Trying to compensate for tool deflection is a very large variable, influenced by;
(1) Weight/rigidity/design of the machine itself.
(2) Type of cutting tool, roughing mill cutter/finish mill cutter type.
(3) Sharpness of the cutting tool.
(4) Cutter design, cutters for aluminum have more chip clearance than general cutters.
(5) Type and alloy being cut; aluminum, mild steel, tool steel, high-carbon, stainless etc.
(6) Material hardness.
(7) Speed the cutter is being pushed through the work.
(
Depth of cut.
(9) Direction of cut; climb cutting v.s. conventional cutting.
(10) Type of coolant, if any?
(11) Solid carbide tool v.s. High speed steel cutter.
(12) Length v.s. diameter of cutter.
(13) Spindle precision.
(14) Tool holder/collett quality.
and, probably a few more I have not thought of here.
Climb cutting gives a better finish, but must be used carefully, as machne backlash may allow the table to let the tool dig in unexpectedly.
For consistent production type machining, use a roughing cutter leaving the part oversize (approx .010/.015") and finish off with a finish style cutter
using a climb cut. This will permit the lightest possible tool load for the finish dimension, and the variation of the roughing deflection will not enter into
finish dimension equation.
Also, the finish cutter will see less material to (less cubic inches of material to plow through) to dull it's new sharpness.
If the finish cutter is a high quality carbide, it will be even better, as carbide will retain it's edge longer than H.S.S.
All tools deflect to some degree or another. It depends on how close and how smooth your finished part has to be. It is all a trade-off, and how much
time and money can be expended per part.
Regards,
John