Hi Harry, Awhile back I simply cut a deep groove of the required radius and width in a lump of round bar and held it in the vice to bent the pipe round it worked fine ! Noel.

I suspect bending grade just means soft enough to bend without issues so may just be fully annealed. You can, of course, anneal copper yourself just by heating it to a high enough temperature and letting it cool down.

As for wall thickness the thicker the wall the easier it is to bend to a tighter radius without wrinkling but then you lose out with a reduced bore. A thicker pipe will also be more resistant to mechanical damage on a model. If you stick to a minimum bend radius of three times the outside diameter then choose your wall based on other factors such as cost, flow rates and forces that the pipe will be subjected to in use. Thin wall may be fine for cold water or low pressure but not for high pressure steam for example.

Martin C

The one on hemingways site looks quite nice