Vent hood nightmare, please help!

[Bassman]

Okay, so I have about 12 inches of 7" round coming down from the roof. Then it's another foot to the top of the cabinet, then 20 inches down to the motor which has a 3x14 duct opening. I just spend another wasted day trying to make a nice connection using 3x14 duct up to a transition at the top of the cabinet, and then some 7' to connect to the stub coming down. I even tried an adjustable swivel connector thingy but I just can't figure out how to join it all together without some sort of slip-fit connector. How do you guys install duct when you can't move either end of the run? I understand flex is a no-no but I only would need a few inches. I hope this is understandable and thanks for any help.

[jadnashua]

Is it that you want to insert one end into another and both pipes are full diameter? If so, they make fluting tools (not sure if that is the right name!?) that sort of look like pliers, but makes a corregated end that would allow you to insert one end like a factory fitting.

[Bassman]

Is it that you want to insert one end into another and both pipes are full diameter? If so, they make fluting tools (not sure if that is the right name!?) that sort of look like pliers, but makes a corregated end that would allow you to insert one end like a factory fitting.
You mean a crimping tool? No, the issue for me is how to fit all the pieces together when you are working in the middle of a run. You know how you have slip couplers for plumbing? Something like that, or superior knowledge in how to use what's available. :)

[Bassman]

Apparently what I wanted is one of these:
http://www.standexadp.com/catstyle.php?searchtext=draw

Could not find one in this city for love or money, but a very helpful guy in an HVAC shop made me a band to use with sheet metal screws. Took him 2 minutes!