I am trying to generate a helical trimer from the monomer pdb around a central double-stranded RNA. The rise and twist are 46 A and 74.0 deg respectively. I opened my monomer pdb in chimera (Screenshot-0) and used the following command to generate an axis around the central RNA double helix:

where X and Y are the chain IDs for the 2 RNA strands

This command helped me generate an axis named a1 along the RNA duplex (Screenshot-1). Now I want to generate a helical trimer along the RNA duplex with rise=46A and twist=74deg. For this I used the command:

However, it is not placing the symmetric copies around axis a1 but around a distant axis (Screenshot-2). I am not sure how to generate the helical trimer along the a1 axis. Any help in this regard would be appreciated. Thanks.

-Sadeem

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