I have a 10K as well. I've never gone as big as iwananew10K, but I've been successful using HSS .1 wide cutoff tools in a phase II AXA clone and toolholder. My technique:
1. Make sure the tool geometry is correct and sharp. I use a diamond hand lap after sharpening.
2. Use the minimum stickout possible.
3. Make sure the cutoff tool is absolutely square to the work and centered vertically on the work.
4. Run the lathe on the lowest non-back gear speed.
5. Lock the carriage in place.
6. Tighten the compound gib to lock it.
7. Use plenty of lubricant.
8. Feed firmly. If you can't do the three hand dance of turning the crossfeed steadily and lubricating at the same time, feed in steps.
9. If chips are building up in the cut, pull back immediately and clear the chips.
What he said.
Most folks feed a cutoff tool too slow. Try cutting off one inch brass bar, feeding manually. See how fast you can
run the tool in. In principle that's the feed rate you can use for 1018 but of course it doesn't quite work that way.
Another intesting test is to profile a 3/8 square HSS tool to be a mini-cutoff tool, narrow down the end to be about
3/32 wide and put the correct front and side relief on it. Leave the top dead flat. Make the blade portion only
about 1/4 inch long, and try using that (basically a grooving tool) as though it were a cutoff too. You can feed a
good deal faster with that because the shank and the tool holder is more rigid.
For gummy stuff like 1018 consider the black sulfurized cutting oil.
As for speed, keep increasing the speed until you get chatter. The cutoff tool ideally should be run at the correct
SFPM as any too - what limits this is chatter or another work for 'setup not rigid enough.' If the spindle speed
is too low the part gets snapped off at the very end of the cut, the blade just pushes it off the stock.
Anyone who's ever run a headstock mounted cutoff tool like hardinge makes, understands how important the
rigidity of the setup is. Those things don't even have a leadscrew - they're lever acting. Go as fast as you want.