Roof Cupola

dusty · Post by **dusty** » Mon Sep 24, 2007 7:36 am

Here is a site that provides access to several programs for making calculations that may be useful in your shop. Enjoy.

http://www.woodcentral.com/bparticles/b ... #downloads

I prefer "Polygon Angle Program" for the question asked in this thread.

Ed in Tampa · Post by **Ed in Tampa** » Mon Sep 24, 2007 11:08 am

reible wrote:Maybe you do maybe you don't.

If you are talking about the upright structure, a 10 sided box then you have the right answer.

If you want to make the roof then sorry to be the one with the bad news but you do not have the right answer yet. Unless you make a flat roof.... my guess is you will have some sort of slope to deal with and then you have a compound cut and the answer you have will not work.

If this is the case then I'll let you guys work on this for a while and if you can't figure it out I'll be back..... you will have to provide a slope to work with however.

Ed

Ed your right I was only talking the bevels cut make a straight walled structure. The roof is a whole another story and since I "don't do roofs" I will shake my head and nod. Seriously I have a hard enough time figuring out one plane roofs I can't imagine where to start.
I suspect you combine the 18 degrees with the degrees of roof pitch in some form or fashion but I have no idea of the fashion.
It is like crown molding when I need to cut it I set the mitre saw to the spot marked for crown molding and cut.

I do know you can cut crown molding by holding the molding at the exact angle it is going to be installed and cutting a forty five on the end. I suspect you could do the same thing here. Decide on the slope you want and then set the roof panel in that slope and cut panel at 18 degrees. I think that would work without any calculations.
The other Ed

reible · Post by **reible** » Mon Sep 24, 2007 12:43 pm

I've never tried to attach a pdf so if this works you should have a document with 3 tables with 3 to 20 sides and slopes from 0 to 90.

I'll have to see if my math and what Dusty posted are close to being the same.

I'll spare you the math involved... you can all thank me later for that.

Ed

dusty · Post by **dusty** » Mon Sep 24, 2007 1:39 pm

I'm dying of curiousity and I can't read your .pdf.

I'm not sure why.

Just to satisfy my curiousity, if we were talking about a roof on a building with 10 sides and a pitch of 20 degrees - would the answers be table tilt of 17 degrees and a miter gauge setting of 83.75 degrees (6.25 degrees cut)?

reible · Post by **reible** » Mon Sep 24, 2007 2:01 pm

Gee I'm sorry you're having problems reading the file. I've checked it on my main machine and laptop and they both work fine...???? The file was generated by open office. Since being retired I can't afford the Adobe writer or the MS Office so I have no tools to generate anything else.

Sounds like your numbers are close to what I have 16.9 and 83.7. Rounding errors is my guess.

Ed

charlese · Post by **charlese** » Mon Sep 24, 2007 9:20 pm

Hey Ed! Just wanted to tell you I can read all three pages of your PDF post just fine! Don't quite know what it all means, but will try to figure it out when back at home. I'm sitting in a KOA in Missoula, MT using their free Wi Fi. Works O.K.

Dusty - have you updated to the newest FREE Adobe reader?

Ed in Tampa · Post by **Ed in Tampa** » Tue Sep 25, 2007 10:40 am

reible wrote:Gee I'm sorry you're having problems reading the file. I've checked it on my main machine and laptop and they both work fine...???? The file was generated by open office. Since being retired I can't afford the Adobe writer or the MS Office so I have no tools to generate anything else.

Sounds like your numbers are close to what I have 16.9 and 83.7. Rounding errors is my guess.

Ed

Ed
I have got to ask how did you generate these numbers?
What was the math?
The other Ed

dusty · Post by **dusty** » Tue Sep 25, 2007 10:56 am

charlese and Ed - I have Adobe Reader 8.1.0 loaded. The file downloads but is blank (that is - no data). Got a feeling something went wrong during the initial download. I'll attempt to attach it from a different computer - I put a call out to the Grandkids to bring back Gramp's laptop.

reible · Post by **reible** » Tue Sep 25, 2007 11:38 am

Ed in Tampa wrote:Ed
I have got to ask how did you generate these numbers?
What was the math?
The other Ed

Hi Ed,

What I did was figure out the trig functions then did a spreadsheet so I could just plug in the numbers and generate the tables I posted. I was having trouble sleeping the other night so I "figured" a little math might help me sleep, and it did, or was it because it was 5 in the morning??

Now I'm waiting for someone to notice that they are going to have to know just how wide each piece is. I've already had to do that for a guy who was building a drum and for a couple planters I made. I guess turners who do segmented bowls have to do that all the time??

Ed

Ed in Tampa · Post by **Ed in Tampa** » Tue Sep 25, 2007 12:32 pm

reible wrote:Hi Ed,

What I did was figure out the trig functions then did a spreadsheet so I could just plug in the numbers and generate the tables I posted. I was having trouble sleeping the other night so I "figured" a little math might help me sleep, and it did, or was it because it was 5 in the morning??

Now I'm waiting for someone to notice that they are going to have to know just how wide each piece is. I've already had to do that for a guy who was building a drum and for a couple planters I made. I guess turners who do segmented bowls have to do that all the time??

Ed

Ed
In an effort to make two Ed's better than one I still can't figure the basis.
For example to figure straight sides you only need to divide the number of sides into 360 degrees for an enclosed box and then divide that number by 2 since the bevel is divided between two edges.
But what is the premise for figuring bevel and tilt? I know I knew this once but for the life of me I can't remember it now.
The Tampa Ed