Hi,
I just ran a test with a .016 end mill in the Rhino 3 version and did not have this problem. Could you post a screenshot of your tool settings or better yet, the .3dm file. If your tool length is shorter than what it needs to do it won't work (kind af a failsafe reminder).
3dm is attached. I have gotten this error with other designs, so it's not a problem with the model. I get the error in cutter selection, not when I try to generate a tool path.
I probably wasnt real clear. When I goto cutter selection, I try to define a .016 diameter cutter, and I get a pop up error saying "cutter diameter too small". I played with different lengths (both of them), different tolerances, etc and still got the error.
If I entered a stock to leave number of greater than .002", it also worked with the .016 diameter.
All the entities that I am cutting are flat.
I did some experimenting, and I can get down to .02" diameter and it'll accept it. .019 and I get the error.
OK, this one is for higher authorities. Like I said, I don't get this error on my my setup but when selecting a small cutter in your file I get the same error message you got. I am at a loss.
Dave
I would put money on the latest Madcam build fixing your problem.
I imported your drawing into a fresh Rhino template and to small cutter error message is gone.