I am trying to make a drill, where I got 3 blocks: IronBlock (IB) - Chest (C) - Furnace (F). The IB has to move forward, the C then takes in the IB's place, then the F takes in the C's place. This is what is supposed to happen, but I get an error when I try to move the F to the C's place (moving the IB and the C goes ok). The error tells me that it can't cast a furnace to a chest... My code to 'move' the block is setTypeId() and setData(), so: Code: chest.setTypeId( furnace.getTypeId() ); chest.setData( furnace.getData() ); Why does it gives an error? How can I work around this to make this work?