1. Normally accepted maximum bend radius is 4 x pipe diameter, so a minimum radius of 60 mm for 15 mm pipe.
2. You can bend 180 degrees with a spring. It can be awkward to get the spring out afterwards, but grease it a bit before use, then twist it to "tighten" the spring usually works.
3. The difficulty will be getting a smooth curve. You could use a wooden (MDF) former curved correctly. There'll be a bit of spring back, so make the radius of the former a bit smaller than the required curve.
4. While you can bend normal (half hard) 15 mm copper pipe with a spring, its much easier if you anneal it first. Just anneal the bit which is going to be curved.
5. With the right bender you can bend it with no difficulty at all. See if you can find someone with an old fashioned stand bender. Most of the modern hand held ones won't do 180 degrees.
2. You can bend 180 degrees with a spring. It can be awkward to get the spring out afterwards, but grease it a bit before use, then twist it to "tighten" the spring usually works.
3. The difficulty will be getting a smooth curve. You could use a wooden (MDF) former curved correctly. There'll be a bit of spring back, so make the radius of the former a bit smaller than the required curve.
4. While you can bend normal (half hard) 15 mm copper pipe with a spring, its much easier if you anneal it first. Just anneal the bit which is going to be curved.
5. With the right bender you can bend it with no difficulty at all. See if you can find someone with an old fashioned stand bender. Most of the modern hand held ones won't do 180 degrees.
