The trick is understanding that the MFR Harvester thinks that all those trees are connected.
It'll go through connected logs, and leaves, and anything "close enough" and then start at the farthest away place that it can reach.
When combined with how HUGE the large oak can grow, you get yourself quite the chance of a breakout.
Leave yourself a firewall of 4 blocks on all side of the area you are raising trees in. MORE if you are using oak, much more. Try 10 or 12.
Make sure that there is no logs of any kind, or leaves of any kind in your buildings in the area.
And above all, don't panic.
It'll go through connected logs, and leaves, and anything "close enough" and then start at the farthest away place that it can reach.
When combined with how HUGE the large oak can grow, you get yourself quite the chance of a breakout.
Leave yourself a firewall of 4 blocks on all side of the area you are raising trees in. MORE if you are using oak, much more. Try 10 or 12.
Make sure that there is no logs of any kind, or leaves of any kind in your buildings in the area.
And above all, don't panic.