Start: Speak with the Dwarf Commander, who is found south of the Coal Trucks far west of Seers.
Requirements: Ability to defend against level 32 giant bats. Decent crafting and smithing, level 20 agility and 45 magic are recommended.
Items needed: Camelot and Falador teleport runes or charged dragonstone amulet are recommended.
Talk to the dwarf commander (north of the fishing guild), who tells you he needs a extra pair of hands to fix the fence to stop the goblins. You are given six (6) railings, so find the six spots in the fence by right clicking and selecting "search" on each piece of fence (1 per tile). If you fail to replace a railing, you will be hit for 2 damage. When you have repaired all 6, return to the Dwarf commander.
After talking to the commander again, go south to find a wooden Watch tower, which is west of the Fishing Guild. Go up the ladder, and pick up the dwarf remains. Go back to the dwarf commander and talk to him. He will tell you to find a boy (Lollk) that was captured by the goblins.
Next, walk by the side of the Fishing Guild past the Goblin foot prints which are pointing to Goblin Cave on the eastern side of the guild. Enter the cave entrance and you should see some goblins, rats and a couple of bats. Take the middle passage to the north-west corner. You should end up in a room with many goblins and crates on the sides of the cave walls. Search the crates until you find Lollk.
Go back to the dwarf commander and he asks you to fix the cannon. He gives you a tool kit. Go to the small house next to the commander and inspect the cannon. You need to fix the pipe, barrel, axle, and shaft. Fixing them may depend on your crafting or possibly smithing level, and lower levels will struggle, but eventually will succeed.
Go talk to the commander again and he will tell you to visit the dwarf cannon engineer. He is located south of Ice Mountain, west of Edgeville. To get inside the fence enter the house and open the door. Talk to the engineer and he will give you Nulodion's notes and a cannon ammo mould. Take them back to the Dwarf commander and the quest will be completed.
1 Quest Point
Crafting experience = (Level*50 + 250) x Custom rate
Ability to buy a dwarf cannon for 750k gp. Cannon autotargets NPCs.
Ability to make cannon balls with steel bars (lvl-30 smithing required).