Today was probably the most nervous I've ever been to complete the final operation on the parabolic mirror part.
There are three holes on this piece, one meets down to another side pocket that I milled out on the 4th axis, and the other two break through the bottom of the triangular piece; they are all over five inches long. The sketchy part about this was how long each of the drills had to stick out to remove all the material. One of the drill bits was only gripping about a quarter of an inch in the collet and would ring when I put it in the VF2.
Since each of the tools was so long, I took the advice of my boss and put together some shorter drills to remove about half of the material, allowing the more extended drills not to work as hard. Before coming in with the longer tools, I used a center drill and set the path to prevent any deflection from the first peck.
Thankfully everything went smoothly, and I slowed everything down quite a bit to let everything take its time. This was the only part I had, and I didn't have enough time to make another one if this failed, so everything was slow and steady. After the drilling was finished, I used a tapered threadmill and hand tapped the holes that needed it, then deburred everything and packaged it all up. Definitely a unique part and had its challenges, but I'm delighted with the outcome.