Thanks for the info, once again, I saw the vice marks on your's and knew they must be very soft. I figured you, as a machinist, knew just how soft they were and still ended up with some vice marks on them. I figured mine would look the same when I was done.
I guess I should fab up some aluminum vice jaw covers for this type of work. I screwed the tube fittings in the end first too, and used the minimum force to hold them steady while drilling and tapping. The tube nuts still screw in and out with ease still. Did you notice I got the 1/8" male /male fittings without the nut in the middle? They were out of those, and I hope I don't have an issue when I screw the adapters into the radiator using the larger nut on the end. I'll use Loctite fitting sealer (not the normal red or blue, but the one made for fittings and pipes etc) when I install them.
They should be pretty strong now using your technique. I picked up a $50 tubing bender from Summit a few weeks ago. They look similar to pliers. I've used the cheaper hand held benders before and ended up with some near kinks in my 90 degree bends. I didn't want that to happen again. I also ordered a 25' box of 5/16" tubing. If I mess up making my lines, I will have another chance or two.
Are these flare fittings on the cooler lines double flared like brake line ends, or are they single flared? I can make either ones.