The first week in July I fabbed struts in the MechE shop for our cryostat to follow option 2.2 in the previous entry. I requested a quote from Millitnow to fab a new blank for the top plate. However it sounds like they don't do lathe work, which means they cannot make this part--as far as I understand, o-ring grooves can't be milled because that will introduce radial machine marks that will limit our vacuum.

I might be able to machine this part myself, but I'm not super confident that I'd be able to machine the groove to spec (though could be fun, if it's worth it I'll just spend the day on it)... does anyone have tips on where to go on campus for this--is GALCIT the way to go? Alternatively, maybe Millitnow can make the part and we just polish it to remove radial grooves--is this standard practice anyway? What do people really mean when they say "no radial grooves?"

Any advice on this appreciated. I've attached the drawing and sldprt for reference.