DIY small countersink for aluminum

Nice work so far! I'm watching this with interest because I too have been stumped at how to cut flutes like a counter sink with a mill/lathe and a bench grinder. In your case perhaps a zero flute countersink might be easier to make?
 
I looked into making a zero flute countersink but was discouraged by the apparent need to perform a "spiral grind" in order to get the desired relief. For instance, see this. Whenever possible I try to avoid making something as a preliminary to making something else. Call it laziness or a runaway git 'er dun attitude, either could be the case :grin big: .

Now, if the spiral-grind fixture could be used for something else useful (sharpening the flutes of end mills? Drills??) I might be motivated to make the thing.
 
Been thinking about the pilot more. If I want to make it with a standard end mill I will need two separate setups on my mill. With the piece held vertically in my RT there is no way to cut the "vee" and leave the pilot fully intact, so I would need to hold the piece horizontally in a vice, then transfer it to the RT and line it up so I can get my 15 degree relief. Doable but a bit of a pain.

However, if I happened to have a Woodruff cutter the right size (I don't) I could probably machine the vee and relief using the RT. Something to think about though.

Even if I give up on the goal of getting exactly 15 degrees, I can't just grip the piece vertically and machine the relief, because it will be about 2 inches above the vice and the diameter of my homebrew CS will only be 3/8 inch. That is a recipe for machining difficulties, to put it mildly. The RT+chuck can accommodate the full length of the piece so I can grip it just below the vee.

I I thought I would be making more of these I would go ahead and make a fixture to facilitate their manufacture, but right now I don't see the need. 99% of the time the holes I want to countersink are accessible with a standard CS.

Pontiac, I've got a question for you. Looking at the photo in message #3, it looks like you cut a relief on both sides of the "vee", but only one of them will actually cut. What is the purpose of the other relief cut?
 
This is all that I am doing with these grinds. I would imagine it is possible on a mill, but it's an easy thing to do with a tool grinder work head.
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