No. Exactly the opposite. Set the tool as if you're going to take a turning cut, so you move towards B, not A. The 10° angle I spoke of would be such that the tip of the tool is closest to the face, while the heel of the tool is a small distance farther out. Experiement a little. You may find that 5° is better. That way as you face out the tool will remove material away from the tip, leaving the tip to bring the part to length. That helps limit the effect of the interrupted cut as the tool will always have a complete cut along the edge. That minimizes the hammering that is so destructive of carbide.
Hopefully you now understand that you had the wrong impression. If the angle of the tool is shallow enough, perhaps you can see how you can actually start the cut at a point on the tool that is near to you. As you face out, the tool cuts deeper due to the angle.Should I be trying to touch the tip (X) to the splined area to cut or somewhere closer to the middle of the cutting edge (Z)? I'm assuming the tip?
It's hard for me to know exactly what speed might be beneficial, but I strongly recommend you stay away from 500 rpm on something this hard. As the hardness increases, the resistance to cutting produces a corresponding increase in heat, which is amplified by speed. The best indicator is the chip that comes off. It will be discolored, of that there is no doubt, but if it's coming off red, that's too fast for carbide, which will experience failure. Unlike many lathe operations, where increasing speed often pays dividends, slowing down when machining hardened objects, as well as the 300 series of stainless (excepting the free machining alloys) is generally beneficial.Should I try to increase the RPM at all from 150? Is that too slow? Torch had suggested 500RPM.
I don't think so, not with the equipment you have at your disposal. Procedure is likely more important than tool type. The only change I'd make in your situation would be to use an insert that offered greater strength-- a parallelogram instead of a triangle, but you can accomplish the task adequately with what you're using, in spite of some saying you need to use a parting wheel. It's not that I don't think that will work, as it will, but if you want to do the job with carbide, you just have to approach the project differently. When you take the cut as I suggested, the bulk of the material is removed away from the tip of the tool, so it remains sharp longer. It takes advantage of the portion of the tool that will never, otherwise, see a cut. Why not use it?Is there a better cutting tool/implement I should use here than these carbide indexed inserts?
Many, many years ago I was tasked with creating a rather large and coarse thread gauge. I had a virtually new Monarch EE at my disposal, which was used to make the needed gauge. The thread was roughed (I recall using Graphmo toolsteel), then the piece was heat treated with a target hardness of 62Rc. We did not have a thread grinder, so finish cuts were taken with the Monarch, using carbide. I found that I could take very thin cuts (a thou per pass) at an exceedingly low speed, perhaps 15 rpm. In backgear that was possible, as it had infinite speed control. The end result was satisfactory, although it would not compete with a ground thread.
I make mention of this as an example of what can be done.
One more thing. I made mention of the use of either C5 or C6 carbide. For roughing that is important, but if you get down to a tiny finish cut, you may be pleasantly surprised by the results you'd achieve with a C2 grade. It's harder than the other two but doesn't resist shock as well. I suspect that used with the angle I suggested, it may just do the job quite nicely. Worth a try if you happen to have one of the inserts.
H