Choppers are a machine in Progressive Automation. They use axes to chop down trees. They will also break leaf blocks and collect saplings, and when they cannot find any trees in their operating area they will plant saplings around themselves.
Like all Progressive Automation machines, Choppers can consume any standard Furnace fuel, or Potatoes, to function. Alternatively, if Redstone Flux is available, the RF Engine can be placed in the Fuel slot to consume RF in stead of fuel. By default (configurable), Choppers consume 40RF/t and can hold 40,000RF. In order to operate, Choppers also require an Axe of a tier equal to or below their own. (Wooden Choppers can only use Wooden Axes; Diamond Choppers can use any Axe.) These tools are used to break blocks as though a player had used them, and as such the working speed of a Chopper is dependent upon the tool it is using. As higher tier Choppers can use higher tier Axes, and higher tier Axes tend to break wood more quickly, higher tier Choppers can be more fuel-efficient. Tools from other mods can be used, so long as their material tier matches that of the Chopper used. Tools from Tinkers' Construct will not be destroyed when their durability depletes, however a Chopper using a broken tool will operate very slowly. When breaking leaves, it is done as though a player had broken the leaves by hand, and no Axe durability is consumed. Choppers chop trees from the top down, one level at a time, leaves first, circling inward to the Wood.
The GUI of the Chopper contains 4 input slots (Saplings, Fuel, Axe, Upgrade), a 3x3 grid of output slots, a fuel burn indicator, and an information display area. Upgrades placed in the upgrade slot will be immediately consumed. When inactive, the display will show why the Chopper is not currently active. When active, the display will show whether the Chopper is actively cutting trees or is 'Waiting' for new trees to grow within their area. If a Chopper's Fuel slot is empty, Wood that it collects will automatically be placed in the Fuel slot.
Choppers will attempt to automatically output any items in their output slots into adjacent inventories. This behavior can be changed on a side-by-side basis with the PA Wrench to allow sides to accept new Fuel or Tools, allowing the Chopper to potentially be completely automated.