Bending a duct elbow to shape - GIF

[Altair]

Bending a duct elbow to shape.




Previously:

HVAC duct jack - photo
HVAC velometer - photo
HVAC filter box grabber - GIF
HVAC balometer - photo
Duct crimping drill attachment - GIF

[mwmkravchenko]

I was looking at a wood stove pipe exactly like this a few weeks ago wondering what kind of force it took to make that bend. Now I am wondering how the bellows shape is created!

[Toolmaker51]

The corrugations could be spun or rolled. Force to bend is not high, judging by spring back to 90 from over bend. The 'tools' sockets preserve roundness of spigot, directing all the effort to actual bend.
Rather conjectural yes, but not much different than water heater vent I used to correct alignment of tank with vent stack. Betting heat of a stove though, needs stainless instead of aluminum.

[mwmkravchenko]

Um As for force. Try unbending those elbows. They are seriously stiff. The material is at least 20 gauge.