Judging from the responses to a previous post about Crucible-brand dividers, I believe a post about how to use dividers and compass would be beneficial.
let's begin the discussion with a basic technique. I encourage others to add their techniques to this thread. I will try to add more later.
I learned how to use dividers/compass for carpentry and woodworking as a boy from my father, and from carpenters and other craftsman on jobsites over the years. But I learned the most from drafting classes in college. This was before drafting heads, digital protractors, dot-matrix printers, and CAD. Even lettering was done by hand or using plastic/metal templates. The professors were justifiably proud of their hard-earned skills and the beautiful and precise documents they could deftly produce.
The first lesson we were taught was this: Never lay the tape or rule or scale on the drawing/workpiece and mark directly using pencil or pen, but instead use dividers to first measure the required distance on the scale/ruler, indexing the divider's points in the engraved lines, and then use those same dividers to transfer and mark the distance onto the workpiece or paper.
The intuitive, but inefficient, way most careful people do the job is lay the ruler or yardstick or tape measure on the workpiece, index one end (a careful man will always "burn" 1" or 12" and not index directly on the tool's end), locate the target distance on the measuring tool, and make a mark. But if he is trying to layout an irregular distance like 2-3/64" (= 52 (51.99) mm), for instance, a pencil's lead or pen's tip is too wide for precision, so he will use a scribe or marking knife. To be more precise, a careful man will tip the scale or ruler on its edge, kneel down so he can see the scale's/ruler's marks clearly, fit the scribe point or knife tip into the engraved line on scale/ruler, and then transfer that to the workpiece, paper, or story stick with a quick "tick." The problem is that the far end of the ruler/scale at the point he is measuring from may wiggle out of alignment messing up his precision. Or the scribe/knife point may shift while making the "tick." With practice, these tendencies can be overcome, but clearly this method is time consuming and the results may be questionable.
But if he uses dividers, he can fit/index their points quickly and precisely into the engraved lines in scale/ruler at each end of the measurement, first time everytime, and without kneeling or squinting or pressing down, or worrying about wiggling and shifting. Once he has set the dividers to the required distance, he can fit one of the sharp points precisely into the index hole, or onto the line he is measuring from, and then use the other point to make a precise scratch or hole in the workpiece, which can be used again for future layout reference.
This works with dividers or trammel heads.
Standard dividers are quickest, but a locking divider with screw adjustment is easier to adjust precisely and is more likely to retain the measured distance with repeated usage. You will find when drafting or doing layout that you repeat some distances frequently. Having 2 or 3 locking dividers set to these distances close at hand will allow you to layout those distances quickly and accurately without the need to refer to scale/ruler.
The quality of your scale/ruler becomes important when attempting precision layout. A high-quality, professional-grade scale or ruler must of course be of proper length and uniform width and thickness, be free of twist, and have accurate lines. Be careful to procure one that will pass these 3 simple quality tests, not an easy task nowadays. Pay attention that the ruler/scale you use has engraved lines of uniform depth and width to properly index divider and scribe points, and marking knife tips.
These principles apply to story sticks as well.
Give it a try.
Stan
PS: We should also create similar threads that deal with other ancient and venerable tools such as the square, plumb bob, and various versions thereof.
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Originally Posted by Pat Barry
