Inventor Sheet Metal Cuts 1

I am having difficulty doing cuts in sheetmetal parts that have been rolled

I am trying to design a cyclone from 10 GA. I can't figure out how to make a (correct)circular cut tangent to the main body.

I can make the cut but the cut edges are not "true" and so the sheet metal will not go to flat pattern.

I could make the cut in the flat sheet first, but it's not a true circle so it is incorrect when I roll the part.

I hope i understood u correctly. This is how i would do it :

1. Make a workplane trough axis of cone
2. Design in this workplane a sketch with size of ur cut
3. Revolve sketch with cut on and choose an angle

In that way u have a cut with straight edges.
Dont know how ur flat pattern will react to it though.

Thanks for getting back to me. I could send you the file but I'm not sure how - on this newsgroup.

I have a 10 GA steel plate, 40 inches tall, rolled 180 degrees (15" R)(half of the cyclone barrel. The barrel axis is vertical. I then need to take an 18" diameter tube and insert it tangent (horizontal) to the 30" barrel.

I tried out ur situation (at least what i think u want) and understand ur problem now. When i ask to make a flat pattern he finally says : "no bending zone found". This is because i couldnt find no other way then making a cone with partfeatures

There is a software solution though : "Autopol unfolder" : works with inventor 7 and 8 : u can see information on it when u go to the Autodesk site.

I am on a dutch forum about inventor also and will ask ur question there. Maybe there is a freeware solution.