Originally Posted by Doug Fattic

Yes there is a structural advantage to making an ellipse shape. This distributes the stress of the joint over a much larger area so it is less likely to break at the sleeve edge. The worst shape would be to cut the sleeve straight off making it have a much higher stress line. In addition I milled some slots in the sleeves. This was to make it easier to braze. Beyond the basic shape I used, it is possible to add even more detail to the shape. This can be for decoration as well as stress distribution. In theory the longer the sleeve edge the greater the distribution of stress over a larger area.