Is there a jig for sawing hexagons?
JohnH
| Posted in Jigs, Fixtures, Tips & Tricks on
I want to make about 150 small hexagons of about one inch across, but not all the same size. Is there a jig to make this easy?
I can figure out how to make opposite sides parallel and getting the first 60 degree angle. But getting the second 60 degree angle cut such that the two edges are EXACTLY the same length is not so obvious. I would like to avoid measuring each and every hexagon.
Thanks in advance.
Replies
That sounds like a challenging project, John. With the info you provided, I have this thought, guessing that you want face grain on the face. Could you stack a bunch of pieces like pancakes? Mill them in to a long square stick and then make a sled. If you held the piece in the sled with pins on the center of the ends, like a lathe, you could turn the work and leave the saw at 90°. If the pieces are all different, as in graduated, you could set the work so that it will taper on the sled. Then slice up to the thickness you needed. It sounds easy on paper but you will want to make some extras, I'm sure.
Beat it to fit / Paint it to match
There are a couple of approaches, but it would help to know how thick the hexagons are, the type of wood, and the grain orientation.
John W.
Edited 2/1/2007 12:06 pm ET by JohnWW
Hello JohnWW,
The hexagon pieces are intended to make a hemispherical dome. They are 1/4" thick with the faces being face grain. For a decorative effect, I planned to have the grain direction rotate between adjacent hexagons. I know the edges need to be angled to accommodate the curved shape. The hexagons will be glued together inside a dome form (kitchen collander). In a trial run, I found that the hexagons need to get smaller as they progress from the top/center to the edge/rim. This is the well-known problem of representing the globe of the earth on a flat map.
I would appreciate any advice or suggestions you may have.
My understanding of your description is that you want to tile the surface of a sphere. I think you may need a combination of hexagons and pentagons to do that. Then you also only need one size of each.
Hello Ben,
Can you give me more information on how hexagons and pentagons combine to produce a hemisphere?
Thanks, John
John-A Google search on "geodesic dome" turns up a number of sources. The Wikipedia entryhttp://en.wikipedia.org/wiki/Geodesic_domehas illustrations showing a dome composed of a mixture of hexagons and pentagons and one consisting entirely of triangles.
As Ed alluded to in Message 12 a soccer ball is made up of hexagons and pentagons. I don't believe it is possible to make a sphere out of just hexagons. Obviously, a side of the hexagon has to be equal to a side of the pentagon. You will need to do some research on the actual length if you want a sphere of a particular diameter. Post photos of your project; it sounds interesting.
John,
Make a jig to do this by cutting a larger hexagon out of mdf or good plywood . Size isn't that important, something around 6" across the flats would seem about right. Place a small knob in the middle of one side to make it easier to handle.
Now take a slightly oversize blank piece of stock, and attach it to the center of the hexagon with double sided tape.
Set up your table saw with the rip fence about 3 1/2 inches away from the blade, for a 6" across hex jig, and the blade height just a touch higher than the stock thickness. Now just pass the hex jig over the blade, with the side holding the blank against the table and one side of the hex running along the fence. Continue taking cuts, making one pass along each of the six sides of the jig. When you've taken a pass on all six sides, the blank will have been cut into a hex also.
You may want to tape a few scraps of the blank trims to the perimeter of the jig, out of the path of the saw cuts, so the jig will ride steadily on the table. By moving the fence you can change the size of the hexes and you can bevel their edges by tilting the blade.
Use heavy duty carpet tape for attaching the blanks. You should be able to do several blanks before the tape starts to lose its grip and will need replacing.
I would agree with another poster that you probably can't do the tiling with just hexes. You should be able to track down the hex and pentagon approach by researching Buckminster Fuller (or take a look at a soccer ball). Fuller actually designed a map that kept the continents in fairly good proportion by tiling a globe with his dome segments and then unfolding them to lay flat.
John White, Shop Manager, Fine Woodworking Magazine
Edited 2/1/2007 6:41 pm ET by JohnWW
Hello JohnWW,
Thank you for your very clear description of a hexagon-cutting jig. In some ways it is like a pantograph without the arms. Any-who, it is clear and will do the job quite well.
Best regards, JohnH
Woodwork magazine #54 has an article on making a wooden soccer ball. The approach involves using steel patterns to make the individual pieces. There's also some discussion about gluing the thing together which might be useful to you.
Ed
Hello Ed,
Is that issue available on the internet?
Thanks for the tip.
John
Not to my knowledge but you can buy it:
http://www.woodwork-mag.com/back_issues.html
Ed
I think the old router lathe, which has indexing facility, would enable you to machine end grain bars. Trend sold it here but did it start as Porter cable?
You are right, they must be unequal size, as there are only 5 regular convex polyhedra: http://en.wikipedia.org/wiki/Platonic_solid
fwiw I wandered around in Wikipedia and discovered that the soccer ball form is called a Truncated Icosahedron.
http://en.wikipedia.org/wiki/Truncated_Icosahedron
Ed
Many thanks to all. You kept me from going down the wrong path (all hexagons of varying size) and steered me to the correct approach (both geometrically and simpler construction). It will take me a while to complete the project, but I will post it in Knots forums.
Best regards, John
I don't know if it's of any use, but Jim Cummins' video on small shop projects has the procedure for cutting hexagons. One of the boxes he made on this video was a icosohedron. (Jim, besides being a great guy, was one of the early editors of FWW and co-founder of WoodCentral).
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