indexable face mill setup

[fjbart70]

I have a 2.5" 4 insert face mill 90 degrees.

I have been setting my TLO based on the lowest insert. The inserts vary in height by a few thousandths.

Is this OK or does each insert need to be exactly the same?

If so how do you go about setting them all the same?

[fizzissist]

If your inserts vary by a "few thousandths" each.....you're doing something wrong or you have the cheapest face mill on the planet.

1. How do you know they're off by that amount without measuring? ..and 2. Putting an indicator facing up on the table and slowly turning the spindle by hand and sweeping the cutting edges over the indicator will tell you exactly how different they are.

The better inserts have their corners numbered, or indexed, using either numbers or bumps. Always load the mill with the inserts oriented so the same reference is cutting. That will minimize differences and give a better finish.

But a few thousandths????? You're using a VERY expensive and time consuming face mill that's adjustable, or the cheapest face mill you can buy.

[RICHARD ZASTROW]

If the facemill is not designed to have different heights for alternating inserts, they should all be the same height. There are "step mills" out there. Some had some inserts cutting at a slightly larger diameter as well.

Cutter manufacturers try to have them accurately at the same diameter and cutting height.

If they aren't at the same height, the chip load is not shared equally. One extended insert will act as a fly cutter. This will produce a coarse finish.

There is an exception, the cutter could have a position for a "wiper" insert. This uses a wiper insert to burnish the surface.

Dick Z

[christinandavid]

Obviously you've checked that every part of the assembly/arbor/taper is clean and runs flat/true?

If it all looks good, and you need to use that particular tool and get a decent surface finish, remove the offending inserts I often resort to a single insert on the big old knackers I have to use...

DP