Factorio Forums

TL;DR
The Biochamber should default to jelly recipe when crafting rocket fuel.

What?

I expected the biochamber to default to the rocket fuel from jelly recipe. It doesn't. I defaults to the assembling machine version that uses light oil and solid fuel. It seems more consistent to me to use the biochamber specific recipe as the default. (Also, this makes my gleba setup work, lol.)

Why?

I'm trying to setup a circuit where the biochamber crafts whatever signal is sent to it. This works pretty well for most of the time. If I send it a plastic signal, it picks the bioplastic recipe which uses mash and flux. It doesn't pick the chemical plant recipe which uses coal and petro gas. This is inconsistent and unexpected.

I think the suggestion if implemented would make life easier.

I think it may be possible in some situations to circumvent the problem mentionned by adding a decider combinator and a dummy arithmetic combinator to make sure the signals stays in sync. Then the arithmetic does each + 0 => each, and the decider rocket fuel > 0 => output [rocket fuel : - 10000] [ Rocket-fuel-from-jelly : 1], a high negative signal to mask the rocket fuel, and instead the signal that correspond to the specific receipe with jelly for the biochamber.

mooklepticon wrote: Sat Feb 07, 2026 7:14 pm If I send it a plastic signal, it picks the bioplastic recipe which uses mash and flux. It doesn't pick the chemical plant recipe which uses coal and petro gas. This is inconsistent and unexpected.

This is because the biochamber can’t craft the vanilla plastic recipe. If it could, it would also default to it upon receiving the plastic signal. And it can craft the vanilla rocket fuel recipe. So that’s why the behavior is different between rocket fuel and plastic.

But there is a recipe signal specifically for the bio rocket fuel recipe. I don’t know the full context of your setup, but it should be possible for you to use that signal.

To be honest, I had no idea the biochamber automatically interprets the plastic signal as bioplastic. I always assumed you would have to send it the bioplastic recipe signal.

mooklepticon wrote: Sat Feb 07, 2026 7:14 pmI'm trying to setup a circuit where the biochamber crafts whatever signal is sent to it. This works pretty well for most of the time. If I send it a plastic signal, it picks the bioplastic recipe which uses mash and flux. It doesn't pick the chemical plant recipe which uses coal and petro gas. This is inconsistent and unexpected.

To further drive the point home... there isn't a recipe signal for the vanilla recipe. So if you special cased the Biochamber logic to reinterpret a rocket fuel signal as a request for the biofuel recipe rather than a request for the default recipe, it would be impossible to set the default recipe with the "set recipe" functionality.