Woodworking Basics — How to Use a Sector
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- This topic has 8 replies, 6 voices, and was last updated 11 years, 1 month ago by Ken.
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8 March 2013 at 10:46 pm #9036
Thanks Ken for the video, I have seen this demonstrated by Chris S. before. He actually is pretty much a Hand Tool junkie if you will and I find him interesting, I do like his style. He is an entertainer to make things interesting. I like his writing style as well and if you have not read his books I think you would enjoy them. I am glad he still contributes to Polar Woodworking which is one of my favorite Mags.
Steve
9 March 2013 at 12:34 am #9043Interesting, never seen one of those. Not something I plan to make but I’m sure it’d be useful for a lot of things.
There was a discussion thread about sectors a while back on a forum (cannot remember which one), and although the verbal explanation eluded my grasp at the time, there was mention that some old folding rules have lines that radiate out from the center pivot (hinge), allowing them to be used as sectors.
Here is another video by Chris S. showing how he converts a crappy 4-fold folding rule into smaller sector. Same idea as the big boy.
http://www.popularwoodworking.com/article/make-a-sector-from-a-crappy-folding-rule
It must be catching on again. They are now selling these
The scale of chords and circumferences is a modern descendant of the sector rule and is used in conjunction with a pair of dividers.The main use of the scale of chords is to convert a numeric angle into a physical one and vice-versa. The hinged rule is set by spanning the desired numeric angle on the scale of chords and then laying the points of the dividers into two punch marks on the rule. To measure a physical angle you simply use the same process in reverse.
On the back of the rule is a scale of circumferences, which in conjunction with the standard metric scale, quickly transposes the diameter of a circle to give its circumference. Very useful when calculating material requirements for projects.
Standard at 20 degrees C
Stainless Steel
Etched Markings
Made in England
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