I have a part that has no feature tree, but I need to change the angle of a chamfer from 45 degrees to 20 degrees. I can't show the part because of confidenciality stuff but I can describe it. Start with a cylindar, that ends in a dome. then shell it, so a hollow bullet shape, then from about the mid point to the dome there have been 6 teeth cut, 3 on one side 3 on the other. the teeth are not symmetric they are offset. the Chamfer is on the inside edge of the cylindar to give these teeth cutting edges. I tried re-creating it and I can get everything made except I can't get the chamfer to work. Can I just use the original solid model somehow, even though it was imported and has no feature tree?

Well thank you for your suggestions...... We managed to use FeatureWorks, which revealed another layer of Import, which we could not successfully undo, I think we are just giving up..... Again thanks for all the help.