Molten metal and casting

Molten metal is plumbed, never carried in a bucket or a stack. It leaves a furnace tap into a canal and flows cell by cell to wherever the canal was built to go, and it is cast at the far end. The one thing a player does carry is a filled mold, and that is where the burns come from.

The canal run

A canal is not a pipe with one shared pool. Each block owns the metal standing in it, and each second some of it moves to the next cell along.

Quantity	Value
capacity of one canal block	50 units
flow across one connection	up to 50 units per second
smallest transfer worth making	10 units
drain speed at a canal tap	20 units per second
Molten barrel capacity	800 units
large mold capacity	100 units
cooldown toward ambient	24 C per second, toward 20 C

Because every cell is its own vessel, a long canal takes visible time to deliver, and a canal left standing full goes solid where it stands. Flow direction is decided by which of two neighbouring cells holds more, not by which end the furnace is at, so metal runs back toward the canal start whenever the downstream cell is fuller. Slope is not modelled: a canal can run level, but every cell must touch the next, and a gap stops the run.

The family is four transport shapes and three endpoints. The canal start sits under a furnace tap and takes the runout, and it is also a valid target for a hand pour from a vanilla smelted crucible. The straight shape doubles as the run's valve: 4 fire clay seals a straight cell into a separator that severs the run there, and a chisel breaks the seal again and refunds 2. Sealing is refused unless the cell and every canal neighbour on its connector faces are empty, so a seal can never trap metal against itself.

Cobblestone, coloured running brick and fire brick each cut the whole family of canal shapes, and which of them a run is built from is cosmetic. One diagram plus the material makes the shape, which is what keeps a whole family off the crafting grid; see Diagrams and the design table.

The three exits

Molten Canal (Tap) pours down into whatever is parked beneath it. Sneak plus right-click with an empty hand parks a Molten barrel or a large tool mold, or retrieves what is parked with its contents; ctrl plus right-click toggles pouring. Parking needs a real solid surface directly below. A barrel takes metal even after the metal in it has hardened, because it re-melts; a mold does not, because a hardened mold is a finished cast.

Molten Canal (Mold Pedestal) fills one small tool mold standing on it, on the same modifier scheme. It drains the run straight into the mold with no rate of its own.

The sand casting stations pull metal out of an adjacent cell themselves rather than being poured into. The Sand Casting Cell and the Sand Casting Bed pull 25 units per tick from the face they are drawn to take it on.

Heat, molds and burns

Clay is the ceiling of the ceramic tier. A small fired-clay tool mold shatters instead of casting when the metal poured into it is above 1100 C, which sits between the vanilla casting metals and the iron family, so it bites only on iron pours. It shatters with no drop and a crack that every player within 8 m hears. Large anvil and helve-hammer molds are exempt, and the mod's own Cast Iron Ingot Mold never shatters.

A filled mold can be picked up, which vanilla's cannot. Two things follow:

• Carrying one bare-handed burns at 200 C of content and above. Gloves stop it; tongs do not, and never will, because a mold is held in two hands.
• A mold taken into anything but an empty hand spills. Put it in the active slot and leave it there until it is set.

The mod's own cast molds always have this handling. Vanilla clay tool molds get it only when EnhanceVanillaMolds is turned on, which is off by default; turn it on live with /exmod config iiex EnhanceVanillaMolds true.

A cast-iron mold body soaks up 0.7 of the poured metal's temperature as its own glow and sheds it at 25 C per second. Pulling a mold off a pedestal and setting it on the ground cools the cast faster than leaving it under the run.

Sand casting

Sand casting is the route out of cast iron, which cannot be forged. The cell and the bed both work green sand, which is sand blended with clay and damped so it holds an impression: 8 sand plus 1 blue clay makes 8 Green Sand.

The pattern is the specification. A Pattern carries what to cast, the station reads it off the held stack, and nothing in the station's code names a shape or a product, so another mod adds a castable part with a pattern definition alone. Patterns are carved from a reusable Diagram, a knife and 2 planks.

The Sand Casting Cell casts capital goods, a handful at a time: iron molds, heavy plate, barrel blanks, cast shells and wheel sections. Its loop is two clicks and a wait.

1. Place the cell and right-click it once with Green Sand. The sand is rammed in and is never taken away again.
2. Right-click with a Pattern. The impression is rammed up and the pattern takes a point of damage.
3. Let the run fill it through the launder face, which is the face the spout is drawn on.
4. Wait for it to set. An empty hand on a cell still holding liquid metal is refused.
5. Right-click with an empty hand to shake it out. The part comes out, the impression is destroyed and the sand rakes back to full.

A pour that came in below the pattern's minimum temperature, or that ran short, hands back recovered scrap of whatever metal was in the cavity instead of the part.

What goes wrong

A canal cell has gone solid and the chisel is refused. A cell latches solid the moment its metal drops below its melting point, but it cannot be chiselled until it is below 30 per cent of that. For iron that is the whole span from 1482 C down to about 445 C, and during it the block reports that it is still cooling. Wait; the tool is right and the timing is not.

Metal solidified at the tap. A tap with nothing under it pours onto the ground and sets there. Put a canal start under the spout before opening a tap, or accept chiselling the plug out by hand.

A junction is filling the wrong branch. There is no routing. Every connection moves metal toward whichever side holds less, so a branch drains in whatever order the fills happen to fall in. Seal the branch that should not fill, or tap it shut.

The furnace stalled while the canal was full. That is the back-pressure chain working: a full destination backs the run up cell by cell to the canal start, the furnace cannot push into it, and a full product pool counts as a disruption toward extinguish. Drain the run before the pool fills.

A mold on a pedestal shattered. It was fired clay and the run was above 1100 C. Iron needs an iron mold, which is what the Sand Casting Cell is for.

Metal disappeared out of a mold. It was picked up into a slot that was not the active one, or the active slot was swapped while it was still liquid.

Something poured that has no solid form. When a metal's solid drop cannot be resolved the mod hands back a block of Solidified Slag rather than destroying the charge.