Roof Cupola

reible · Post by **reible** » Wed Sep 26, 2007 12:15 am

Hi Ed,

Yes it does get a lot more confusing when the parts start meeting at angles. What you have is intersecting planes and since you want the joints to fit this means that the angle become compound and you need trig functions to figure then out. Or a program like Dusty found or a nice table to read the results off of.

Here is a page that has some idea of how this might be done:
http://www.betterwoodworking.com/compound_miter.htm

Keep in mind this table is going to have the slope done differently then I did mine so what I have at 0 they have at 90.... if you can follow that.

This is not the same way I did it but the general idea is the same. Hope that gets the belt back on the pulley for ya.

Ed

dusty · Post by **dusty** » Wed Sep 26, 2007 7:49 am

Thanks for the brain teaser, Ed.

Glad I didn't wake up and do this one in the middle of the "knight". I like your first chart best.

Ed in Tampa · Post by **Ed in Tampa** » Wed Sep 26, 2007 9:41 am

reible wrote:Hi Ed,

Yes it does get a lot more confusing when the parts start meeting at angles. What you have is intersecting planes and since you want the joints to fit this means that the angle become compound and you need trig functions to figure then out. Or a program like Dusty found or a nice table to read the results off of.

Here is a page that has some idea of how this might be done:
http://www.betterwoodworking.com/compound_miter.htm

Keep in mind this table is going to have the slope done differently then I did mine so what I have at 0 they have at 90.... if you can follow that.

This is not the same way I did it but the general idea is the same. Hope that gets the belt back on the pulley for ya.

Ed

Ed
Thanks for the referrence! That brings back some old memories.
I understand the basis of math however I thought there was an easier way.
Also I think this can be done on a framing square.
I need to play around a little bit and see if I can't jog those old memories lose.
Tampa Ed

dusty · Post by **dusty** » Wed Sep 26, 2007 10:18 am

The two charts that you provided, ed, can be a bit confusing. It all comes clear (clear as mud) when one accepts the fact that 0 degrees on the miter gauge is really 90 degrees.

Can anyone explain why this convention developed. Why is a 90 degree cut on the table saw indicated on the miter gauge as 0 degrees?

Yes, this just might all be hidden in the numbers on your framing square. I have a manual (somewhere) that explains how to use your framing square. I'll go on a search.