[Alex, Daniel]
I got two aluminum KF50 Centering Rings from Nick Hutzler's group and machined them in the lathe to remove one of their lips so that they can hold a PCB that interfaces with the inside and outside of the Dewer. I clamped them on the outside lip with a 6 jaw chuck. I used a moderate amount of clamping force (~90 degrees of rotation with the chuck key) to hold them. I slowly increased the spindle speed to ensure the rings wouldn't fly off; I used a final spindle speed of 1700 rpm, which is pretty standard for aluminum and a carbide tool. I kept the x-axis of the lathe at around 1.93" and slowly moved the tool in the z-axis to remove the lip. I needed to take off 0.080" of material. For the last few thousands of an inch, I moved the tool in the x-axis instead of the z-axis. I then used a deburring tool by hand to remove any burrs from machining. I could not see any markings from the clamping jaws.
Tomorrow, I will clean and start to bake out these centering rings.
We cleaned the centering rings with the normal aluminum procedure of successive 3 minute baths and scrubs of 1:30 Simple Green:DI water, DI water, and isopropanol. We put it in the vacuum oven to bake out at 120° for 48 hours since we don't know the alloy of aluminum.
I turned off the vacuum pump and closed the valve to the vacuum pump around noon today. According to the vacuum oven, the bakeout lasted 49-50 hours. We can store these parts under vacuum unitl we need them or the vacuum oven.
I machined 3 more aluminum KF50 centering rings exactly like I did the first 2.
We moved the two cleaned centering rings out of the oven and put them in UHV foil and an antistatic bag. We repeated the cleaning process for the three dirty rings and are baking them out.
I turned off the vacuum pump and closed the valve to the vacuum pump