This is a newbe question

I'm working in aluminium, the origional plans I'm following had a lot of work done on a Lathe
I'm attempting to do it with a mill on a rotary table (don't presently have a lathe)
(Nothing spins so perfectly round/ concentric is not a big issue)

I need to cut a chamber behind a 1" threaded opening.

The chamber is round about 1.75" in diameter and .375 deep.

The instructions i'm following said to use a dogleg tool on the lathe.

since i'm trying to do this on the mill its a bit different.


So several questions....

1)If I go borrow a friends lathe, where can I get/ how do I make a dogleg tool?
I just know this is going to be answered something like
"make a steel tool and grind the proper relief, rake and chip clearance..."
Where can someone learn what all the bit/tool grinding names mean, releif, rake etc....


2)What tool would you use on a mill to do the same job
What tool would you buy or how would you make it?

I've been thinking that something like a tslot cutter would be the proper tool.
Alas finding one with a 1/4" shank and 1" cutter head may be tough.


My other option is to just machine it out to 1.75 then weld a plate/ plug in the top of the hole,
and machine the hole back out to 1" and thread it.


Paul