In researching the related question How can I break items down into their components, I saw a complaint on Reddit to the effect that the extra, leftover materials get destroyed.
Why this is a common belief
Many people seem to believe this, and there's a good reason for that: it's confusing. And it's confusing for two reasons:
- The composite item is removed from your character's inventory, but the leftover components are placed in the Workshop's inventory.
- There's sometimes a delay before the leftover components reappear. If you want to speed up the process: go into Workshop mode, try to build something, and then exit. This appears to force the Workshop to update its inventory contents list.
Go, science!
I settled the question with science. I've tested this with various items a dozen or so times using the Armor Workbench, the Weapons Workbench, and the Workshop crafting menu.
The leftover components have always (so far) appeared in the Workshop inventory, but there's sometimes a delay.
Here's one of the experiments:
Experiment
- Remove all Lead from your inventory and the Workshop's inventory.
- Add two pencils to your inventory; each pencil has 1 Lead and 1 Wood.
- Go into the Wood Structure crafting menu—not to craft anything but just to check your Wood component count.
- Craft a Radiation Emitter, which among other things requires 2 Lead.
By creating the Emitter, we force the Workbench to dismantle the pencils, which liberates 2 Wood and 2 Lead.
If our Wood component count goes down, wood has been lost/destroyed. If it stays the same, our 2 "potential" units of Wood have simply been converted into 2 actual units of Wood.
Result
Our Wood component count remains unchanged. So unneeded materials are retained, just as though you'd broken the item down yourself.
It sounds like you're bugged. You could reload to an earlier save and have another go but since you're fine with console commands...
I don't know the quest ID for the quest you're on so what you'd need to do is open the console by pressing ~ or ' and then type sqt to generate a list of all current quest targets, this should reveal to you the quest ID for the bugged quest. Then you can do completequest <QuestID>, which will complete that quest.
Best Answer
From the wikia, the possible items you can get are:
Models
Aid Items
Junk
Other
There does not seem to be a proven formula for drop rate of any of these items, but it is worth noting that you are able to reload a save if you get an undesirable item, in order to try to get a better one.