Rigging and Mesh Messing Up

I’m trying to bend this mesh like an elbow, but it deforms the mesh so much it goes from this:



to this:

http://www.pasteall.org/blend/40217

Attachments


Post the .blend file, could either be the armature or the mesh (mesh needs to be modeled to accommodate deformation)

http://pasteall.org/blend/40213

Here’s the link right here: http://pasteall.org/blend/40213

http://pasteall.org/blend/40213

Edited with link to file.