1. Find the drive
sudo apt-get install ufiformat
sudo ufiformat --inquire --verbose

… Floppy drive was /dev/sdb
list usb fdd devices
disk         generic     
/dev/sdb     /dev/sg3    

2. Image to the floppy
sudo dd if=floppy-grub4dos of=/dev/sdb

To mount floppy drive
sudo mount /dev/sdb /media/floppy