akozols Posted January 22, 2006 Report Share Posted January 22, 2006 HI, I love to work on my guitars. I'm self-taught and have learned everthing from trial and error. I'd like to pass on my latest error. I have a guitar that's all mahogany with a set in neck. The neck was also mahog with a poly finish. I decided to sand the neck down to a slimmer contour. What did I learn?? If you shave a mahogany neck down too slim, it turns into a rubber band. Just holding an open E chord whould make the neck wobble out of tune. I cut out the section of the body, and will try to glue in a solid block of mahogany, then route out a spot for a bolt-on. Does this sound like the right option? thanks, al Quote Link to comment Share on other sites More sharing options...
thegarehanman Posted January 22, 2006 Report Share Posted January 22, 2006 (edited) You aren't interested in making a set neck from scratch? It can be done. The wobbliness of the neck could be due to flatsawn lumber. I have a really thin quartersawn mahogany neck on my first build and it's plenty sturdy. Gluing in the block and rerouting for either a bolt on or set neck is a good route. Just make sure all of your joints are tight. peace, russ Edited January 22, 2006 by thegarehanman Quote Link to comment Share on other sites More sharing options...
ninoman123 Posted January 22, 2006 Report Share Posted January 22, 2006 Im going to make my own mahogany neck soon. How thin is too thin? Perhaps you could have reinforced it with some of those carbon fiber rods that they sell at Stew Mac. Ive got some flatsawn mahogany that I plan to use for my neck. I plan on using a nice sturdy truss rod and two carbon fiber rods on either side to reinforce it. I dunno, maybe Ill end up trying to get some quarter sawn...Ill just see how this works out first. Quote Link to comment Share on other sites More sharing options...
akozols Posted January 22, 2006 Author Report Share Posted January 22, 2006 Right now I just want to get it back together. I have a neck that I really like and can use that for now. al Quote Link to comment Share on other sites More sharing options...
Mattia Posted January 22, 2006 Report Share Posted January 22, 2006 Wood is wood; immensely variable. The floppiest necks I've ever had the 'pleasure' of playing have been flatsawn maple bolt-ons, for the record, and my regular sized warmoth all-mahogany (non-CF reinforced) neck is as stable as anything I've built. Re: stiffness, quartered vs. flatsawn doesn't make much of a difference for most tropicals, including mahogany, when it comes to stiffness. Stability yes, stiffness less so. I've never had problems with mahogany necks, although of late I do always use CF rods to even out the stiffness. Gluing a block in and routing for a bolt on should work fine. Quote Link to comment Share on other sites More sharing options...
SwedishLuthier Posted January 22, 2006 Report Share Posted January 22, 2006 Some info on quartersawn vs flatsawn neck blanks: I’ve read about a scientific experiment that shows that the strength is actually greater with a flatsawn neck compared to a quartersawn neck!!! The quartersawn test piece flexed over 10% more (static load). Check out Roger Siminoffs book “the luthier’s handbook” for more interesting information about what’s considered “facts” in the guitar building world. For an ultra thin neck I would suggest a laminated neck with carbon fibre reinforcements. I’ve done tests myself to investigate the best possible ways to use reinforcements. Check out the results here: http://projectguitar.ibforums.com/index.ph...ndpost&p=216422 Quote Link to comment Share on other sites More sharing options...
Mattia Posted January 22, 2006 Report Share Posted January 22, 2006 I take everything Siminoff has to say with a nice, big grain of salt. He's got some 'interesting' ideas on the science involved in instruments. The numbers for various species are out there, published, done via proper research (unless Siminoff presented data for a statistically significant number of neck blanks, all sized and selected for maximum similarity, and checked the data statistically, I'm inclined to go 'hmm, ok then). Unless you do all that, it's anecdotal evidence, and a good basis to design an experiment around, but it's not an experiment in and of itself that's particularly meaningful. Either way, it also very much depends on the species as to which of the two orientations is the stronger, but quartered wood is more stable. Quote Link to comment Share on other sites More sharing options...
SwedishLuthier Posted January 22, 2006 Report Share Posted January 22, 2006 Mattia, I'm not going to debate Mr Siminoff"s virtues. Being an engineer by training I enjoy his scientific approach compared to a lot of builder's tendency to walk a safe and known path. In this case I was referring to an experiment that I find very interesting, and that actually proved that Mr Siminoff's test piece of maple were stronger (less deflective under static load) when used as quartersawn compared to flatsawn. His experiment follows all your criteria, unless for one thing: the test pieces were cut from the same plank. The test showed that the flatsawn piece (1/2"x1/2"x4.25") flexed .052" under the load of eight pounds. The quartersawn piece flexed .05". A difference of more than 10%. This makes me doubt the old "truth" that the neck should be made out of quartersawn wood. But nevertheless I'm very interested in the data you are referring to, that prove quartersawn wood to be more stable than flatsawn. Are those data available online? Any good link? And when you say "more stable" what exactly do you mean? I guess more resistant to flex caused by static load. At least that is what I refer to. EDIT: The quartesawn piece lexed .058". Slight type-o Quote Link to comment Share on other sites More sharing options...
bugman96 Posted January 22, 2006 Report Share Posted January 22, 2006 The test showed that the flatsawn piece (1/2”x1/2”x4.25”) flexed .052” under the load of eight pounds. The quartersawn piece flexed .05”. A difference of more than 10%. This makes me doubt the old “truth” that the neck should be made out of quartersawn wood. The way you described it, that doesn't tell you anything-- you described one instance. Was the experiment repeated? Repetition and some statitiscal analysis would help to determine if that result occurred by chance or it is representative of quartersawn and flatsawn wood of the species he tested. It could be a fluke for all we know. It's also possible that flatsawn could be stronger than quartersawn at certain thicknesses. Quote Link to comment Share on other sites More sharing options...
SwedishLuthier Posted January 22, 2006 Report Share Posted January 22, 2006 Ok. This thread isn’t about that experiment, but OK. I missed one number. The quartersawn piece flexed 058”. The test was repeated three times. The same result every time. And the test pieces were square. Actually he used the same pieces flipped over. So the same pieces were stronger flatsawn, compared to quartersawn. If flatsawn is stronger in one thickness I cannot se how it would be weaker in another thickness. If you want to know everything about the experiment I recommend that you get the book. Siminoff have some interesting (interesting, not necessary the almighty truth) ideas about stringed instruments. You don’t have to believe everything he writes but he gets me thinking that we too often just do as we are used to. Quote Link to comment Share on other sites More sharing options...
Mattia Posted January 22, 2006 Report Share Posted January 22, 2006 (edited) But nevertheless I'm very interested in the data you are referring to, that prove quartersawn wood to be more stable than flatsawn. Are those data available online? Any good link? And when you say "more stable" what exactly do you mean? I guess more resistant to flex caused by static load. At least that is what I refer to. EDIT: The quartesawn piece lexed .058". Slight type-o See, that it flexed more doesn't really tell me if that's within the standard deviation for flex or not. I'm fairly certain Hoadley's 'Understanding Wood' has figures on strength, stiffness, etc. for various cuts of wood. 'Stability', in my book, has nothing to do with flex-resistant. That would be stiffness, possibly strength, maybe elasticity. Elasticity would also be important (as in, does it return to original shape, or hold the old one? This is one area where CF is a massive improvement over wood; zero memory effect. Bend it like crazy, it'll pop right back where it was. Every time. That's one of the reasons I use it). When I say stability I mean purely dimensional stability, not load resistance (although under load, with a straight-grained quartered piece of wood, the load is evenly distributed over the various layers; flatsawn wood is rarely so uniform). Resistance to warp and deformation. A quartersawn blank shouldn't cup along the fact the fingerboard is glued to if exposed to crazy temperature/humidity swings, but flatsawn wood can and does move less predictably. Skew sawn is the worst of all, but quartered wood is the most dimensionally stable in this context. The thinner the piece, the more this matters (case in point, guitar backs/sides). Quartered wood can be a bit more split-prone (along grain) than flatsawn, but that's a risk I can deal with. I only have epirical evidence and a body of anecdotal information to back my play on that one. I believe Al Carruth posted a few numbers re: strength differentials between flatsawn and quartered spruce guitar tops; the difference was relatively minimal, but quartered is still better for stability's sake. Edited January 22, 2006 by mattia Quote Link to comment Share on other sites More sharing options...
SwedishLuthier Posted January 22, 2006 Report Share Posted January 22, 2006 Ah, OK. You mean that a neck should be made out of quartersawn wood mainly because of its dimensional stability. I couldn’t agree more with you on that. But I am under the impression that most people choose quartersawn because they think that it is structural stronger (were resistance to flex is one of the factors) and not because of its stability. In this case I have only seen Mr Siminoff’s test that is actually a test based on facts. On the opposite side I have only got opinions based on, well… opinions, and because I’m an engineer I like scientific facts. I’ll try to get my hands on Hoadley's book and do a search for Al Carrut for more input. It will be very interesting reading I totally agree with you on the use of CF. I use it all the time for the same reason Quote Link to comment Share on other sites More sharing options...
Mattia Posted January 22, 2006 Report Share Posted January 22, 2006 Ah, OK. You mean that a neck should be made out of quartersawn wood mainly because of its dimensional stability. I couldn’t agree more with you on that. But I am under the impression that most people choose quartersawn because they think that it is structural stronger (were resistance to flex is one of the factors) and not because of its stability. In this case I have only seen Mr Siminoff’s test that is actually a test based on facts. On the opposite side I have only got opinions based on, well… opinions, and because I’m an engineer I like scientific facts. I’ll try to get my hands on Hoadley's book and do a search for Al Carrut for more input. It will be very interesting reading I totally agree with you on the use of CF. I use it all the time for the same reason Well, looks like we pretty much agree. I honestly haven't looked into the strength differential between flatsawn and quartersawn wood in any great detail, simply because both have proven more than strong enough (several million fender clones can't be wrong), but since I like a bit of extra stiffness and a bit less memory effect, in comes CF. I'm planning on laminating a bit into my X-braces for my next acoustics for the same reason (memory effect, not strength). Whenever I see people using quartered wood because it's inherently stronger, or thinking that simply resawing and flipping the center section of the neck (ie, ANY lamination) will automatically result in a stronger neck, I just wonder what that's based on. More dimensionally stable, yes. Less likely to warp, yes. Stronger? Not necessarily, and it depends on the selection of woods. Quote Link to comment Share on other sites More sharing options...
Guitarfrenzy Posted January 22, 2006 Report Share Posted January 22, 2006 Interesting conversation here. I had just always assumed that quartersawn was stronger, might have to do some testing on my own now.. lol I do know from my own experience that CF rods strengthens the neck considerably. Two necks that was made from the same flatsawn maple blank, one without the rods can be pushed at the headstock end to make the strings go flat in pitch, the CF rod one takes way more force to accomplish the same result. Don't take my word for it though, try it yourself. Now to do some flatsawn, quartersawn testing... haha Quote Link to comment Share on other sites More sharing options...
Mickguard Posted January 22, 2006 Report Share Posted January 22, 2006 Are CF rods always used in pairs? If one were to use just one, would that unbalance the neck in some way? I'm just wondering... Also, in the thread in the link, Myka spoke about using hollow round rods --seems to make sense...but where do you find them? Quote Link to comment Share on other sites More sharing options...
bugman96 Posted January 22, 2006 Report Share Posted January 22, 2006 If flatsawn is stronger in one thickness I cannot se how it would be weaker in another thickness. I agree, but I threw it in because it's an alternative hypothesis you have to consider if you're going to do some experiments IMO. Back to the thread! Quote Link to comment Share on other sites More sharing options...
Mattia Posted January 22, 2006 Report Share Posted January 22, 2006 You can use one, but I'd balance it out, instinctively. The tension doesn't vary too hugely along the neck, so better to have it evenly reinforced, or near as possible. Round tubes can be used, and provide less strength than a square rod of about the same size, but are lighter. If I come across a neck structure I start using that ends up being too stiff for my liking with the CF (say a mahogany/rosewood/maple/rosewood/mahogany laminated neck), I may give it a shot. I've got some CF tubing for making flying buttress braces; Kite supply places like intothewind.com have 'em. Quote Link to comment Share on other sites More sharing options...
akozols Posted January 23, 2006 Author Report Share Posted January 23, 2006 HI, Just a quick update and quick clarifiacation. Even though I'm knowledgeable about all aspects of guitar repair, I'm a total newbie when it comes to wood and woodworking. My woodworking tools consist of a cope saw, rasp, and a router that my wife got me for christmas. My shop is a little table I have down the basement. If it's a messy job, I have to go outside in the cold. But I still learn more each day. BAck to the original problem. I went back and looked at the original neck. I noticed all the wobbiness was from from the 5th fret to the nut. That's were the neck tapered down to 1 5/8" width. On the back of the neck in that area are two "V"s in the grain. it doesn't look like a glue-in spot. It almost looks like the grain is coming in at a different angle. Is that the cause of the wobble? Is it because the profile is different in this area? thanks, al Quote Link to comment Share on other sites More sharing options...
akozols Posted February 13, 2006 Author Report Share Posted February 13, 2006 I finally got around to finishing my project. It didn't turn out to bad. I rushed the cuts so it wasn't a perfect fit. I filled the gaps with a mixture of mahog dust and glue. The dried mixture cured darker than I wanted. I got the chunk of wood from soundat11 and he sent me a piece that would match(it did). Overall, it was a good fix to get it up and running again. al Quote Link to comment Share on other sites More sharing options...
edslides Posted February 13, 2006 Report Share Posted February 13, 2006 Im going to make my own mahogany neck soon. How thin is too thin? Perhaps you could have reinforced it with some of those carbon fiber rods that they sell at Stew Mac. Ive got some flatsawn mahogany that I plan to use for my neck. I plan on using a nice sturdy truss rod and two carbon fiber rods on either side to reinforce it. I dunno, maybe Ill end up trying to get some quarter sawn...Ill just see how this works out first. i had the same thinness problem because i let someone else cut out the neck profile who had better tools but thought the cut lines clearly marked in fine lined ink wrer a mere suggestion and cut it 5/32 too thin. i added a 3/16 thick piece of maple to regain the thickness, routed for the truss rod and put on a maple fret board [url=http://photobucket.com/albums/f302/edslides/?action=view¤t=000_0526 cut and pste this link to see. notice the mahogany-maple-mahogany laminate for the neck thru. this seemed to work so far. time will tell. Quote Link to comment Share on other sites More sharing options...
Setch Posted February 13, 2006 Report Share Posted February 13, 2006 Those V shapes are the flatsawn grain. In flatsawn timber annular growth rings are slice through, and create shapes which look like contour lines. In quartered wood, the growth rings are not visible,since the cut runs at 90 degrees to them. If you cut an onion, you can see the same effect - I'll put one in my lunch, and take some photos to put up here later. Quote Link to comment Share on other sites More sharing options...
SoundAt11 Posted February 14, 2006 Report Share Posted February 14, 2006 Cool! I'm glad you've got it fixed and playable. Good job with filling in the missing neck joint. That color match looks good from the photo. Quote Link to comment Share on other sites More sharing options...
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