How to Draw an Octagon
In this video, Ben Strano demonstrates two methods for laying out an octagon without a protractor
It seems like the more woodworking I do, the more I notice octagons used in woodworking projects. Not only is this shape the basis of an attractive form–not a square, not a circle–it is the basis of a lot of techniques, used especially when making chairs. In Fine Woodworking #278, Elia Bizzari built an eye-catching octagonal table, and demonstrated a way of laying out octagons that I had never seen before. According to deputy editor Jon Binzen, Elia used this layout method because his stock wasn’t square. One of the downfalls of my tried-and-true method was that you must start with square stock. Elia’s method is one I’m happy to add to my bag of tricks! I included both methods in this post so you can add both to your own bag.
1) Using a compass, draw a circle equal to the the intended width of the octagon.
2) Use a square to draw a square that is tangent with the circle.
3) With a straightedge, draw diagonals that bisect the square.
4) Place the square along the diagonal and draw a line along the other leg.
5) Flip the square to finish the line.
6) Your octagon is laid out!
I learned this method during a class I took with chairmakers Jeff Lefkowitz and David Douyard. We used this technique to lay out octagons on the leg blanks of our ladderback chairs. Unlike the method above, this method requires that you start with a square blank.
1) Draw a line connecting the diagonals. You really only need one. Here I did two more out of habit than anything.
2) Measure from the corner to the center intersection
3) Using that measurement, mark lines from each edge
4) Connect those lines and you have laid out the corners of the octagon
5) Rinse and repeat
Interesting. I had not seen the second one. Very fetching ukulele sounds. Sweet sounding instrument. Next time, do "Hawaii Aloha", brah.
Nicely done Ben.
For what it's worth, I'm a designer and have done a LOT of pencil drawings using triangles, squares, and rulers. One trick I learned many years ago as a student was to rotate the pencil as you draw a line. It's very easy to do once you give it a try, just slowly rotate the pencil between your fingers while you draw the line. It keeps the pencil point sharper because it removes the lead equally from around the point as you draw which also keeps your line weight way more consistent. After a while it becomes second nature to draw while rotating.
You can do this (on square stock) without any measurements or marks. Set your TS blade to 45 degrees and lay the stock on the blade (with a corner edge on the table). Bring your fence to the outside corner edge. Now when you lay your stock flat on the table it will be set up to cut an octagon.
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