If you are refering to the 7x10 or 7x12 mini lathe, a butt will not fit through the spindle, which is only .750 id. Also note that the spindle and chuck back plate are one piece, and without the chuck, the spindle has a #2 morse taper, which has a maximum id of about .700. This means that you cannot even work on the joint end of a shaft in this machine. However, it is a good machine for ferrules, tips, and with the addition of a means to provide a tailstock, shaft cleaning and sanding are possible. There are several hobbyist sites devoted to this machine and its variations. Just search "mini lathe", and you will find complete specs, and many clever modifications that people have made to suit a wide variety of needs.
Correction to the above: The mini lathe has a #3 morse taper in the spindle, but it is the thru-hole in the chuck that limits diameter to less than .700.