The easiest way to get cracked corn cobs for most folks, is to buy
them. However, if you’ve got any friends who are farmers they may be
able to help if they’ve got a hammer mill.
Running cobs through a hammer mill with a coarse screen installed
will grind the cobs into the size you’re looking for. There are a
number of different size screens that can be placed in a mill
depending on the size of the desired finished product.
In the event you don’t have a farm friend, you might also check
companies that mfg. animal feed or feed lots that feed large numbers
of animals. They also usually have hammer mills.