The Dredge

The Dredge digs a tunnel and picks the ore out of its walls on its own while you are busy with other things. Put a pickaxe in its wheel and give it a redstone signal — it gnaws a tunnel ahead step by step, up to 64 blocks. The pickaxe's enchantments work — Fortune, Silk Touch, Efficiency, Unbreaking — and the pickaxe wears out.

Above all, it sifts: ore within two blocks of the tunnel — in the walls, floor and roof and behind them — is picked out on the way. With Vein on the pickaxe it takes the whole connected vein and digs up to 96 blocks.

Choose the cut in the Dredge's window — use it empty-handed: 1×2, 3×3 or 5×5, and 7×7 with a Survey III lens in the wheel. The wider the cut, the more blocks a step and the more flux it costs; the wheel takes one block at a time, so a wide tunnel takes longer. Sweep on the pickaxe takes 3×3 of the cut in one blow.

A cut Conduit lens goes into the wheel's hub — use the lens on it; its nodes change the work. Scorch smelts: ore comes out as ingots. Chill freezes water and lava around the tunnel without spending stone. Crack splits soft rock faster, Excavate takes blocks whole, Reverb gives ore an echo of Fortune, Fork sifts four blocks out. Each costs flux; a cheap lens muddies as well.

Holes, water and lava around the tunnel are sealed with its own stone — the tunnel neither floods nor caves in; every eight steps it sets a torch if there is one in the chest behind it. The spoil goes into that chest: valuables first, then rubble; when the chest is full it waits and spills nothing. Every block costs flux from the chunk being dug, and the deeper, the dearer.

A Stow sigil painted on the chest behind it decides what to keep: its filter is what goes into the chest. Rubble the filter refuses, the wheel grinds away — rough work that leaves murk in the chunk; ore and anything of value is never ground: what the filter refuses goes down the chute.

Put the Dredge on a minecart and the tunnel no longer ends at block sixty-four. The Minecart with Dredge crawls along the rails, and where they end it digs a cut, sifts the ore out of the walls, lines it and lays a rail from its own box. Only the rails and torches in its box, the pickaxe and the flux hold it back. It does not haul rock — it grinds it (murk in the chunk); the box is for ore. A powered activator rail stops it.