https://forums.autodesk.com/t5/inventor-forum/how-to-line-up-the-middel-of-two-parts-in-an-assembly/m-p/5799304#M362124 Normally you can constrain the Origin axis or planes for that (depending on how you made the parts). If it doesn't work it is probably because there is already another mate present that interferes. Wed, 02 Sep 2015 09:10:56 GMT Frank-Oosterwaal 2015-09-02T09:10:56Z