From Minetronic ~ Wiki
How to make butter:
- Place the butter churn.
- Right click on the empty butter churn with a milk bucket.
- Right click x4 with a Stamper on the filled butter churn.
- Wait 12 minecraft hours(12 000 ticks, 10 min) for the process to complete.
- Right click once on the butter churn to collect your butter.
Butter can be obtained by making it in the workbench With 1 milk bucket and 4 sugar.
x1 Milk bucket