I need to do a sreis of 90 degree bend in copper how do I find the centres to get it exactly right

I know how to do it with electrical conduit.
If you have a scrap piece of copper, Mark 1" marks along pipe before bending, then bend and see how much to subtract or add your instances.

i need to do a sreis of 90 degree bend in copper how do i find the centres to get it exactly right
What size and thickness of copper tubing are you uusing?
Please explain "series of 90 degree bends". How many bends are we talking about? For what? Are you asking how to bend soft copper or how to set up a jig for multiple bends? Can you put a drawing of what it is you wish to do? Regards. Tom

Please respond to Tom's questions, I am sure you will need a copper tube bendding tool, Thanks.

John

How critical are the bends ? What's the size of the sweep ? What size of pipe ?

We bend soft copper using either a copper pipe bender or copper bending springs. (see images). It's also possible to fill a copper tube with sand and make a 90 that way,( old plumbers trick). Answer the above questions to get a complete reply. Good luck, Tom