I removed the 10" to 4.5" reducer flange from the top of the Laser Filter Cavity (LFC) Input Vacuum Cube and placed it on some UHV Foil. I noticed quite a bit of chips from tapping the holes in the vacuum cube that secure the top CF flange. I removed them in 3 steps with the pre-wetted isopropanol wipes: first I removed the chips outside the copper gasket with the gasket in place, then I removed the gasket and wiped the inside ring with a wipe, then I did a final clean of the ring with a third wipe. See the attached photos of the wipes. There was considerable gunk I removed with these wipes that I have never seen before. This could be from the tapping process, but I'm not sure what specifically would cause this. A TiCN coated high speed tool shouldn't do this, nor should the chips generated. A few chips fell into the vacuum chamber but I removed the ones I could see with a fresh wipe.

Once the vacuum chamber was cleaned such that no more residue was picked up by the wipes, I added a new copper gasket (the old one was partially compressed and likely dirty) and a 10" blank flange. I screwed in the 1.75" screws to finger tight on the flange, but they still need to be tightened.