Our vertical mill CNC project is barely far along enough for us to run a simple G-code program, so there's a lot we don't yet understand about the machine's capabilities. Pieced together from mostly salvaged parts, we don't exactly have a reference manual we can check for the machine.

What's clear from our first test is that it's easy to accidentally get too aggressive with the machine. The most fragile part in the system is our 1/8" RotoZip cutting tool. While we want to make sure to wear eye protection when running the machine, we still want to avoid breaking cutters and turning them into sharp high speed projectiles.

To reduce the odds of that happening, further machine testing will use the largest cutting tool we can. Quarter inch shank diameter is just about the widest we can accommodate with our ER11 collet, so I went looking for the shortest quarter inch square nose endmill I can find on Amazon with Prime delivery. (*) McMaster-Carr has higher quality cutters and a wider selection of endmills in general, but they would not have delivered in time for the next available machine work session so I traded off quality for speed.

This is a carbide tool with two flutes. Out of the box, all cutting surfaces looked satisfactorily sharp. Used properly, it should have no problem cutting into our scrap test pieces of MDF. And when used improperly, it should be far less likely to break than our 1/8" diameter RotoZip cutter. It will serve as the (possibly sacrificial) learning cutter while we explore the rest of our machine, starting with an electrical noise problem.

(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.