Everyone hit the nail on the head regarding chatter and size of lathe. Ive been running lathes professionally since '78 working in both tool rooms and screw machine shops, and the most important thing is to use sharp tools, a dull tool with ruin your day. Cutting above center will cause all sorts of trouble without being aware until you get near center and your cutter rides up over the top and breaks. Unless you have to weld your work piece, stay away from C1018 bar because you cannot get a good finish no matter what. I prefer 12L14 screw machine stock and can be bought in small pieces on eBay. Leaded stock cuts much easier than non leaded. If you're machining aluminum, stay with 6061T6, if brass, go with a free machine alloy. High speed tool steel with 8% cobalt will hold up well as long as kept sharp. Most carbides don't work well with carbon steels, except micro-grain types, but carbide takes more pressure to cut and gives poorer finishes. I've done okay by honing a fine edge on carbide inserts using a diamond wheel and lubricant, but only for production runs machining abrasive materials like 11L37 and stressproof. Unless you've got a lot of horsepower and fine power feeds, cut off blades can be difficult to use with out chatter. I'm surprised people are able to turn mild steel in these small lathes, I figured with the low hp, aluminum, brass and plastic are all they will cut. For a few extra bucks, I'd go with a 12" x 24" series lathe minimum. You'll get a good rpm range, enough weight to stay put, and hopefully 220v motor. A nicely tooled lathe of this size will set you back $3,200.
Cris