estebanana -> RE: Action measurement (May 1 2017 3:47:35)
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1/32 inch equals 0.79 mm. So where would that get us? A normal mid line Martin action @12th fret under bass string is 4/32nds - ish - See you just do the whole thing in inches or decimal inches. Scientists don't work in inches, but the American steel string industry was based on the inch system, and so was pattern making and machinist work, and still is. The decimal inch is a system you already use, fret sizes were until very recently measured in decimal inches. Spanish guitar making is also based on the inch system, but it was lost in the probably the 1970's - The Ramirez shop up until at least 1960 was in part using an inch system. Metrication came later to Spain than it did to the Northern countries in about 1868 give or take a few years. However there were several industries that did not convert to metrication until well into Franco's era. There are some interesting social, political and industrial reasons for this. The guitar, the Spanish guitar anyway is conceived in the inch system it's base of measurement being a yard stick. The guitar is laid out in ratios that work out in inches. Any you don't want me to get into all that, it's esoteric stuff that people don't care about, but just look at bridges. they lay out in ratio 2:3:2 - 2" of wing or arm. three inches of saddle width, and then 2" of wing for a total of 7". Fingerboards lay out on a ratio too, which is roughly workable in inches- Think Torres dimensions. 2" at the nut- String to string at saddle 2 1/4" to 2 3/8 " wide - then look at fingerboard width at 12th fret join it is the same 2 1/4" to 2 3/8" There's a layout which works in rounded off inch decimals. Different scale lengths have bases in inches ans in metric measurement, but that is too far out to analyze without losing a lot of people. I got off the topic, but guitar ratios are grounded in inches, the metric system was overlayed on the guitar later when metrication became a trade standard. I did a lot of research on this and checked it out with a couple guitar historians and it's really a thing. Guitars are documented today in the French metric system, they were basically conceived of in inches. There is some history between Spain and France prior to Torres and others inventing the modern version of the guitar, there was the war between France and Spain, which deterred the rapid adoption of the metric system. The factions in Spain were roughly half nativist 'Majo- Maja' who sympathized with all things Spanish and the 'Afrancesados' who were politically inclined to to French Enlightenment revolution as a model. The metric system came with the French Revolution and there was push back in Spain because it was associated with France and the Lowlands, who were enemies. By the time we get to the 1860's, there is still populist -nationalist social resentment of French culture and technology, but the metric system is nonetheless introduced. Tradesmen were slow to adopt metrication because it was not required to do their work, one could build a house just fine in the inch system which was in place. And the kicker is that the best tools were coming from Sheffield England and if a tradesman like Torres could get an English plane and saw, or English chisels he was going to get an English steel ruler marked off in inches. Maybe decimal inches. If not then in foot rulers and yard sticks. English tools were the gold standard of tools. And Spain was largely feudal in rural areas until early to mid 20th century, and if a craftsman did not have access to coveted English tools how did they establish an accurate system of measurement? They were not really in the era of metrication yet, like say a medical doctor in a metro area would have been. They copied rulers that perhaps one established journeyman had and they made their own rulers by ticking off inches onto a piece of lath with an ink pen or pencil or knife. And they made wooden wedge stops and wood shim gauges which were calibrated to increments of whatever they wanted. 1/8 th's inches, 1/4"s, feet, yards, or even long cloth tapes or cords knotted or marked off in feet and half feet. They used gauges and measuring tools they made themselves, eventually Spain metricated fully across the spectrum of trades, but guitar making was one of the last specialty trades to convert. And maker by maker that happened between the 1920's and 1950's, my best guess is more towards the 1950's. So basically your eyeballs, feeler gauges and graduated wedge stops are muy tradicional for making the Spanish guitar. I use the rulers and inches because I worked in a shop ran by an iron fisted Jew who learned pattern making in high school from Yankee machinists who used decimal inches. Which is also tradition. So everyone is correct, and the player says "Ahhh, just right." when the action suits them, and they really don't care about the actual numbers on our wedges or rulers. --------------------------------------------------- Here's a page from one of my log books in the steel string shop: On the left you see I worked out rough numbers for a neck reset in millimeters, and on the right making a new saddle and roughing out the goal fractions of an inch. I use both measuring systems at the same time depending on task. I think most American makers do that to some extent. I also use feeler gauges, blocks of wood, wedges, filed depth stop marks and any other rote or haptic measurement trick I can get my brain to understand. The saddle chart was a notation on how the existing saddle was compensated I take notes on that one in a while to remember how a particular steel string saddle looked so there is a record and a goal to follow when compensating a new saddle. That is getting a bit picky, but in the beginning I did that and learned a lot from it.
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