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Discussion Starter · #1 ·
Following along Gary's (roofner) idea I gotta build the MIL a wishing well. Now....... for an octagonal (8 sided) shape using 2 x 4's -- ---- how long should each piece be to make the octagon wheels approx 4' in diameter? This is like horse shoes and hand grenades -- close will work.

There's got to be a formula for this I would think. Or I just go back to the trial and error method. I'd also like to be able to have minimal waste left from the cedar boards -- and what length they should be ie 6 or 8'.
 

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David - Machinist in wood
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I can probably work the math if I think about it for a minute but while I'm thinking about it I can draw it in CorelDraw and give you the measurement - 20", 19.88" to be exact, but I would make them about 20 1/2' to allow for a tiny bit of leeway in cutting your circle.

Text Line Circle Design Pattern


David

Edit - just read your post again and it looks like you want to keep the octagon shape, not round. In that case then 20" would work.
 

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John,

When I was making my turtle planters, I found the best way to get good tights joints in the octagonal body was to make a jig for my miter saw so that all like parts had the identical length. I needed different widths and three different lengths, but the basic jig would be the same. I made a base that bolted to the saw table with a stop at one end so it would be repeatable and then three different stops that were located by dowels to assure repeatability. For a one of project - I've made 8 of these planters to date, and contemplating another run of three - you would just need a simple table with one fixed stop.

Wood Tool accessory Table Plywood Tool


Showing the original (clamped) stop block and the three different lengths of segments required - although each layer is a different width, the inside dimensions are the same so that the cavity where the flower pot goes is the same dimension top to bottom.

Tool Wood Machine Wood shaper Machine tool


Showing one of the removable stops (located by dowels) in place & making the initial cut on the end of the board. Not shown in the photo, but there is a stop underneath the plywood table on the right that locates against the end of the saw table so that the fixture always locates to the same saw kerf.

Wood Table Plywood Workbench Tool


Showing the wood flipped front to back and the cut end placed against the stop, ready to cut to length. To make multiple parts, continue to do this until the board becomes too short. Repeat until you have the required number of pieces. I was starting with 8' lengths, so there is an outboard support for the boards to the right of the saw.

Wood Table Furniture Plywood woodworking


Showing an assembled body, with the five layers glued and screwed together - the body is actually an oval hexagon - the consistent lengths of the parts went a long way to giving me nice tight joints, really struggled with the project until I took the time out to make the fixture. Now, if I damage one of the segments, I can easily set up the fixture and make just one piece that's identical to those made previously.

Good luck.
 

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Theo
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Yeah, I'd wind up with a design like David's. Except I'd just make a circle on 1/4" graph paper, and go from there.
 

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My wheels the long side is 9 inches but width is 3 inches. I would have to measure the short short side of the 3 inch. Then cut the 5 inch block with the short is the same length as 3 inch what ever that new long side is and make all 8 pieces are same length. Think of the segments the 3 wide stock short side are the same on 5 wide you line up it would just be 2 inches wider.
 

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Following along Gary's (roofner) idea I gotta build the MIL a wishing well. Now....... for an octagonal (8 sided) shape using 2 x 4's -- ---- how long should each piece be to make the octagon wheels approx 4' in diameter? This is like horse shoes and hand grenades -- close will work.

There's got to be a formula for this I would think. Or I just go back to the trial and error method. I'd also like to be able to have minimal waste left from the cedar boards -- and what length they should be ie 6 or 8'.
John, where were you during math class? Maybe flirting with the pretty girls. :wink:
 

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Discussion Starter · #8 ·
John, where were you during math class? Maybe flirting with the pretty girls. :wink:
Don,

The older I get, the more I realize I forgot. Who da thunk that I would have needed this 50 years after having to remember it for a test.
 
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Discussion Starter · #10 ·
Most wishing wells use the offset rings not like here you don't want a cone.
Right. I got the general idea on what I want to do now. Doing it is another thing.

How do you secure the side posts to keep them upright outside?
 

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I'd still do it the old fashioned way. Each segment forms an isoceles triangle with the center point. By bisecting the base line you can turn one of the isoceles triangles into 2 right angle triangles which allows you to do the trig functions. Then you either set the newly created side at 24" or set the hypotenuse for 24" (whichever one you want to be 24"). The angle formed from the center point- corner where the hypotenuse meets the base line - and the base line is 22.5*. Once you have a value for the base of the right triangle you double the value for the base line and you have your segment length. A length and one angle is enough to find the other values for the right triangle. The calculator in your computer in scientific mode will make the calculations for you. I could draw out a diagram with formulas if you want (after I reteach myself which I have to do every time I need to do this) -or- you can just keep asking here when you need an answer.
 

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Theo
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Good Lord. I graduated from school in 1958. No way could I remember all those math words, let alone the math formulas. Stuff like that, give me some 1/4" graph paper, a pencil, and a ruler, and I will eventually come up with the answer. And it will work. And that is pretty much how I am designing one of my projects. Oops, forgot the most important element - a good eraser. I think I'll design a nice sign for my shop, saying "Luddite Sanctuary".
 

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Correction: the angle at the center is the 22.5* angle. The angle at the outside is 67.5. Like I said I have to relearn it every time I do it. But it's like riding a bicycle. But then again again I haven't tried riding a bicycle in quite a while. That might not be a good analogy.
 
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Discussion Starter · #14 ·
I kind of liked the idea of asking here. There's most always someone who has the answer on the tip of their tongues and excels at this nerdy stuff - just waiting for someone to ask the question.

I can live with the 20 inches or so. Just got to make them all the same. Ordered the Miterset jig thingie.
 

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Ah, the vicissitudes of reaching a ripe old age. I'm a graph paper and dime store compass kind of guy. Close enough for me. Put the point at a grid line intersection. Oh yes, add a ruler and protractor to the list. I still remember how to divide 360 by the number of segments desired. It's woodworking, not rocket science. I have a pad of 11x17 graph paper around here, somewhere.
 

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Doug
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There's most always someone who has the answer on the tip of their tongues and excels at this nerdy stuff - just waiting for someone to ask the question.
Hey now...... actually we are just seeking some sort of justification for having to learn this stuff in the first place.>:)
 

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Paul
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My mom had one that a friend made. He just used straight 2x4s except for the top row. The top wood was mitered and wider to the outside, like a sill or lip. It had a shingled roof. Mom loved it and always had flowers spilling out of it.
 

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Discussion Starter · #18 ·
Paul,

I got the pics one of those saved. Real nice one. Was leaning that way at first but then got the bug to "try" the angled way. May just do that in the end. Could get an extra piece out of each 2 x 4. Got to see how expensive cedar is at Menards.

Also looking at making a wooden bucket, but those plans might get scrapped due to time and anguish.
 
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Theo
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Ah, the vicissitudes of reaching a ripe old age. I'm a graph paper and dime store compass kind of guy. Close enough for me. Put the point at a grid line intersection. Oh yes, add a ruler and protractor to the list. I still remember how to divide 360 by the number of segments desired. It's woodworking, not rocket science. I have a pad of 11x17 graph paper around here, somewhere.
Yep. But your compass is a bit fancier than mine. This is what I prefer nowadays, and have a mechanical pencil instead of a wooden pencil. https://www.walmart.com/ip/Westcott-Plastic-Compass-with-Wooden-Pencil/55556549 Don't use a protractor much, but do have one handy. And several rulers. My 1/4" graph pads are around 8" X 11", if I need larger, just Scotch tape however many pages needed; got 3 or 4 pads - used to use those for sketchups, but now save them to lay out final designs. For sketching, before school started WallyWorld had spiral pads of lined paper marked down, way down, I got 12 at 25 cents each.
 

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Theo, I found a great drafting set for about 8 bucks at a pawn shop. If you put the center point at a grid intersection, it's easier to set angles with a nice sized protractor, which I probably bought at WalMart.
 
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