DataNumen File Splitter is a freeware app to split and join files. You can also compare files or verify the checksum.
DataNumen File Splitter makes the entire process simple.
The interface gives you four options:
Split Join Compare Checksum
Once you choose split, you can locate a file (drag-and-drop sadly isn't supported) and choose a location.
We used the executable for this program for our tests.
Pick how many files you want to split, and if you want to use Bytes, MBytes, KBytes, or GBytes. Oddly, although I chose two files, it split them into three. That said, when the files were rejoined, they worked perfectly.
Note: VirusTotal shows two flags from Jiangmin and Zillya, but are those programs are virtually worthless and shouldn't be on VirusTotal.