Measuring Tools

[ibnaz5150]

I know how critical measurements are in instrument making. So my burning question is.where does one find a rule to lay out increments of a thousand of an inch???For example how to I measure .765 or.062. I'm sure your aware most of the hardware is measured this way. I know a digital caliper would work but geez they're not cheap. What's your method of converting these measurements to standard measuring rules in 1/64's?

[ibanez_crazy]

Harborfreight.com carries digital calipers for 6 bucks. Not great for fretwork, but I use mine for everything else under 6 inches.

[fryovanni]

I use a dial caliper (not digital dunno if there is a real issue there). They can be picked up for less than $25 and get plenty of use. Good tool to have. I also have slotted rules for marking, but they are only good to the 64th, but when you think about the thickness of a fine lead in a drafting pencil you are only going to get so close.When I am checking soundboard thickness or detail work 1/64" can be pretty wide. Fine line binding I use gets down to the .01" range in layups so an extra 64th could be a full width of binding strip. The difference between .110 and .095" on a soundboard is huge, or the flexabilty difference between sides @.09" vs .075" is very significant.

Peace,Rich

[ibnaz5150]

Thanks for the info brother. I'm still researching with this whole process. Have my body wood,ibanez template, 3 books and ofcourse this forum. I decided to take on the neck as well since very few next to none will make a custom ibanez neck. Only downfall is more tools needed which slows things down...upside is I'll have em forever and most likely use them over and over. I'll just pick away here and there as I go along.

[ibnaz5150]

Thanks for the info Rich! I plan on getting stewmac's scale rule & fret slotting rule.Ofcourse will need a caul, radius blocks,fret tools etc. etc..All that good stuff you can't find at your local hardware store. My problem is I'm spoiled with tools. I hate using or refuse to use garbage tools. The better tool not only last longer but generally does a better job!

I'm also a fan of gadgets and jigs making the job faster.

Cheers

Tom

[JJ Rodriguez]

I'm also interested in getting something to measure for fretting. If you use calipers, do you use fret to fret measurements? Is it possible to fret decently using a regular straight edge ruler, a square and a utility knife to score the board? I would just cough up the money for a fret scale ruler from stewmac but they don't have 26.5 or 27 inch templates.

[davee5]

Two comments, one of which I anticipate will be skewered.

(1) On accuracy of fret placement:

I was working on a ridiculous project in college that required me to cut a fretboard into a couple pieces and reassemble them. Living in Palo Alto I went over to Gryphon Strings to consult with the legendary Frank Ford of Frets.com fame about the accuracy of fret placement. He assured me that for all intents and purposes fret placement could be off by as much as 1/32" and still sound fine to the vast majority of ears, and that an inaccurate placement of 1/64" (0.015") would be almost unnoticeable to anyone. Since I was doing machining work with a +/- 0.005" tolerance I figured I was fine.

While I'm sure there are people out there who claim if their frets aren't aligned by lasers and their tuning done with $3000 rack-mounted units and 50:1 ratio tuning machines, I'm inclined to trust Frank. Though contentious, some people need to accept that variations in string pressure applied by your fingers will have more of an effect than misplacement of a fret by a 1/64 of an inch. So maybe, just maybe, a good steel-rule with 1/64" marks on one side is totally fine for fretboard layout.

(2) On Calipers:

Regarding calipers, digital vs. dial. Digital calipers are really handy for 2 things: converting between metric and english units (mm & in) with the push of a button, and easily checking "relative" distances (setting a zero point arbitrarily, rather than in dial calipers where zero is always the closed position).

Let's say you have a neck you really like the taper of (not the fretboard, the neck for illustrative purposes) but you think it's too thick for your next project. You could take the thickness at the nut, set that dimension as zero, and then take measurements up the neck at various points to quantify exactly how the taper changes. Then you could make the neck next a thinner starting thickness at the nut and use your new, no subtration necessary, dimensions to recreate the feel you like. Maybe a lousy example, but the zero set can be very useful.

Since dials are analog and only in one unit you will also have to do math to convert, but most digital calipers have a button that you can push to see that 1.267" is 32.18 mm.

However digital calipers have their own issues. Excessive dust or almost any amount of liquid on the sliding surface can cause errors in reading. While I don't expect anyone in this forum to be checking tolerance on parts flooded with CNC coolant, it's worth noting. When dial calipers get junk in the gear track it's pretty obvious, whereas when digitals skip a beat it's impossible to detect. Digitals also need batteries, which last forever, but still...

My personal biggest issue with digital calipers is flex and the use of discrete units. With dial calipers you can pretty easily tell when you are between lines, closer to 1.267" than to 1.266", but with digital you only get the number on the display to work with, it's quantum measurement. Likewise all calipers, or any precision measurement devices, can easiliy be used with excessive force which distorts the accuracy of the measurement. With dial calipers I find it much easier to watch the dial to determine when I'm pushing too hard and causing the needle to move because the caliper is flexing, not taking up a gap. With digital much less visual feedback is given so many people get readings that can be off by as much as 0.005" (big is engineering terms).

Lastly a good dial indiciator or dial calipers is a finely-tuned mechanical device, like a fince watch, or maybe a good acoustic guitar. We all know there's something visceral about using a finely crafted and carefully tuned mechanical instrument, and it's a satisfaction I never get using digital calipers. But watching that needle spin and hearing the whir of zero-backlash gears inside that little dial housing is a wonderful thing.

Well that turned into a real essay! Anyhow, my $0.02.

-Dave

Edited October 2, 2006 by davee5

[fryovanni]

I should clarify something. I was commenting on tools in general. When it comes to fret placement don't try going fret to fret (you will most likely wind up way off). My comment regarding marking with a pencil is relative to the inaccuracy that it potentially leads to (especially for fret placement). The method I have been using for fret placement is printed templates on durable media that is tack glued directly to the fretboard blank. The layouts are created in Cad and I draw the fret lines at .024". I actually touch my blade(StewMacs circular saw slotting blade) and roll it across the line to confirm it is aligned (blank is locked in my guide to ensure perpendicular slots). There is margin for err in my method (much as any), but it is very very accurate (a quarter blade mis-alignment would be dead obvious and that is .006" less than 1/128th. of course other factors such as paper distortion and so forth are all going to be possible, but it is extreamly accurate). I can not tell what margin of error is acceptable, but do your best to minimise the error. If Frank Ford says 1/64th. well that is probably perfectly acceptable.

I have never owned digital calipers, but am going to try them out. I still have my dial (and I really like it), but digital seems to have some nice features. I do wonder some times when I will go overboard with the tightness of tolerances (we work with wood not metals). It is so satifying to see a super clean joint line(even if I am probably the only one that notices).

Peace,Rich