I need to put a bead on the ends of short lengths of 1.5 x 16swg
aluminium tube.
it's for joining car radiator hoses.

I knocked up a beadroller, it's nice'n'stiff, and everything
seems to work nicely[untill you put a tube in it], far better than the
large one I made for use on sheet..
I made the internal roller with a 60thou 'hump' approx 60deg one side
and 30 the other, the top was radiused with a file; the roller has a
step
about 8 mm from the hump to positivly guide the tube. the top roller
was just groved .125" wider than the widest part of the hump, when the
whole thing was smoothed off and polished..the bottom
roller is in ballraces and the top is in a wide broze bush and it's
all shimmed to keep them aligned.

the problem with the first internal roller was cracking on the crest
of the bead formed, it made a nice shaped bead that had a steeper
angle one side, just how i intended.
I altered the roller so it is symetrical and enlarged the
radius on the crest, it's still cracking on the crest of the bead. The
tube is almost imposible to direct, I have done abpout twenty beads
and only one or
two would be acceptable. On one I have driven the tube up onto the
step behind the die and opened the end up, it looks pretty good but it
wasn't meant to be like that;-)

The tube is an extrusion and I cut some bit from it and folded them to
see if it wqas maleable enough and it seems OK, I will annneal a bit
tomorrow and see if that's the problem.

I wonder whether a simple guide a few inches in front of the rollers
with vertical slot, in line with the rolers, the width of the tube to
be rolled would be enough to keep the tube straight?

Does any one do this and how do they do it?
what alternatives to the roller are there?

--
richard