birds mouth

[zed35467]

can someone tell me the process of making a birdsmouth cut, i have tried it a it seems really complicated and have wasted a lot of timber trying to get it right and am at my wits end.

 

[empip]

Have a look in here there may be something of interest
http://ca.geocities.com/xpf51/
seems to be some knowledge here too.
http://www.ebuild.co.uk/forums/messages/774/4260.html?1113494544

 

[masona]

Once you have the angle of your roof then one side of the birdmouth is the same angle which should be the same as the fascia side then come off 90 degree of that, the picture shown of the birdmouth is too big The corner or the point of the birdmouth should be no more than 1/3 width of the timber. The picture is showing 50% cut

 

[Joe Bartok]

zed35467: This probably isn't what you're looking for but ... I do all my Rafter Dimensiong by calculating the cuts using trigonometry.
This Hip/Valley Roof Calculator will help you determine the angles. It's still "under construction", has been for the past year and probably will never really be finished. The lengths are to the theoretical centerlines of the rafters and ridges. There are links to diagrams and other web based calculators.