Ok I admit I cheated on 3ds max - I used XSI oh noes… Anyway I don’t know if there such a thing in MAX as look at constraint, but there is one in Softimage. The basic way to do this is set the pivot of the circle to one end point of the line and create a null parallel to the circles cross section at the other end, then apply the look at constraint of the circle to the null. Then just move the null with translate tool to snap to the line and the circle should follow the null. There done.

Thanks for all your posts and sorry if it made you pull out some of your hair.

Maybe this can help a bit.
The violet line is a circle created in the top view-port, the line is rotated only in one axis
(I’m simplifying deliberately the case.)

1.  Create Protractor Helper and measure the angle.
2.  Rotate the circle with the same value.
3.  Align the rotated circle using the snap tool.

By more complex situations, more technical work is needed but the workflow is basically the same. (Don’t forget Max is a tool for artists not for engineers, or things must be good looking, not absolutely precise.) :)

ivan

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Max has both a “Look At” constraint and an “Orientation Constraint” - the latter may be able to do what you’re after but would need some setting up - much like what you described for XSI.

Max 4.2 through 2013.
XP-64 (SP2)
NVidia 9800GTX-512 (Driver 266.58).
Core 2 Quad Q6600 2.4GHz, 8Gb Ram, DX9.0c.