this board in half. Chances are that you have also just released at least half of the tension, and also divided what was left between the 2 narrower boards. If you now flip one of the 2 boards end for end, and glue them back together, in theory at least, the remaining tension in each board will cancel out the tension in the other. This will leave you with a slightly narrower, but much more stable board than you first started with, just ask someone who has built a few solid hardwood table tops
Cheers Kim |
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| Author: | j.Brown [ Tue Nov 07, 2006 6:00 am ] |
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Excellent analysis and insight, Kim. Thanks for all the thoughtful responses. -j. |
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