A hard to craft machine which can recycle items. Put something in and there is a good chance you'll get some parts used to make the item.
You can only put craftable items in. Meaning torches, ladders, etc will work. But mob drops, treasures, etc will not work.
To put an item in simply tap the junk machine while holding the desired item in your hand.
It is not possible to uncraft any type of hammer in the Junk Machine.
In 1.2, It is possible to produce a net gain of certain recycled items, given your luck. Coal and all metal(using bars or nails) are two examples of this.