MatthiasWandel | Splicing wood end to end to make a long curtain rod @matthiaswandel | Uploaded March 2021 | Updated October 2024, 1 week ago.
When the longest piece of wood you have isn't long enough, and you need a strong joint to make it longer, a scarf joint or similarly angled joint is a good way to join pieces end to end.
woodgears.ca/curtain_rods/spliced.html