Geometry / Math Wizzes ... Help needed.

[Fishbucket]

I have seven 2x4s 17" long. I'm going to make a heptagon column that an 8" circle would be covered by wood. ( so I can run it on the lathe and turn it down to 7 3/4" )

What's the angle and inside corner to corner measurement ?

Is there a free web page to do this calculation ?

 

[Michael Mathews]

360 / 7 = 51.4285 deg.,
divide that by 2 = 25.714 deg. is the angle that you need to cut on each side of your 2x to mate them all for a 7 sided shape!

 

[Dave Richards]

I'm not exactly sure what you are after. How does the 17 in. come into it?

The angles are as below...

 

[Michael Mathews]

Dave, I believe he's making a 17" tall column. at least that's what I assumed

 

[Fishbucket]

I'm not exactly sure what you are after. How does the 17 in. come into it?

The angles are as below...

The 2x4's are 17" long .

 

[Fishbucket]

Dave, I believe he's making a 17" tall column. at least that's what I assumed

Correct

 

[Dave Richards]

OK. So to get one that has a 7-3/4 in. diameter, you'll need staves that are about 3-55/64 wide. That gives you 8 inches across before turning.

 

[Dave Richards]

FWIW, if your stock is 2x4 stock that is 3-1/2 in. wide, you'll be hard pressed to get a 7-3/4 in. dia. column out of it.

 

[Fishbucket]

Wow Dave !
Thank you.
What wood be the diameter with using 2x4 ?
I could rip down some 2x6 to 3 55/64 " if needed.

 

[Dave Richards]

You could get a 7 in. dia. column with 3-1/2 in. wide staves. Maybe slightly larger.

 

[JohnnyR]

Might be easier to add another 2x4 so you have more lumber to slice away if your gluing or turning skills aren't any better than mine.

 

[Charlie]

Might be easier to add another 2x4 so you have more lumber to slice away if your gluing or turning skills aren't any better than mine.

Yes, then you will be working with 22.5 degrees instead of 25.71428571. Lol.

 

[Fishbucket]

Might be easier to add another 2x4 so you have more lumber to slice away if your gluing or turning skills aren't any better than mine.

Perhaps that’s a better Idea...

Thanks

 

[Dreuxgrad]

Refer to this: Woodwork Segmented Turning Calculator with Full Scale Printable Templates - Inch

 

[Fishbucket]

Refer to this: Woodwork Segmented Turning Calculator with Full Scale Printable Templates - Inch

There we GO !
Thank you !

 

[Michael Mathews]

Refer to this: Woodwork Segmented Turning Calculator with Full Scale Printable Templates - Inch

Thanks Ed! I was unaware of this website!

 

[WoodWorksbyTim]

Refer to this: Woodwork Segmented Turning Calculator with Full Scale Printable Templates - Inch

Wow...great find. Thanks for posting!