Replies

1. 
   Joseph_Fusco | Dec 08, 2001 11:09pm | #1

   *

   Boyd,

   • Step One

     Divide larger pitch by smaller pitch and multiply 12 by that quotient.

     14.625 / 10 = 1.4625

     12 * 1.4625 = 17.55

   • Step Two

     sqrt(17.55²+ 144) = 21.26

   • Step Three Hip/Valley Angle

     Inv Tan (14.625 / 21.26) = 34.52°

   For drop amounts and back bevels you can read it.

   View Image

   "The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it."

   Aristotle

1. 
   boyd_miller | Dec 09, 2001 06:26am | #2

   *Thanks Joseph for the shortcut to getting the irregular hip/valley pitch even if the 3d sense of it doesn't possess me. Getting the backing bevels remains a stretch i see .Your great graphics display the 3d way that does make sense to me and thus do the math step by step. I suspect though i'll be cutting pitch block helpers till my balance goes and they have to let me trim.

1. 
   Joseph_Fusco | Dec 09, 2001 07:06am | #3

   *boyd,

   Sometimes it's best to have no sense at all. . . That's why I try and spend most of my time senseless ;-).When I was reading your description on how you use your square to find the hip pitch angle;

   "i drew a 10-14.625 rectangle with a diagonal line corner to corner, squared to where 12" intersected the diagonal line coming off the 10/12 side, measured the length of that point on the diagonal to get the pitch of the hip ( 10/ 14.56 i think it was)"

   I'm a bit fuzzy on this. Do you think you can explain it a bit further? I only ask because I think you getting the wrong hip angle. Also, I have a super way to use my square to figure all this stuff out.

   View Image"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle

1. 
   boyd_miller | Dec 10, 2001 06:15am | #4

   *Joseph, if i had your computer skills i'd draw it out and post it but i think i can reword it.It 's so simple i had a curious mason nodding comprehension.5 or so years ago Carl Hangstrom and Don Zepp explained it in an article in JLC calling it the Zepp method .I learned it in the process of drawing things out , over complicating it to begin with and finally simplifying it with input from a past employer who when i went to work with did his math on a scientific calculator watch. On an irregular pitch roof(90' corner) it was an illumination to me that the angle the hip made was the angle of a diagonal drawn across a rectangle with the sides matching the two rise pitches.I would figure from the 12" unit run rise of the main span and figure from that to get the run of the opposing pitch.Anyway using the two pitches in the roof i started this post with i would draw a rectangle with 10" and 14 5/8" as sides, then draw a diagonal between them, then slide a square along the 10" side of the rectangle till 12" intersected the diagonal, mark it and then measure the distance the mark was along the diagonal from the corner of the side 12" was squared from.The measurement was 14 9/16" (14.53 was the math). So knowing 10" was the rise at the 12" squared mark , 10" and 14 9/16" is the rise and run of the hip.Its a doubled hip in this instance and with a short piece of rafter material with the level cut of the hip pitch placed to each side of the diagonal line and the inside of the blocks exactly on the corner, mark the outside of the blocks where the sides of the rectangle cross then square down from the pitch plane to use with the rafter thickness to get the backing bevels.I inv tan these legs and the plan view angles because i find it easier, faster and more accurate then using a speed square as a protractor. With single hips on an irregular hip i drop them . Joseph- is the above method what you do with a square?It's old as squares i bet. The graphics of geometric projection in some old carpentry books i have says alot about the level of skill back then with some of them anyway. I still feel like a fake carpenter after 27 years.

1. 
   Joseph_Fusco | Dec 10, 2001 03:56pm | #5

   *boyd,

   Thanks for the better description, I can see that you are getting the right hip run and angle.The only question I have is that in your description you say;

   " i would draw a rectangle with 10" and 14 5/8" as sides, then draw a diagonal between them, then slide a square along the 10" side of the rectangle till 12" intersected the diagonal, mark it and then measure the distance the mark was along the diagonal from the corner of the side 12" was squared from."

   It seems to me that you would need to slide the body of the square along 14-5/8" side and when the 12" mark on the tongue intersected the diagonal line mark it there. If you did the same on the 10" side the 12" mark on the tongue of the square would fall outside the rectangle. This is not bad, but you'd need to extend the diagonal line to intersect the 12" mark on the tongue. That measure would make the diagonal line 21-1/4" and it would be the run were the rise would be 14-5/8". If you do and Inv tan on these two numbers you get the same hip angle as you would for 10" and 14-17/32" which is 34.52°Hopefully I've understood you this time.

   View Image"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle

2. 
   boyd_miller | Dec 11, 2001 04:05am | #6

   *Joseph, i get it, dyslexia does suck. You are pulling my leg aren't you?Actually i was hoping someone would call me on dropping the irregular hip.

3. 
   Joseph_Fusco | Dec 11, 2001 06:22am | #7

   *boyd,

   I think we just have two different methods for doing this, each producing a correct answer. This graphic may help.You can apply the math on this page to confirm the graphic.

   View Image© 1999-2001"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle

4. 
   boyd_miller | Dec 12, 2001 04:36am | #8

   *Joseph, how do i do the graphic stuff you do? is it part of windows 98 somewhere? If i could of done a graphic, things would have been clear to begin with . Sorry . Anyway i realized what you did with the square and realized what you thought i did.After reading your last post i see i didn't make myself understood .With the tounge on the 10" side i squared to where 12" intersected the diagonal on the blade.I actually just measured with a tape eyeballing square. I see you thought i lined up 12" with the corner instead of 12" on the diagonal.Without a 12" leg though i'd extend it like you show.I really did think when i posted last you were pulling my leg squaring from the 14 5/8 side to get 12 out to the diagonal knowing 12 was an airball. But then i'm often laughing at jokes people aren't making.It's sort of a tag trait to paranoia.Thanks again for the condensed trig formula.

5. 
   Joseph_Fusco | Dec 12, 2001 06:27am | #9

   *boyd,

   If you don't have a "drawing" program in will be hard for you to produce graphics. You can use "PAINT" which is a simple drawing program that can be found if you go to "START>Programs>Accessories>Paint" You can put some simple drawings together with it.I'm still wondering if you have a method to calculate the Hip drops using the square? If you don't I'd be glad to give you one. As a matter of fact you can calculate all the information for irregular pitch roofs just using a square. It should take no more then 2 mins and no need for batteries.

   View Image© 1999-2001"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle

6. 
   boyd_miller | Dec 13, 2001 06:35am | #10

   *Thanks Joseph, i use a pitch block of the hip and mark it on the rectangle but i can see doing the same thing graphicly using the square and the rectangle for reference measurments.Drop or bevel.I'm amused by practical solutions and enjoy learning new ones.Dropping a single member irregular hip........got a go , alarm goes off at 10 after 4.

7. 
   Joseph_Fusco | Dec 13, 2001 06:45am | #11

   *boyd,

   I at least get to sleep till 5 AM. ;-}

   View Image"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle

8. 
   jacksprat_ | Dec 13, 2001 02:33pm | #12

   *Thank god. I believe that Gross did get the drop/bevel angle wrong.He made me feel a little dumb.

9. 
   Joseph_Fusco | Dec 13, 2001 04:43pm | #13

   *boyd,

   Is this something similar to the method you use?

   View Image"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle

10. 
    boyd_miller | Dec 14, 2001 06:29am | #14

    *Joseph, one of the expanded views came up as a black box.None the less it is " something" similar but goes a step past my dumb intuition.I hadn't recognized that the distance towards the 90' corner squared over to the diagonal was the run to get the drop .Cutting a pitch block and placing it along side the diagonal line as it would actually be placed unbacked and marking it would be easier for the carpenters i work with to "get" i think. Since you haven't accosted me regarding dropping single member irregular hips and since ......dang look what time it is, got to go.Thanks for the insight.

2. 
   boyd_miller | Dec 14, 2001 06:29am | #15

   *
   On irregular hips the number of steps i have to take trig wise to get the hip pitch and backing bevels is so lengthy that for practical purposes i find it easier to do it graphically(or look in roof framers Bible). For example today on a snub hip off a gable wall with a 14.625/12 10/12 combo (not in the Roof Framers Bible) i drew a 10-14.625 rectangle with a diagonal line corner to corner, squared to where 12" intersected the diagonal line coming off the 10/12 side, measured the length of that point on the diagonal to get the pitch of the hip ( 10/ 14.56 i think it was) , cut the level cut of it on a block, placed it to each side of the diagonal , marked each side where the the outside of the rectangle line crossed, squared down(not up) from the pitch block and divide that measurement into 1 1/2" ,inv tan it for the backing angles, inv tan the 14.625 10 legs for the plumb bevel and compliment and finally tape the hip length.This might seem long but ( time flies when your having fun) it's less time then the dozen or whatever steps it takes me to do it all trig. My question is how condensed can the trig get to get all these answers?My other question is who cuts irregular hips or valleys ( or long regular hips or valleys) to calculated measurements when the basic stuff is up and they can be taped? why risk it? In regard to backing bevels for hips and valleys does Marshall Gross in his roof framing book get it wrong using the drop measurements instead of the smaller square to the pitch plane measurement to calculate the saw angle? While i'm at it has anyone SWITCHED to a Construction Master calculator after having used a regular scientific calculator for a length of time? If anyone offers up trig formulas could you please do it for dummies fashion , i don't seem to get some of what are placed on this site.12/16.97 inv tan, sine, inv tan is an example of what i understand as a formula to get the backing bevel on a 12/12 hip roof.Sorry but i was a desk drooler.