Confusion on single flute bits

I am about to try my luck milling a brass branding iron with c360 brass. I have watched all the @wmoy videos on brass and I am confused on a particular statement he made. One video is dedicated to the use of single flutes for metals and the advantages they provide in metal. Then on one of his office hours video where he re-creates the carbide logo branding iron he mentions that O-flutes for plastics are not the best for metals. My confusion is that I thought O-flutes and single flutes are the same. If not what is the difference? I have several Amana spektra O-flutes and was going to use them for this project but now I am hesitant. Can someone clear this up? I don’t want to ruin or break them as they are a bit pricey.

My understanding is the O-flutes are single flute bits which have an especially deep flute which provides excellent chip evacuation, but which is so deep it weakens the endmill making it only suited to use in softer materials such as the plastics they are designed to be used in.


I see. I have your 274-z endmill. I will use that. I also plan on using your 60 degree vbit to finish out the detail on the lettering. Any suggestions on F&S for it?

Having done a few brass things now I usually reduce aluminum down a bit. Both speed and depth of cut and I think I run it a bit slower in carbide motion.
I think Winston mentioned about 80% of what aluminum is in one of the live streams?

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“O-Flutes” are single flutes, but not all single flutes are designed the same. Plastic-specific endmills have extra sharp (but weaker) cutting edges to slice through plastic, but they will not hold up to being thrown at aluminum. A general purpose, or aluminum specific single flute will work in plastic just fine though. The surface finish just might not be nearly as good.


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