Official Luthiers Forum!

Hey Michael, is that a cittern or english guitar for your avatar? Did you make it? Give the gory details.
Tanks! Tanks a million!

Welcome to the forum Michael !

Watch out for Hesh - He bites!

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

Old Smiley, where'd you find him?

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http://www.dickeyguitars.com

Tommy - It's a Portuguese guitar - Lisboa style. I didn't make it, but bought it in Lisbon a dozen years ago.

I suppose it's all a matter of perspective. Growing up with the metric system I couldn't imagine anything else. Converting between the two has become second nature but if I'm estimating something or picturing it in my mind's eye I'll always think mm/cm/m/km.

Plasterboard (aka sheetrock, aka gyprock, aka drywall) is sold here as 1200x2400mm (4'x8' but not referred to as such) so shouldn't be too difficult to calculate what's needed for your 4200x4300 shop without needing to convert either.

All this said, I build guitars in inches and generally think of them as such, but I'll generally do so in decimal inches rather than fractions... if it's a fraction I'll convert it to decimal and proceed from there.

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Richard
http://www.guitarmaker.com

Talleyrand, Rick. Talleyrand.



I use decimal inches, seems perfect for guitar building. I almost forgot metric measurements (by eye) though. The genius of the metric system really is the decimal thing.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Tommy, I don't know if you realize, but your question stirred up a discussion that is as old as gets around here (and I don't mean since the introduction of the new software!). We still enjoy going at it again and again though, sort of like telling the same old fairytale over and over, but with slightly different twists each time. Think about it people, if not even Napoleons defeat in Russia was enough to put the metric system out of its misery, that should be a lesson for you all...

Rick, rooms are usually measured in meters in normal speak, so you have a 4,2 x 4,3 m room and sheet rock are 1,2 x 2,4 m (at least here in Europe), so it really shouldn’t be too hard to figure it out.

It is standard practice in most countries on this planet in manufacturing to specify every length dimension in meters, millimeters and micrometers only. Being a factor of 1000 apart, there is close to zero probability of mixing these up. We also use centi, deci, deca and hector prefixes in common use, and the only time I hear anyone finding it hard to decide where to place the decimal in the number for a measurement of an object is from people who had to learn the system as a ‘second language’, that is some English speaking countries. If you know the system like you know your first language the issue does not come up.

Sometimes you hear the argument that the numbers in the metric system are not intuitive enough (unlike inches which are related to the familiar proportions of the human body and therefore self evident I guess) and that the units are either too short or too long. In normal use, we just add another decimal if we need more accuracy, and that’s that.

I think it is an advantage of the metric system that we never have to consider whether a fraction or a decimal number is appropriate, but that is probably not much of a problem if you learn how to think in imperial units early on, like most of you folks.

I actually think the discussion is quite silly, it’s like discussing whether the English or German (or perhaps the Japanese or Swahili?) language is best suited for technical terms, and which one will give you the highest degree of precision.





I used to cut the frets by hand, and I have used both 645 mm and 650 mm scales. Now I use an imperial template from Stewmac and a simple sled on the table saw... The humiliation never stops!

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Rian Gitar og Mandolin

Frankly, all these touchy-feeling 'human measure' arguments are pretty silly; SI, Imperial, it's all based on a fairly arbitrary defintion. We set a standard, we use it. The divisibility factor is the only minor advantage imperial measures have (divisible by 2, 3, 4, as opposed to just by two without getting decimals involved), but it's not like I find a whole number to be 'easier' to deal with than a decimal...

I grew up in metric, so it feels entirely natural to describe the size of a room in metres, or to say I'm about 1.8 meters tall (rather than 6 foot, which only means something to me in terms of distance because I know that's my height, which is 1.8 meters...). Half mm? Plenty tiny. And marking quarters of those is easy enough, and for the rest we have dial and other calipers.

I think of certain measures in imperial, because that's how I communicate about them (25.5" scale length, 16" lower bout, that sort of thing), but I don't have a firm mental grasp of imperial sizes that I can't relate to very specific dimensions on (say) a guitar. But I lay everything out (plans, dimensions, etc.) in mm, although I have calipers and rulers for both systems. The one we understand is the one we're most familiar with, but objectively the ease of conversion and measurement with mm and my familiarity with them makes it my first choice.

Is it weird that I actually like fractional inches? I find them so much easier when having to divide by halves or thirds.

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Joe Breault
Merrimack, NH
Perpetual novice

Joe, it's not only weird, it's sick!

But hey, whatever gets you through the night


<edit> Sorry, that was dumb. I can understand it, as long as that is what you're used to what could be more natural?

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Rian Gitar og Mandolin

No worries Art...I know I have issues

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Joe Breault
Merrimack, NH
Perpetual novice

I worked for a surveyor for 6 years back in the late 70's. The old timers worked in rods, chains & links.
That's how most of the U.S. was layed out back 200-250 years ago.

0.66 foot (ft) = 1 link (li)
100 links = 1 chain (ch) = 4 rods = 66 feet
80 chains = 1 U.S. statute mile (mi) = 320 rods = 5280 feet

Pretty cumbersome.

We just converted everything to feet and decimals of a foot. 1/100 of a foot being the smallest unit (about 1/8").

So, a 25.4" scale would be .1282828 Rods....

Good luck.

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Horton, MI

One important aspect of using different measuring systems is that the size of many things is somewhat arbitrary. So things are designed to use convenient measurements is the system that is being used. 645mm is very close to 25.4" but it is not exact. If you are building in Imperial units, you choose 25.4. If you are building in metric you choose 645mm. No player on the planet could tell the difference between the two scales. There are other measurements that have greater differences. If you design a guitar the is similar to a guitar with a 16" lower bout, do you choose to make it 406.4mm? Probably not. You might choose 406mm if you are copying and instrument or 405mm if you are just trying to capture the feel or even 400mm if you figure that half a centimeter isn't really important.

Airbus narrow body planes a slightly wider than Boeing's because of the measurement systems used to design them. This slight difference which is just a few inches, is noticeable by passengers and many find Airbus planes more comfortable.

That's right Mike. That's why studs in our houses are spaced 600 mm apart, which is real close to your 24", our sheet rock is 1.2 x 2.4 m and so on. When I design houses (I am an architect) I work hard to make every measurement (in millimeters of course) on my plans end with either a 0 or 5. It just makes it easier to keep track of things for everybody.

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Rian Gitar og Mandolin

like the other engineers here, it really does not bother me one way or the other what unit of measure I use because I have to use both and others day in and day out. i will say any base 10 increment is more intuitive in use. be it inches in decimal places or millimeters in decimal places

The one claim I have to debunk is that one unit of measure is more accurate than the other. That is really a short sided and not true. All linear units of measure can be carried to equal accuracy. It is just a matter of how accurate you chose to measure to with a specific unit of measure . Or in other words how many decimal places you chose to measure to.

Even in setting manufacturing tolerances one unit of measure can be as accurate ans the other

Hi Michael,

I'll offer a slightly different answer: buy a fretting template for the scale length you want to build. Stewart McDonald and LMII have them. That will be very useful for the neck and fret layout, and bridge/saddle positioning. You can easily make a miter box with a pin that will index in the template slots, and then with a fret saw you'll have all you need to make an accurate fretboard. After you have completed the glue-up of the bridge, using the template again to assist in finding the uncompensated saddle location, then you can decide if you want to build more guitars. If you do, keep the template; if not, sell it for at least half price on Ebay. The fretting template will be a lot easier (and almost undoubtedly more accurate) than hand measuring frets, and will give you peace of mind throughout the build process, to ensure that your guitar will be able to play in tune.

All of the other measurements on the guitar can be done with your regular 'ol tape measure, but (as mentioned), an inexpensive ($20?) dial caliper is a smart buy if you don't already own one, and a small (6" long), inexpensive machinists ruler graduated in 64ths or hundredths will come in very handy for the nut, bridge, saddle, and in setup of string (action) height.

Those who think in metric may disagree, but it seems to me that if you plan to build a classical guitar you had better have metric measuring tools, and if you are building steelstring guitars, you will probably want imperial measuring tools (because most of the books, DVDs, plans, and examples you follow will be fractional inches.) Not entirely true (especially outside the US), but I think generally true in the US.

Good luck, and have fun!

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Sorry, my first post was directed at Michael who started this thread, not Tommy.

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Rian Gitar og Mandolin

It doesn't matter what you use, as long as everyone around you is using the same system. Whatever you find ergonomic or fluent.

And of course, I've seen the 25.4" Martin scale tossed in a few times for example. I know most folks know, but this number is still a pet peeve of mine, as of course Martin has never made a 25.4" scale guitar. I have a silly notion that 25.34" scale should be called and 25.34", not 25.4". Seems trivial, but I've seen guitars made where the frets were spaced from a 25.4" template (that was actually a true 25.4") from one supplier, while the bridge was located using a 25.4" template from another supplier, who of course didn't really mean 25.4", but of course the 25.34" scale that we all call 25.4". Huh??

Measurements matter most when trying to communicate with others, and even here, very few measuring devices are totally objective. If I'm building a shed, I find it not only important to use the same tape measure for all critical measurements, but to have the same person do all the readings and markings. Two people can and often do read the same measurement quite differently.

I prefer to measure everything in parsecs by the way, so my specs generally have to be written to about as x10 to the -20th or so power. The rulers are a little long and cumbersome, but it makes for easier communication with luthiers on other planets.

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Eschew obfuscation, espouse elucidation.

You are describing limitations of an instrument of measure, not a unit of measure. Yes the manufactured limits of a given instrument of measure may be at a higher precision level. But that is the limit of the instrument not the unit of measure, IE mm vs inches. 1.0000mm is no more accurate than .039370inches. they both describe the precisely the same thing. Once again an instrument of measure can be more accurate than its given counter part, but not the unit of measure its self. Yea! I know i looking at this from an engineering point of view and not a woodworkers point of view. But none the less it is true any given unit of measure can be as accurate as any other. Like I said it all a matter of how precise you chose to be with that unit of measure.

OK, OK! I think the only way to settle this is to convert to cubits.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Nah....Cubic furlongs per fortnight is simpler than cubits! If you used cubits you'd need to convert your prices to shekels since cubits are strictly Old Testament. And we're not building arks here.

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Hank Mauel

Hi Michael P,

Did you mean to quote me? I agree with everything you're saying, but don't see that I said anything about precision. I was trying to give a beginning luthier some practical advice.

Or, if you did mean to quote me, is this the line you're referring to: "The fretting template will be a lot easier (and almost undoubtedly more accurate) than hand measuring frets..." My reference to accuracy is the ease of laying out the fretboard accurately, and the greater likelihood of error if someone were to do the fret layout using a ruler.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I miss read the first time but left the post anyway sorry about that

No harm, no foul, Michael. I just wasn't sure if you felt I was giving bad advice.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia