Why Millimeters?

As you read through my articles, or in buying plans from Georgia Luthier Supply, you will notice that just about everything concerning measurements includes both inches/fractions and the metric equivilant of millimeters.

As an architect by trade, for more years than I can remember, I eagerly awaited the onset of metric measurements for the building trades. As it turns out, the change never came. There was simply too much resistance for change, too expensive for change-over, and too many other excuses that I don’t ever want to remember.

Why do I prefer the use of metric measurements you say? Well, at least in my case, I find that a metric measurement is much easier to remember, easier to measure and is a breeze for math. By math for instance, I mean if you measure the distance between the 1st and 6th strings and want to make 5 equal divisions for the other 4 strings. In this example, let’s say you measure 40 mm and want 5 equal divisions? 40/5 = 4 mm. How much simpler can you get than that? I mean otherwise you would have 1-9/16″/5 = ??? Yuck – you see what I mean?

Purchase A Few Good Steel Rulers:

The key to your success will be in the purchase of good quality stainless steel rulers that are accurately marked. I keep several sizes in my shop:

6″ or 150mm: I use this for conveniently measuring smaller items on the headpiece, fret spacings, nut, saddle etc. Make sure it is graduated in 1mm and .5mm increments.

18″ or 450mm: This is my favorite rule. It easily meets about 75% of my measurement needs for bracing, guitar width and length, neck length and much more.

36″ or 900mm: This rule has one major job and that is measuring the scale length, and I reserve it mainly for that purpose, although I do use if to measure larger items in the shop as well. But for the really larger measuring jobs, I keep a mm retractable tape.

Getting Your Feet Wet:

Not accustomed to using metric measurements? Here are a few hints that will get you going.

If you are confused by the terms millimeters (mm), centimeters (cm) and meters (m)? This is really quite simple. For instance :
26 inches = .6604 meters
26 inches = 66.04 centimeters (factor of 100)
26 inches = 660.4 millimeters (factor of 10)

In my guitar shop, we will very seldom use meters or even centimeters. Millimeters will be the measurement that we use most often.

The Conversion to Metric Measurements:

If you encounter a measurement of inches and fractional inches here is what you do – by the way, make sure you have a calculator.

You will want to convert the fraction to a decimel number. In the example you have a measurement of 21/32″ simply divide 21 by 32. This equals .65 inches. Now add the inches to the number. If that is 6 inches, for instance you would have a number of 6.65″

Next to convert to millimeters, just multiply the number 25.4 x 6.65 and that equals 168.91mm. The number 25.4 is the exact number of millimeters equal to 1 inch.

Usually you will not have to go through these difficult conversions, especially with all plans that come from this site – you will get both millimeters and decemil inches.

GLS Tip #1: For quick conversions you can just multiply 25 x inches and get quite accurate results. Example 6.5 inches x 25 = 162.5 mm

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