End mill questions ...

[WilleeCue]

Is there any real difference between the 2 flute end mills that Atlas sells and the others costing up to twice as much?

I have used the three flute end mills before and really did not see any reason to pay the extra money for them.
Wouldn't the two flute end mill be stronger than the three flute one?
With the extra cutting edge you get one more cut per rotation.
Does this have the same effect as increasing the spindle RPM by 33%?

 

[Bill the Cat]

End mills

It seems that I read somewhere (I think it was on the Precise Bits web site) that the 2 flute end mills are actually better in the really small sizes that we use for inlays. Working in such tight quarters, the two flute end mills leave more room for the chips to be expelled from the cutting area rather than "gumming up" the cutter.

Assuming the same cutter design, the two flute would be stronger. However, Precise Bits states that their 3 flute is actually stonger than their 2 flute.

It would not be the same effect as a 33% increase in RPM. The CFM (Cutting Feet/Minute) will be the same. However, the Chip Load (amount of material removed/flute/revolution) would be reduced by 33%, assuming that the feed rate and RPM remained the same. In some materials, this could be a bad thing as it would cause burning due to an insufficient chip load.

 

[cueman]

It all depends on what you are milling. Brass seems to like the 4 flutes much better than the 2 flutes. But Ivory seems to like the three flutes. So for all around bits I would say the 3 flutes are probably the best across the board compromise. I am not sure about the speed increase theory, but more cuts normally means smoother cuts which comes from more flutes. But like already mentioned chip removal comes into play also. For drilling holes three flute carbide drill bits out perform two flute carbide drill bits hands down for accurate drilling into wood.

 

[Sheldon]

The precise bits are a superior product, they are more consistent, and stay sharp a lot longer. And Ron Reed is a super good guy, and very helpful. I will support him for as long as I need to buy cutters.