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Winston

wrote:

I have an aluminum tube that I need to bore about 1" at end out to at
least 5.57" -- it varies from about 5.47" to about 5.60".

What diameter is the tube, now?
I remember reading in TMBR about a technique that was very cool if you can
figure out how to clamp one end of the tube to a non-moving bench.

1) You find or make a cylindrical plug that just fits inside the present bore.
2) Drill through the axial center of the plug and tap for a (say) 1/2"
machine screw (with backup nut).
3) Mill radially into the top of the plug to accomodate a lathe tool and
space to hold some swarf.
4) Drill into the plug to accomodate a clamping screw for the lathe tool.
5) Clamp the lathe tool in the plug, thread the 1/2" machine screw with a
backup nut and lubricate the OD of the plug.
6) Insert and rotate the plug in your tube. The body of the plug will guide
the cutter and keep it at a constant depth of cut.
7) Use a breaker bar to create your new bore.
8) BE the mill.

--Winston