Formatting SD Card for Marlin / RAMBO

I have been happily printing from my SD card for a while but after pulling out the card too early one time, I had to reformat the card to get it to work. Unfortunately, RAMBO is super particular about how to format the card.  Here is what I did which eventually got it to work on a Mac:

1) First I have to figure out which disk is the SD card. I opened the Terminal in OS X and typed "diskutil list". This is what I found:

/dev/disk0

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *251.0 GB   disk0

   1:                        EFI EFI                     209.7 MB   disk0s1

   2:                  Apple_HFS Macintosh HD            190.1 GB   disk0s2

   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

   4:       Microsoft Basic Data BOOTCAMP                60.0 GB    disk0s4

/dev/disk1

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:     FDisk_partition_scheme                        *4.0 GB     disk1

   1:                 DOS_FAT_32 SCJ                     4.0 GB     disk1s1

The primary drive is disk0. The SD card is disk1 and the primary partition on that disk is 1.

2) Unmount the SD card by opening Disk Utility from the Utilities folder, find your SD card on the left and unmount it by pressing the button at the top.
3) Next, you have to format the SD card in terminal. Since I know my SD card is disk one I type: newfs_msdos -F 16 /dev/disk1s1. Yours may differ so really make sure that it is correct.
4) Open Disk Utility again and verify your disk.

For me, this was the only way to actually get this disk to read. For whatever reason, formatting the drive as a fat 16 in Windows 7 did not provide the same results even when I did a format with all 0s.