[Tutorial > Modeling] Curved Hip Rafter Tutorial
-
Hey Folks
Someone on one of my Construction Forums was asking "Does anyone know how to calculate the length and radius of a curved hip (in this case an s-curve) rafter. The application is for a plaster vent hood frame".
he had the two radius's (radai?) for the S curve.
He got some answers, here's one.
"Anyway, If you make a line from peek of hood to soffit, determine the rise and run, then you will be able to calculate the hip.Then, using the line from peek to soffit, plot the curve by dividing the line into x number of pieces.
Now the hip will be proportionally longer than your rafter. Multiply your OC spacing by this ratio to get your hip OC spacing. transfer the altitudes and you got it.
It's either that or scribe it in place using a straight edge."
"If the diagonal for the rafters is 36 and you divide it by 36 while plotting the altitudes, then by dividing the hip by 36 and using each altitude from the rafter to plot the hip you'll be fine.
Say from peek to soffit the run is 12"
The rise is 24"
this is a 24 pitch. the diag is 26 13/16" divide this by 12 is 2 1/4".
plot the s curve from the 24/12 at 2 1/4" intervals.
the hip will be 29 3/8" divided by 12= 2 7/16 intervals
all altitudes are the same."
way too difficult I thought, here's my answer ..
"That's pretty easy to draw using SketchUp David. Do you have a profile or elevation drawing of the hood frame? If so maybe I can help you out." Luckily he did have a SUp model for me to work with.
and here's the tutorial I made for him.
-
Nice response, Joe. I start to get a headache even looking at the written procedure you quoted, and I'm an architect.
--Lewis
(Lewis Wadsworth)
-
yeah Lewis, I was reading all that and thinking how easy it is to do in SUp .. just draw it to scale, and it'll work/fit perfectly! probably took me 5 minutes to draw, and I even gave him a full sized template to print out.
No way I could be designing and building some of the things I do without SUp ..
-
@joe wood said:
...he had the two radius's (radai?) for the S curve...
Well, I'm not an architect so it was even more complicated for me to go through but the Latin plural for "radius" is "radii"
But I understood the "tutorial" - well, who says SU is not intuitive at all?
-
Boy Joe, you've come a long way baby!
-
Long way is right Susan. Remember when I first showed up? Didn't know anything about computers much less using any kind of programs.
-
Yes Joe I remember only very well. That is why I am so very impressed. You can teach me a few things now!
Advertisement