If you were trying to part off steel, I'd tell you store that HSS tool in the round file
But for aluminum, you should be able to make it work. I'd try grinding about a 1/4 to 1/2" radius in the top of the blade, attempting to create a "hollow ground" hook. For aluminum, this top rake "hook" can be very positive, because the heat is not going to hurt the tool, and positive rakes cut more easily.
The tool tip needs to be on center height.
Watch closely the front clearance that you give to the blade. It only needs 2 or 3 degrees of clearance, because in lathe work, the roundness of the work itself creates adequate clearance. Too much front clearance will contribute greatly to the chatter. With reduced front clearance, the front of the tool helps stabilize the workpiece, and dampen vibration.
If you have constant surface speed available on your cnc, this is a good time to make use of it. You can use all the rpm that you dare, but you must keep the feed up at a steady, aggressive pace.
Use flood coolant if possible. Plan to retract a couple of times to apply lube manually, if that is your method.
At 1100 rpm, your feedrate should be about .002 to .004 per revolution. If the lathe cannot handle that, then maybe try a 3/32" wide blade.
There is an advantage to using commercially made part off tooling with carbide inserts. These inserts have chip formers on top that will help the chip roll up in a coil, and at the same time, they also narrow the width of the chip so that it comes more easily out of the groove.
One guy I used to know, used big old power hacksaw blades as "tool blanks" for parting off. These are quite narrow, and don't take too much power. He also ground a pronounced hook in the top of the blade to improve the cutting action.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)