star layout

Google knows: *LINK*

Don Thompson - Cutler Ridge, Florida

>Basically, you start with a pentagon. Here are the details:


How to Draw a 5-Pointed Star

Re: star layout

Don Thompson - Cutler Ridge, Florida

>Here is another one.

That fits the bill

Jack Guzman from Maine

>Don,that looks like it will do the job just fine.

I'm making a crib for my niece. The headboard is going to have a sun in the center flanked by a star and a crescent moon. My niece gave me a rough sketch of the design and I'm going to scroll the designs in.I drew the moon by making an arc with a compass and moving the point over for the inner arc. For the sun I'll compass a circle and freehand the rays. thanks---Jack

Re: That fits the bill

Alan Hamilton

>Jack,

The easiest way I've found is to use a divider. Scribe a circle, and without changing the setting of the divider, pace around the circumference. It's not perfect: the radius of the circle (the setting of the divider) goes almost exactly five times around the circumference, but will be just a tad short--and I mean just a tad. Even without refining it further, this makes a five-point star so that the very little it's off isn't really noticeable.

When I need to be more exact, I either scribe the circle and then open the divider setting a teensy-tiny-itsy-bitsy bit, and do a little trial and error; or I begin on the top star point, then go two steps in one direction from the top point, and then two steps in the other direction from the top point. The latter is the much easier way, though not as exact; it makes the bottom two points slightly farther apart than the others, but they're really unnoticeably farther apart.

Alan

Re: That fits the bill

Jack Guzman from Maine

>I never thought of that.I'm new to a divider. First time I ever used one was to lay out dovetails following Rob Cosman's video.

Using a protractor works but it is a little involved.This way looks simpler.I'll try it. Thanks---Jack

Re: That fits the bill

Don Thompson - Cutler Ridge, Florida

>Thinking about it, it is a lot like the Cosman dovetail layout method. Just adjust the dividers up or down to get a whole number of segments, which in this case, must be five. Cool.

Re: star layout

Nicholas Carey

>You can always use the old-fashioned draughtsman's construction:

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Construction Of a Regular Pentagon or Pentagram In a Given Circumscribed Circle

The figure below shows a method of constructing a regular pentagon/pentagram in a given circumscribed circle using nothing but straight-edge and a compass.

To construct the regular pentagon/pentagram:

1. Using a compass, draw the desired circle that will circumscribe the pentagon/pentagram.



2. Draw a horizontal diameter AB and vertical diameter CD.



3. Locate E, the midpoint of radius OB.



4. Set a compass to the spread between E and C, and, with E as the center, strike arc CF.



5. Set a compass to the spread between C and F, and, with C as the center, strike arc GF.



6. A line segement from G to C forms one side of the pentagon.



7. Set a compass to GC and lay off this interval from C around the circle.



8. Connect the points of intersection.

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Note that the formal constructions of regular polygons (a geometric construction is a way of laying out geometric forms with only a straight-edge and compass as tools) and other geometric forms were first laid down by Euclid in his The Thirteen Books of the Elements, written some 2300 years ago.

Euclid's constructions include, among others, pentagons and hexagons.

The Euclidean construction to inscribe a regular pentagon within a circle is laid down in Book 4, Proposition 11. The construction to circumscribe a regular pentagon about a given circle is laid down in Book 4, Proposition 12.