Beginner's question about facing head

[compact8]

The difference in insert height is most likely due to the insert tolerance. A K tolerance is given as a half thou. M tolerance is 2 to 5 thou.
If you are using APMT inserts switch to APKT.

Insert Designation Chart - provides ANSI and ISO designation code definitions for carbide insert shapes, relief angles, tolerances, chipbreaker codes, hole types, size values, thickness values, radius values, wiper lead angle, wiper clearance angle,

Carbide Insert Designation Chart

www.carbidedepot.com

Mine is APKT but they are Chinese made and cost just one buck each so the designation K may not be reflecting the reality.

 

[compact8]

I got a pretty cheap face mill with my RF30 knockoff. I couldn't get a good finish because the pockets weren't machined the same. I took 3 cutters out and left one. A lousy face mill turned out to be a half way decent fly cutter.

I think the pockets being different should not affect the finish but just the distribution of loads to the inserts. In the worst case only one insert is touching the workpiece hence cutting. The mill will become essentially a fly cutter but the finish will not be affected.

With inserts that are said to be great for cutting stainless steel, I got very poor finish on the material because the cutting edges are not sharp enough. They are designed to take deeper cut and more powerful machines are required. Then I switched to periphery ground inserts designed for aluminium. The result is great because the cutting edges are very sharp ( no honing or land ). Tool life is expected to be short though.