Correct tool height when using Armstrong tool holders

I'd like to pick some brains regarding the proper setup and use of Armstrong style tool holders. These holders incline 20 degrees upwards into the workpiece. This makes tool grinding a bit easier, but I have to wonder if it might contribute to tool chatter if the tip of the cutter is set at the workpiece's horizontal centerline. As the tool bites into the work and down forces are applied to the bit, the 20* incline will tend to flex into the work, will it not?

From this, is it best practice to tilt the rocker base such that the tool bit contacts the workpiece lower, closer to it's 20* arc-tangent until a facing operation is called for? Or does the general rule of setting the tool at the work's horizontal centerline still hold?

Given I have 1" between the top surface of the rocker and my lathe's centers, would it be more ideal to use a 1/2" square bit stacked on top of a 1/2" square spacer for heavier roughing operations? A bigger tool would have the advantage of better heat-sinking and increased rigidity, would it not?

Good to pick up the book How To Run A Lathe.

A lot of good advice there, Very often one will set the bit a tad above the centerline for turning mild stock and at centerline for facing, and one might grind the bit Flat Top turning brass.

Chatter comes from many problems.

I have stacked my tool holder higher as you mentioned, and that for using a parting tool.

Yes, a bigger, biggest tool bit would do that for heat but the tool bit size is for economy and designed suitable for the actual size and strength of the machine.

A 1/2 " bit used on a hobby small lathe would cause more problems than it's worth.

Armstrong tool holders are designed to not use the rocker. They are supposed to be flat down on the washer and you set the tool height in the holder. I always set mine with the tool on center and I never have problems.