I soldered 1/2 inch drop ear elbow to the copper pipe coming out of my shower valve that I just installed. Everything has been tight but it is leaking at the threaded female connection of the drop ear where my shower arm is threaded in. I put plenty of Teflon tape and tightened it all the way down where the shower arm is angled downwards. Is there any other fitting that should be used here or is it probable that I just have a bad drop ear?
Obviously it could also be the shower arm threads are bad. When you thread in the shower arm do you get resistance after a few turns or is it loose until it suddenly hits the end of the threads?
Some people use both pipe dope and Teflon tape.
Alternatively, you can use "plumber's hemp" and use it in conjunction with pipe dope. Hemp may work better with loose threads. Hemp is used in Europe for parallel threads. US tapered threads normally don't need hemp, but sometimes it does the trick. Google for a Youtube video on how to apply it.
I wonder if heavy duty sewing thread would serve as well as the plumber's hemp?
Check for a crack in the fitting. Brass fittings are cast and then machined. A flaw in the casting can result in a crack that is caused when tightening in the pipe. It's difficult to see with the pipe removed and with the drop ear behind a wall you'll have to look with the pipe removed from the inside. You may as well check as you need to remove the shower stub to reapply a thread sealent. Teflon tape (the orange/pinkish one) works well for sealing. Wrap it around the same direction that it threads. So holding the pipe in your left hand looking at the threads you would wrap it, slightly stretching it, clockwise from the first threads up the threads towards your left hand overlapping by about 3/4 width.