What is the easiest way ... ?

[trevtheturner]

Hi, Dog,

If shooting it first proves difficult - 90mm wide x 170mm high should be about right (serious answer!). Hope this helps.

I know it was a serious question but I don't quite get the connection between a ringpull and a dovecote - is it because it is for ring-doves :?:

Cheers, Trev.

 

[Dog]

Thanks Trev.

There is no connection whatsoever between ringpulls and doves but instead of filling the entire forum with my questions I decided to add them to this thread plus there is a lot more interesting threads that'd be pushed down the list if I continue posting new threads each time I want to ask something

 

[Dog]

Back again...I'm getting somewhere with this Dove Cote at long last but I have a problem with angles. The roof timber is 10" wide x 2' long, the body of the Dove Cote is 23 3/4" diam. in octagonal design. I need to work out what angle to cut the roof timbers, which will also be octagonal in design, I don't need the angles to make it octagonal but I do need the angles at which to taper the roofing timber, any easy way to do this ? If that makes any sense at all :?

 

[Martin]

Dog,

Sticking my neck out (to be chopped off by someone who's much better at maths than me ) I reckon the angle you need is 11.768 deg :idea: (or 78.23 deg depending on which way you look at it) - or thereabouts (probably some rounding errors in my calculations).

I assume that you want the roof to end in a point (this makes it easier) and that you want to use the existing lengths (24") and widths (10") of the wood to construct the roof pieces.

If you imagine cutting each peice you end up with in two along their length you'd get two right angled triangles. Harking back to school days, pythagoras' theorem states that for any right-angled triangle with lengths a, b & c that the following must be true:

c*c = a*a+ b*b (where c is the longest side)

The length of the longest (sloping) side is therefore the square root of (24*24+5*5), or 24.5153. With this, we know that the angle opposite this side is 90deg (because it's a right angled triangle) and can use the "law of sines" to caculate one of the other angles (which states that for any triangle, the length of a side divided by the sine of its opposite angle is the same when applied for any of the other sides/angles). Or....

a/sin(A) = b/sin(B) = c/sin(C) .... where a/b/c are the lengths and A/B/C are the oppposite angles

Are you still with me :shock: (I'm not sure I'm with me but I'll rattle on anyway :? )

So, if we know that the longest side is 24.5143 and the angle opposite is 90deg then we can deduce that...

24.5153/sin(90) = 5/sin(B) ....where B is the angle we're trying to find...

Working this through, we get...

B = arcsin ( (5*sin(90)) / 24.5153) or 11.768deg

If you were worried that your last post didn't make sense then I've probably put that fear to rest - at this rate they'll be carrying me off to the cells with padded walls... :roll: It's kind of difficult to explain this in text form only, but hopefully it makes sense... Of course this only works if the lengths of the roof peices are long enough to form the point (which in this case they should be).

For what it's worth, I usually end doing this sort of thing using a CAD package (because I'm lazy and it's more fun that way) - but I saw your post and couldn't resist the challenge...

Hope that helps (but probably not the simple answer you were looking for)...

Cheers,
Martin.

P.S. the CAD package I use is called TurboCAD, which I can very much recommend. Excellent peice of software...

 

[Dog]

Martin said: 'I assume that you want the roof to end in a point (this makes it easier) and that you want to use the existing lengths (24") and widths (10") of the wood to construct the roof pieces.'

I do indeed Martin, and thank you for doing the maths for me, your post makes more sense than mine to me, and I wrote it :lol: