Carrying out a birth gives you the guarantee of being able to place it at the desired place. This also limits the joints and welds in the length of the gutter, which reduces the risk of leakage. Prefabricated parts are expensive, you will realize substantial savings.
The diameter of the opening of the birth depends on the diameter of the first element of the descent: a frustoconical sleeve sold especially. Be careful not to create a rainwater brake by a throttling that would lead to overflowing in case of heavy rain and could hold plant debris.
Cut to the diameter of the birth
Position the cuff at the desired location and trace the inside diameter of the birth. Split the part to be removed with the jigsaw then deform it. Pass the nibbling shears, cut out the circle.
Insert the sleeve and solder
Pull the cuff into the inside of the gutter. Apply stripping flux on both pieces, then make a regular solder bead on the outer junction.
Create a natural fall
Flip the gutter. Through the interior of the gutter, hammer the zinc to create a natural fall (the edges of the metal down). Use a heavy body mallet or heavy tool handle.