How to choose a Facing Mill or Fly Cutter

[TimGS]

I am new to machining and I would like to purchase a reasonably good but inexpensive facing mill; what do I need to know?

I am looking at an ebay discounttools 3" 5 FLUTE R8 INDEXABLE END MILL CARBIDE FR BRIDGEPORT 90 degree rake; Would this make a good general purpose facing tool...for steel? ....for aluminum?

Would a fly cutter be better for steal? ...for aluminum?

Any advice on Rake angle?

Any other advice?

[BobWarfield]

It's really important to understand your mill size too, BTW.

If you're really going to hog with a face mill, 3" is probably too big even for a Bridgeport and I'd be looking at a 2". OTOH, the widest possible cut will leave a better finish taking light cuts. Most people like seeing "fewer tracks". A fly cutter can be the ultimate for a wider cut without requiring so much cutting force it bogs down a lighter machine. Widgitmaster uses fly cutters to good effect in his work, for example.

Anything you can do by way of cutter geometry to reduce the cutting forces (e.g. positive rakes, and the are rakes in more than one dimension on these cutters) will really help, as will the geometry of the chosen inserts.

One approach is to look at the more expensive face mills, and then go find the knock offs. Which knock offs have similar rakes? Which ones use the same inserts?

Try to avoid proprietary and hard to find inserts. Face mills are expensive to buy inserts for. I have a 2", a 2 1/2", and a 3". The 3" takes 6 inserts. If I blow up all 6, that's not cheap to buy new inserts! When contemplating new indexable tooling (e.g. tooling that takes carbide inserts), I always check whether the inserts are easy to find at places like eBay or Carbide Depot.

Lastly, check out Glacern's face mills. I just got a 3" and love it. Best surface finish I"ve seen yet with the aluminum inserts on aluminum. And they're on sale (I think their sale ends today).

A 45 degree lead angle face mill will generally leave a better surface finish than a 90 degree, all things considered. I use my 2" 90 degree Helimill for hogging and my 3" Glacern 45 degree to make a nice finish.

Cheers,

BW

[TimGS]

Thank You very much for the good advice.

I have a Sieg X2 mill....not a whole lot of power but good enough for now.

[BobWarfield]

Go check out Hoss and see what kind of facemill he runs. He's the man for X2 work!

Cheers,

BW