Official Luthiers Forum!

Hi gang - first post here, so a brief intro before I launch into my question. I've been an amateur sawdust-maker for years, and play several instruments badly. I've recently decided to try my hand at building a guitar, and will begin as soon as I get my workshop set up. I've recently moved to Johnson City, Tennessee, and am in the final throes of remodeling my house, including a new workshop in the basement. I've been lurking here for a couple of months, and reading everything I can get my hands on about guitar building. I'm anxious to get started!

So, my question: many of the dimensions I've seen for stringed instruments are expressed in tenths of an inch, for example, scale lengths. How do you measure this? Do you have a rule that is divided into tenths, or do you convert to metric, or 64ths?

I know this is a very elementary question - I'm sure it won't be the last!

Thanks in advance,
Michael

Look for a ruler with a 16r scale:

No. 16R – Quick Reading 32nds, 64ths, Aircraft Quick Reading 50ths, 100ths

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53% of all statistics are made up on the spot
http://driftwoodguitars.blogspot.com/

And welcome to the forum!

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53% of all statistics are made up on the spot
http://driftwoodguitars.blogspot.com/

Welcome Michael,

To measure these small increments (less than one inch) I like to use dial calipers. These calipers are useful for many types of measurements around the shop: measuring thickness of bindings, tops, backs, bridges, etc...

Hope this helps, fire away with more questions...

I use this link quite a bit too, you can convert to mm which I find easier for those close tolerances.

http://buildyourguitar.com/resources/fr ... rptclc.htm

Welcome!

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Burton
http://www.legeytinstruments.com
Brookline, MA.

Learn these eqivalences by heart: 1/120=.0078125, 1/64= .015625, 1/32 = .03125, 1/16=.0625, 1/8=.125, 1/4=.25, 1/2=.5 If you know these you can multiply as needed

Example 3/64= 3x.015625=.046875

it is really simple 1/10=.1, 1/100=.01, 1/1000=.001. It is just a base 10 unit increments

Also Sterritt make machinist scales that are divided in 10s, 100's and 1000s of an inch. You really should also invest in at least a 6" or 10" dial or digital caliper and a indexing dial micrometer with a magnetic base. As you probably know these tools display in decimal of an inch or decimal of a mm units depending on which you buy and some digitalis will display either.

Now with all that said in guitar making, some but relatively few things need a tolerance tighter than +or- 1/64" most will fall in the +or- 1/32 range or greater. A notable exception to that statement is scale length, compensation top, back and side thickness.

In my opinion It really does not mater which unit of measure you use MM or inches you will need to have scales and other tools that are in 10s, 100s and 1000s of the desired units if you use mm 10s is likely as small of an increment as you will need 99% of the time in inches will often need 100s of a unit and even 1000s of a unit. Both units can and do allow the same tolerancing. It is just a mater of how far you carry the decimal place out to.

I've gotten to where I measure almost everything in decimals. It's so much easier. Easy to get "close enough" on center points too. Just get several rulers that are fractions on one side and decimal on the other. (Also be sure to get a digital readout caliper) I also printed a chart of fractions to decimal conversion and taped it to my shop wall. You'll use it all the time.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Hello and Welcome Michael. It depends on what i'm doing but in the case of decimals for scale length (per your question) I convert to the nearest 64th of an inch. Good luck with your shop.

Go metric, and all your questions will be answered and the clouds of confusion will lift!



Really, nobody would ask that question here in the metric part of the world.

<edit> Oh, and welcome!

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Rian Gitar og Mandolin

Welcome Michael!!!!!

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Ann Arbor Guitars

Learn to work in either empirical inches or metric. it is cool to be Bi-incremental

It really does not mater mater if you are using metric, empirical inches or some other unit of measure they are all divided in either fractions or decimal increments. it is just a mater of knowing the the equivalent of one unit, one tenth of a unit, one one-hundredth of a unit and one one-thousands of a unit.

I could make up a new unit of measure called a "Payne" That one unit is equal to (lets say) 3.98 inches

1Payne=3.98"or 101.092mm Therefore 99.8754payne=397.504092" or 1582.06628616mm. It is just a matter of assigning a value.

I was gonna say something about the Payne system, but decided that would be rude!

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Be nice now Waddy

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Being a metric person myself, I had, (and still have) several head-scratching moments. I found it easiest to get a good digital caliper (~$50) that coverts the measurements back and forth. Plus I also have a very good centre finding ruler a friend of mine gave me that has 32nds, 16ths, and inches broken down into tenths.

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Jamie M

Yeah, we were supposed to go to the Metric system 25 years ago.
It didn't quite take, so now were are stuck in the middle using both Imperial and Metric. Now that's a REAL PAIN.
I just convert all fractions to decimal. So much easier to work with.
It'd be nice if everybody used the same system. Metric would be fine with me.
Get yourself a couple good Starrett scales and some calipers like Michael said. I use my dial calipers all the time.

Cheers

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Horton, MI

humm i guess it is because I have worked with so many different units of measure over the years but once I gave up trying to thinking of empirical inches or metric as being physical as in lay your hands on type object and started thinking of them rather as assigned values the conversions are simple 1" = 25.4mm therefore 1mm = .039370 inches. I guess I have worked in engineering and machining too long but to me it is just the mater of knowing the conversion value and as far as fractions is concerned they could be used in metric as well if desired 1/4mm would be .25mm or .0098425 inches It is all a mater of multiplication and division. It is when we try to over think the difference that we get confused. Besides you can always buy a scale that has both units of measure side by side or a t least on the revers side

Thanks for the kind words of welcome, and for the good discussion on measuring techniques. I guess I'll have to replace the old rust-encrusted vernier calipers (accurate to within 1/2 inch!), and get something better than the old fabric-store yard stick that I beat the dogs and children with!

I'll be thinking about building some kind of side-bending apparatus over the next couple of weeks - I may be back for more questions soon!

It's nice to meet y'all. I think I'm going to like it here!

Michael

You're right Arnt. I love metric, it is so much simpler and not so confusing. BTW Arnt, do you have 25.4" fretboard scale laid out in metric? That would be cool!

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"After forty-nine years of violin building, I have decided that the search for a varnish is similar to the fox hunt. The fun is in the hunt."
Jack Batts Maker and Repairer of Fine Violins

I degree!

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Well I can't go home so...... A special present to you all from Billy and I......

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Ann Arbor Guitars

The metric (SI) system was a French imperialist plot shoved down our throats by Tallyrand and Napoleon. The defeat in Russia should have put an end to it all, but no... I don't know how the French got the English to go for it... And that was just a few years ago. And the very basis for the length of the meter is wrong! The French surveyors got the circumference of the earth wrong...

Read this:

http://lamar.colostate.edu/~hillger/origin.html

Convenient metric measurements are either too large or too small for my taste. How's this...my new shop in Tasmania is 4200 millimeters by 4300. So how many piece of sheetrock is that? Yes, they still use 4' x 8' pieces of sheetrock.

I prefer decimal inches in thousandths. I'm reluctantly reasonable with small metric measurements under a quarter of an inch... And I do know that to be 6.35 mm, so an inch is a little over 25 mm. And it's that "a little over" junk that just gets you. I'd personally be happier with a system that went to a decimal foot or something like that. There is a human scale to the Imperial measurements that one can relate to literally by "rule of thumb" that is just coldly missing from the SI metric system.

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