What’s the Difference Between an “O” Flute and a “V” Flute Router Bit?

The letter designation “O” or “V” refers to the geometry of the flute, area behind the cutting edge, of the router bit. A “V” flute has a 90˚ angle behind the cutting edge. While an “O” flute has a very curved flute. The next question, “which geometry is better?” depends entirely upon what you are cutting. The general rule, is that you want to use the geometry that works with your material.

Some materials create chips that curl away. While others create chips that chunk out in tiny little blocks. Use a geometry of bit that has a shape to support the natural behavior of the material you’re routing. Soft plastics, like sintra, tend to curl and create chips that look much like grains of rice. For sintra I would recommend using an “o” flute. Whereas a hard plastic, like acrylic, has chips that come out looking a lot more like sugar crystals. A “V” flute could work well here. Although, I will point out that some of the more popular acrylic cutting bits are “O” flutes.

These are not hard and fast rules. But, they are meant to help you start thinking about what kind of bits to use for certain jobs. There may be a time where you specifically want to deter a material from its natural tendency to create long curls. For example, redwood often creates very long curls as you route it, but these long curls can cause issues for the machine, in addition to blowing out the top edge. A good solution for this issue is to use a “V” flute bit, which will break the long chips into smaller pieces.

When you keep a journal of what parameters you used to route certain jobs you can start to notice patterns, and then tweak various levers to get different results. As always, if you ever get stuck and aren’t sure which lever to tweak next, please give us a call and we’ll work through the problem together.