elderthomas Posted January 19, 2005 Report Posted January 19, 2005 Recently I finished a Millanola model using Engelmann Spruce for the top. I graduated the top to about 2 mm as indicated on the Strad poster. The results were a deep hollow sounding instrument. To try and improve it I replaced the bass bar with a heavier one angled more across the grain. This resulted in some improvement (a little brighter) but still not a pleasing sound. I am now starting on another similar model. This time I am using some spruce obtained from SVS tonewoods. It appears to be nice wood with a density of about .4 gm/cubic centimeter. However, I find that as I am graduating the top, at about 3mm thickness the tap tones are already becoming lower than I think they should be, mode2 about 155 Hz, mode5 about 330 Hz. The feel of flexing the wood also makes me think that I should not take it any thinner. I was wondering if anyone has any suggestions, especially on this particular model. Does anyone take the graduations down to the Strad poster specs? Maybe the wood Stradivari used was quite dense. Any thoughts will be appreciated.
Seth_Leigh Posted January 19, 2005 Report Posted January 19, 2005 Richard, did you by any chance use the sethmillonodefault settings in your arching program, to make the arches? I'm wondering if you cross-checked the dimensions I'd entered against the poster and found them to be reasonable. As for graduation, I don't know enough to say anything, but I'm not going to be graduating my Milanollo-patterned 2nd violin according to the poster. I'm going to use the same scheme I used for my first one, with a uniform 2.5mm over the top and a pattern on the back going to nearly 5mm in the center and thinning in an appropriate pattern from there.
Michael Darnton Posted January 19, 2005 Report Posted January 19, 2005 I wouldn't go under 2.5mm for a top, and 2.7 is certainly safer. Why not leave it thicker this time, and see what you think?
elderthomas Posted January 19, 2005 Author Report Posted January 19, 2005 Seth, I didn't use those settings, and I am not sure what they were. I examined the poster, and tried to match the cross archings, with a little extra height near the bridge center to make up for the settling in effect, which I believe must be there. In other words the long arch is not as flat in the center. If you tell me where to find the data you used I will compare it to mine. Michael, Thanks for the suggestion. I am going to leave it at 3mm and see how it does. If need be I can always regraduate it later.
fiddler59 Posted January 19, 2005 Report Posted January 19, 2005 One problem I see is that Engleman is a soft less dense spruce. Thicker graduations are certainly the norm using this type of spruce. fiddler
ispirati Posted January 19, 2005 Report Posted January 19, 2005 Does the spruce top get thinner while aging? Let's say if one graduates a top at 3.0mm today. 100 years later, will the top stay at 3.0mm? or will it go thinner as the wood age?
Wolfjk Posted January 19, 2005 Report Posted January 19, 2005 Hi, -----if one graduates a top at 3.0mm today. 100 years later, will the top stay at 3.0mm?----- It depends on how well the wood was seasoned before you started. If the spruce was seasoned by exposing it to the seasonal temperature changes for 2 or three years the wood might contract only a fraction. However if the wood was ill seasoned it might contract more, but no more than one or two %. Cheers Wolfjk
Oded Kishony Posted January 19, 2005 Report Posted January 19, 2005 elderthomas : >It appears to be nice wood with a density of about .4 gm/cubic centimeter. < with graduations of about 3mm for the top your plate will end up with a weight between 70-80 grams, add to this a few more grams for the varnish and you have a pretty heavy top. It can still sound quite good but response will feel slow (IMO) You can sometimes salvage this situation if your back is light weight. Oded
Craig Tucker Posted January 19, 2005 Report Posted January 19, 2005 "However, I find that as I am graduating the top, at about 3mm thickness the tap tones are already becoming lower than I think they should be, mode2 about 155 Hz, mode5 about 330 Hz. The feel of flexing the wood also makes me think that I should not take it any thinner." Perhaps this is where the problem lies. What takes precedence when you're thicknessing a top? That the tap tones come out "right" for some theoretical norm or goal, or that the plate sounds right in the finished violin? I guess it's a "which came first, the chicken or the egg" sort of thing. I will suggest that free plate modal tuning cannot be relied upon to provide the information you need in order to determine how the plate is supposed to be thicknessed. (or arched) for a particular model/wood combination. In general terms, I have to side with fiddler59 when he says: "One problem I see is that Engelmann is a soft less dense spruce. Thicker graduations are certainly the norm using this type of spruce. fiddler" Softer, less dense, and yet really resistant to bending, Engelmann has to have added mass in order to respond even sort of like (for example) Sitka - more to add the necessary damping to the finished plate than anything else, in my opinion. Still, Sitka (like Engelmann) isn't really the spruce of choice for violins either, is it? So why use either as a standard in this discussion? If I'm not mistaken, the usual ‘spruce of choice’ for traditional violin making is some sort of European spruce (Latin name: who knows? Bruce?), and I'm not really familiar with its peculiarities. Can you expect different varieties of spruce, with entirely different characteristics, to react alike when it comes to thicknessing and arching? And if you can’t, then why would some arbitrary system of tap tones or modal tuning work in the first place? Was the Milanolla violin made with American Engelmann spruce?
chronos Posted January 19, 2005 Report Posted January 19, 2005 Quote: If I'm not mistaken, the usual ‘spruce of choice’ for traditional violin making is some sort of European spruce (Latin name: who knows? Bruce?), and I'm not really familiar with its peculiarities. The latin name is "picea abies".
David Tseng Posted January 19, 2005 Report Posted January 19, 2005 Assume the arch is OK. As MIchael mentioned, I would also suggest that you start from 3mm all over and lightly glued the top on the rib and play it. Then slowly thin it down. I select my spruce very carefully from the saw mills. I have one pile of spruce boards which can be thinned to 2mm and the mode 2 & 5 are still F#.
Jacob Posted January 19, 2005 Report Posted January 19, 2005 "I examined the poster, and tried to match the cross archings, with a little extra height near the bridge center to make up for the settling in effect, which I believe must be there. In other words the long arch is not as flat in the center." I wonder how safe these assumptions are. The question of plate distortion has come up frequently in past threads, and I got the impression that the top rises rather than falls over time. The heights of the cross archings on the Milanollo poster don't agree the the heights on the longitudinal arch, but I'm not sure that either the heights of the cross-archings or of the longitudinal arch, where these intersect, are necessarily the most "original". What I did was to try and make sense of past discussions of plate distortion to understand where to expect distortion. I'm taking this from memory, but the longitudinal arch is just about the same height as cross arching #3, whereas it is appreciably higher than cross archings #1 and #5 - which accounts for the "flat" appearance of the long arch. The first Milanollo model I made reflected the long arch as on the poster, and the violin did not look as good or work as well as the next one, where I paid more attention the effects of plate distortion on the poster arching guides, and made adjustments to the arching templates where appropriate.
Michael Darnton Posted January 19, 2005 Report Posted January 19, 2005 A problem with matching long and cross-archings is that usually a violin of this age is distorted so that the plane of the ribs that everything should be referenced to isn't a plane anymore and twists every which way. Usually the corners are low relative to the ends on the top, and high relative to the ends on the back (collapsing of the body under tension), which lowers or raises the cross archings relative to the long, which is referenced to the ends, not the sides.
Jacob Posted January 19, 2005 Report Posted January 19, 2005 That's exactly what I was imagining, and what I kept in mind when re-constructing workable cross-arches as well as a realistic long arch. Essentially - but not exclusively - that led me to the conclusion that most of the re-calculation of the longitudinal arch heights is required at the cross-arch heights of #1, #2, #4 and #5, with the largest departure from the poster heigths at #1 and #4 (in the case of the Milanollo poster).
elderthomas Posted January 19, 2005 Author Report Posted January 19, 2005 Jacob I find on the poster belly arches the long arch and cross arches only agree at the lower corner (16 mm). The lower bout CA=14, LA=12.5, Cbout CA=15.5, LA=16.5, Upper corner CA=15, LA=16.4, Upper bout CA=12.5 LA=13.5. I guess they have to measure the long arch relative to the ends in order to have this kind of discrepancy. What I actually did was adjust the heights as close to the cross arches as I could to get a reasonable looking long arch. A little less flat than the poster long arch. The highest point being 16.2 mm at the Cbout. ctviolin, I am aware of the controversy about mode tuning. I am not necessarily trying to match the modes to specific values on the front and back. However, being an inexperienced maker, I don't have much of a feel for where I am during the graduation process. So I use the tap tones as a kind of bench mark, As I believe some makers use flexing of the plates as one measure of when the plates are at the right thickness. I also flex but don't trust my feel for it completely. For the 8 violins I have made I seem to see relation between getting a hollow tone and getting the top thinner than 2.5 mm. I believe arching has something to do with it also, but I have made different archings and the thickness effect seems to prevail. I guess I am like the blind man trying to identify the parts of the elephant. I will have to feel enough elephants to eventually learn what parts are what. It may be that what I refer to as a hollow sound would be pleasing to some, if it isn't too exagerated, but I don't care for it. David, I am probably going to do what you and Michael have suggested.
chronos Posted January 19, 2005 Report Posted January 19, 2005 Quote: ... start from 3mm all over and lightly glued the top on the rib and play it. Then slowly thin it down. When you thin down the plates on a white violin, do you pry the top off and thin it down from beneath, or do you perhaps leave the top on, take off the fingerboard and thin it down from above? [if the question seems naive it's because I've yet to make my first violin]. What would be the advantages or disadvantages of thinning down the top from the outside after having established the overall desired thickness from beneath? The way I see it, to thin down the top from the outside while keeping the "same" arching you'd have to either lower the thickness over the entire plate or else lower the height of the plate within and including the fluting. Either way the result (as I imagine it) seems different from what would happen if you alter the thickness from beneath the top without thinning down the edge. Either way, the idea of adjusting the arching and/or graduation according to the character of the assembled violin seems to hold a lot more promise than the idea of tuning the free plates. What do you guys think?
Seth_Leigh Posted January 19, 2005 Report Posted January 19, 2005 I think that if this is your first violin you'd be better off just picking a "reasonable" graduation plan and then executing it, and letting it be what it's going to be. I say this because I really don't think you'll have the experience to know what to do each time you take it apart to "tune" it, or know when to stop. I think there's enough on your plate just making a violin at all without trying to do what you're saying. Just my $.02. I was swayed immensely when I was reading up before my first violin by the arguments of folks like Michael and others who said they know people who do plate tuning and other kinds of tuning, and in their opinion they weren't making better violins than other competent luthiers who weren't doing those things. I got a special chuckle reading once where Michael said he has luthier friends who carefully note the tap tones of each plate as they finish it, record it in their book, and go "hmm".
elderthomas Posted January 19, 2005 Author Report Posted January 19, 2005 I've never thinned a top after closing the box, but I can imagine one problem with trying to thin it from the top might be that you can't measure the thickness with the box closed. It would be hard to tell how much you are removing.
ispirati Posted January 20, 2005 Report Posted January 20, 2005 I look at the plate "tuning/graduation" method arguement differently. Some people use frequency (tap tone) as the measurement; others use weight or mass as the mesaurement. But the ultimate goal is CONSISTENCY, or at least, a method to control the output of the final tone consistently. Both methods have the same goal. If we want to measure the amount of water in a glass, how can we "measure" it? 1. How many fl Oz, or ml? (ie. by volume) 2. How much does it weight? (ie.. by mass) 3. What is the tap tone? (ie.. by frequency) These are probably the most common methods that don't require expensive specialized instruments. If you have the 2 identical glass with same amount of water in them, you will get the same mass as well as same tap tone. Well.. we know water is relatively consistent in density. But wood is not. Therefore mass and frequency are more valid to be used as measurement. Since violin is an accoustic instrument, it is natrual for some violin maker to measure the amount of wood by frequency rather than mass. Ultimately, the goal is the same. How much "wood" is in the plate, and how they are distributed. Is there anything wrong with this logic?
fiddler59 Posted January 20, 2005 Report Posted January 20, 2005 You can measure the thickness and thin with the box closed using a Hacklinger caliper. fiddler
Seth_Leigh Posted January 20, 2005 Report Posted January 20, 2005 If you're "tuning" it, rather than graduating to a number, then in theory you don't really care how thick it is. The trick is knowing which changes to make to effect what improvement, and when to stop. I remain unconverted to any particular scheme, but someday I may have accrued enough experience to have an opinion.
chronos Posted January 20, 2005 Report Posted January 20, 2005 Quote: It would be hard to tell how much you are removing. If you thin down the top while ensuring that it remains consistent to the desired arching, wouldn't the overall thickness be reduced equally accross the area being thinned down? I'm more concerned with whether it's a bad idea to thin down from the outside, and -- if it isn't -- whether one should do this across the entire plate (including the edge), or stop at the fluting (thus leaving the edge as thick as before).
chronos Posted January 20, 2005 Report Posted January 20, 2005 Quote: I think that if this is your first violin you'd be better off just picking a "reasonable" graduation plan and then executing it, and letting it be what it's going to be. I say this because I really don't think you'll have the experience to know what to do each time you take it apart to "tune" it, or know when to stop. I think there's enough on your plate just making a violin at all without trying to do what you're saying. Just my $.02. I don't disagree with you, but I'm thinking toward the future. I'm curious about David's approach to thinning the plates, as thinning down the plates and judging the way this affects the assembled violin is something I'd like to try out at some point. It's just a question of which approach is better in such a context.
Seth_Leigh Posted January 20, 2005 Report Posted January 20, 2005 I hear ya. Far be it from me to discourage someone from excercising their noggin. It's healthy to think about, but doing it on your first instrument is another matter. I just remember Dr. Goddard's first liquid-fueled rocket. It looks stupid, but it was his first. They didn't get around to making the Saturn V until later.
ispirati Posted January 20, 2005 Report Posted January 20, 2005 Seth... in order for you to accrue plate graduation experience, you need a consistent method of measurement. My point was that you cannot use volume (thickness being the flexible dimension) to graduate a plate and produce consistent results. The density for each piece of wood is different. How do you measure the amount of wood in your plate will end up being your own method of graduating your plate. Currently, I try to do both mass and tap tone just to keep track of both set of data. The thickness is only a reference starting point and an indication of distribution of mass. If you simply follow thickness only, then each piece of wood would end up with dramatic different results. At the same dimensions, the mass and tap tone would be different for different pieces of wood. Personally, I am have not attached to any method. I am also accruing my experience as well. But I find it interesting to see people fighting over tap tone and mass distribution methods. To me, they are the same thing. It is like one person says "There are 355ml of water in that bottle!". The other argues "No.. There are 12.5 Oz. of water in that bottle!". In reality, they are the same. They just measure the water differently.
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