I ordered some inside-mount solar shades from Blinds.com. They come with mounting brackets that need to be installed very close to the side frames. I want to drill pilot holes before putting in the wood screws that are 1.5 inches long. The challenge is, I cannot hold the drill perpendicular to the top frame because the drill chuck hits the side frame. Though the window frame appears to be wood, deep inside there is strong resistance. It took me quite a while to drill a pilot hole that was close to 1 inch deep. Not sure what is inside the frame, but it does not feel like metal.
I have not found a drill with a chuck that is small enough to fit into the confined space. Do you have any drills to recommend? The radius of the chuck needs to be smaller than 5/8 inches. Is it possible to use a Dremel to drill the pilot holes?
I ended up using the following setup, which worked great.
Here are two pictures of the shades after installation.
Thank you all for the suggestions!