I just finished making my vacuum system. I didn't buy anything other than fittings, bearings and the pump. I made my own Rotary Adapter out of maple.
I have a Oil Bath Robinair 5 cfm pump. It pulls 29"hg.
I hooked up all my hoses and valves and my spindle adapter. I closed the valve to the rotary adapter. It showed 29"hg. I opened the valve and put my thumb over the end of the lamp rod. I only could get 21"hg.
I fooled with it and determined it was leaking through the bearings. I have two bearings with rubber seals on both sides. I put saran wrap over the bearing and it sucked it down and the pull went up to 26"hg or so.
What can I do about this?
It is not leaking around the bearing, it is coming through the bearing.
RP