Lathe advice

[velocity3x]

I thought it was really bad to have it above the centre line? You either have it on centre or very slightly below it?

Tool height should be set on center line. If it is set below and you're parting small diameter stock, the work piece can / will climb up onto the tool and ruin everything.

[Technician1002]

What spindle speed are you using? Actually, it should only take a few seconds. Personally, I'd part 10mm mild steel about 600 rpm's with a generous supply of oil from a brush.
Also check the parting tool height.

Instead of simply depending on an RPM, look up the recommended cutting speed of the material you are cutting. It is listed in feet per minute. Larger diameter work will require a lower spindle speed for the same surface cutting velocity. Do not exceed the recommended cutting speed to prevent damage to your tools.

http://its.fvtc.edu/machshop3/speedcalc/speedrpm.htm