🚀 go-pugleaf

"Ken Pledger" <ken.pledger@mcs.vuw.ac.nz> wrote in 
message 
news:ken.pledger-7E7134.13502417042007@bats.mcs.vuw.ac.nz...
> In article 
> <4621e020$0$16555$afc38c87@news.optusnet.com.au>,
> "Neil Green" <nrgreenNOSPAM@optusnet.com.au> wrote:
>
>> I need to make some curved rafters for a verandah
>> roof.
>> The common rafters will be 1500mm when measured in 
>> a
>> straight line from the end points with a curve of
>> 100mm, that is, the mid point of the curve will be
>> 100mm from a straight line drawn from end to end, 
>> and
>> the curve will be part of a circle.
>
>
>      O.K.  That much is clear.  You could use the 
> technical terms "arc"
> (shortened from the Latin word for "bow"), "chord" 
> (from Greek, but
> related to the English "cord" meaning a string), and 
> "sagitta" (the
> Latin word for "arrow").  A diagram makes the 
> reasons for those names
> pretty obvious.
>
>      You chord is 1500 mm and your sagitta is 100 
> mm.  Those are enough
> to calculate the radius of the circle, which I make 
> 2862.5 mm.  (If you
> want the formula for that, just ask.)
>
>
>> I need to know the curve for the rafters at each
>> corner of the verandah which are at 45deg.
>> The length is obviously 1500mm x sqrt2, but is the
>> curve 100mm x sqrt2? ....
>
>
>      That's more obscure.  Also, I didn't follow 
> your words "the common
> rafters" above.  Will you have rafters from left to 
> right, from front to
> back, and diagonally as well?  Also, your mentioning 
> sqrt(2)  suggests
> that viewed from above your verandah roof will be 
> square, not just any
> old rectangle.  I know it's hard without a diagram, 
> but could you
> explain in a bit more detail?
>
>            Ken Pledger.

Thanks Ken.
By common rafters I mean those that run at 90deg from 
the building, although there will also be one common 
rafter at each end against the building.
The verandah roof will be rectangular, 4900 long by 
1500 wide approximately, which in plan view can be 
divided into two 1500 x 1500 squares at each corner 
and a rectangle of 1900 x 1500.
The rafters I need to calculate run diagonally across 
each corner to each corner point and need to be such 
that the roof is in a plane, both across the front and 
towards the building at each corner.
The arc of these rafters needs to be different to the 
common rafters but I'm not sure how to get to it.
These rafters will span 1500(Common rafter) x sqrt2.
If this isn't clear can I email you a diagram?
Thanks again
Neil.