When I first started working with my CNC Router, I mostly gathered upcut end mills, as they seemed to my mind to be the best choice for most jobs: leaving a nice clean bottom to the cut, which seemed to me to be the most important. What I didn't realize is their propensity to leave a bit of a ragged edge at the top of the cut, particularly in challenging materials like certain plywoods or soft woods such as pine or fir. Of course, downcuts have a great place in a CNC-ers tool arsenal, but I'm really starting to appreciate what a downcut bit brings to the table after I obtained this 1/8" downcut end mill.
To illustrate the point, I found a stash of old Luane plywood in my workshop that I saved from a prior build, and cut it up into small pieces to use for experimentation and learning purposes with my CNC. This plywood even when new was terribly prone to splintering, and it hasn't gotten any better with age. So some of my test cuts end up looking terrible, especially when using an upcut bit. But it was a terrific testing platform for this new downcut bit. And as the brief video I attached to this review shows, despite this challenging wood the cut I did as a demo had very clean top edges. I used a profiling toolpath which simply follows the contour of the characters being cut. With the font I selected having both inner and outer vectors for each character, the cut followed the two vectors, leaving some uncut material between them, so it looks a little weird. But the top edges of the cut paths are quite clean and smooth. At the end of the video clip I contrast the cut to a prior cut I made in another piece of the Luane using an upcut bit - where the top edge of the cut is tattered and splintered.
This bit is a high quality tool - 100% solid carbide and with a low-friction coating to help extend the life and sharpness of the bit, as well as provide smoother cutting and cooler running. It has an extra-long overall length and cutting portion providing great reach for deeper cuts. This is a very good and clean-cutting bit. I use it for a CNC machine, but it's also great for handheld plunge routers or for use in a router table.
