Upcut vs downcut tooling

[Papajohn7 (John Eustace)]

Is there an easy way to recognize an upcut or downcut endmill?
TIA for your replies

[ScottsdaleSteve (Steve)]

Here’s a pic of the flute direction on up vs. down bits/endmills:

Also discussed in this thread:

Upcut vs. Downcut

How can you tell if a bit is Up Cut vs. Down Cut? I never paid much attention to my bits before. If they were up cut or down cut I cut a lot of my designs on PVC. When using a 1/4 or 1/8 inch bit the cut areas clear out pretty well. But when i use a 1/16 bit the cut area seems to clog up with the cuttings and i have to dig it out. Guess its time to check my bits and see if they are up or down cut Anyone have any experience with this.

[gdon_2003 (Guy Donham)]

Routers all turn in the same direction. In the picture above from @ScottsdaleSteve the bits would turn from left to right. The upcut would pull the chips out and the down cut would push the chips down.

Some spindles can turn backward but that is rare but would reverse the function of the bits. Not sure the bits would be very efficient because they do have a cutting edge that is biting into the wood so if it ran in reverse the leading edge would not be there to bit the wood.