topic Re: Hip angle formula in Libraries & objects

Hip angle formula

Aussie John — Tue, 27 Feb 2007 01:36:44 GMT

heres a q for the maths gurus.

for any given roof of pitch "roof_ang" what is the formula for calculating the angle of an element placed oblique the fall line of the roof ("obj_ang")

eg at the hip - "obj_ang" would be 45. (if roof pitches are equal)

thanks

Re: Hip angle formula

Rod Jurich — Tue, 27 Feb 2007 02:19:10 GMT

Aussie wrote:
/....
for any given roof of pitch "roof_ang" what is the formula for calculating the angle of an element placed oblique the fall line of the roof ("obj_ang")

eg at the hip - "obj_ang" would be 45. (if roof pitches are equal)

I'm no guru, John, but is this what you want?
If so the maths is in the part here.

Re: Hip angle formula

Aussie John — Tue, 27 Feb 2007 07:39:11 GMT

Rod wrote:
I'm no guru, John, but is this what you want?
If so the maths is in the part here.

Rod- Ill have a closer look at your library part. What i am hoping to do is be able to place a capping as a roof accessory and by varying the 2d angle in plan get an automatic correction the the inclined angle.

Re: Hip angle formula

Anonymous — Wed, 28 Feb 2007 17:31:01 GMT

Aussie wrote:
heres a q for the maths gurus.

for any given roof of pitch "roof_ang" what is the formula for calculating the angle of an element placed oblique the fall line of the roof ("obj_ang")

eg at the hip - "obj_ang" would be 45. (if roof pitches are equal)

thanks

I don't know if it helps but I find it much quicker to cut a section through and measure the angle rather than getting into maths. Let the computer do the maths - that's what it's for!

If you need the formula for scripting an object for instance then I'm sorry - this advice is useless!

Re: Hip angle formula

Aussie John — Wed, 28 Feb 2007 21:51:38 GMT

I think I have worked it out.
angle of hip =ATN(tan(AC_pitch)*cos(angleofobject))
for a normal hip angleofobject is 45
and AC_pitch is the angle of roof to which the accessory is applied

Re: Hip angle formula

gpowless — Thu, 01 Mar 2007 12:27:37 GMT

In terms of carpentry, the hip slope is always (pitch)/18 when the main pitch is expressed in (pitch)/12.

Re: Hip angle formula

Anonymous — Thu, 01 Mar 2007 15:53:08 GMT

gpowless wrote:
In terms of carpentry, the hip slope is always (pitch)/18 when the main pitch is expressed in (pitch)/12.

Thats not correct, its 17 not 18. For example, a 4"/12" roof pitch has a 4"/17" hip/valley pitch.

But here is a good cheater calculator. http://www.ls.net/~windyhill/Calcs/hipbackangle3.htm

Jim