All Metal Valve Maintenance
Maintenance instructions for all metal valves. Manual below:
Varian - AllMetalValves.pdf
Disassembly
Dissassebly should only be performed in one of the following states:
Both sides of AMV under vacuum, AMV closed.
Both sides of AMV at 1 atmosphere, AMV open or closed (preferably closed).
Procedure:
Use the Torx-like AMV tool (similar to a 3/32" allen) to unscrew the inner screw (inside the retractor screw) several turns (no need to remove completely). It is a standard right-handed screw.
Use a 1/4" allen to unscrew the retractor screw completely. It is a standard right-handed screw.
Unscrew the drive screw completely.
Lubrication
RTFM in the share. Basically, clean off old excess lubrication with fine wire brush and possibly a clean wipe or two. Get rid of any chunks and particles. Use a 1/8" wide piece of metal or plastic (just fold some UHV foil over several times) to apply a bead of lubricant to one part of the bottom threads of the drive screw (no need to spread all around - that will happen when screwing it in). Do the same for the bottom threads (farthest in) on the inside of the bonnet (this is pivotal) . Also lubricate the 3/32" inner screw threads, but NOT the 1/4" retractor screw threads. Finally apply generous (but not excessive) lubrication to both washers.
Reassembly
First of all, RTFM (Read the ****ing manual). Second of all, don't trust the manual because it is written for an older model with a left-handed "retractor nut". Our model has a right-handed 1/4" allen socket screw. However, as shown in the pictures in the manual, the bolt has a smaller 3/32" allen screw inside of it which expands the end of the retractor screw. This is used to fix the retractor screw in place inside of the bellows' female screw socket. When installed correctly, turning the drive screw (the large screw that is used in standard operation) will not cause the retractor screw to turn. The easiest way to achieve a correct install is the following:
After cleaning and lubricating the bottom drive screw threads, the two washers, and the bottom threads inside of the bonnet, start with the 3/32" allen screw (the one inside the retractor screw) unscrewed to the point of being flush with the bottom of the 1/4" allen socket.
Before installing the drive screw, assemble the drive screw, retractor screw, and two washers as a unit. Now, use a 1/4" allen to hold the retractor screw in place while screwing in the drive screw (This will prevent the inner washer from falling out of place while screwing in the drive screw).
Tighten the drive screw down to the desired torque (the retractor screw should still be loose).
Begin tightening the retractor screw down. If it feels like the threads are slipping, pull it out and screw in the inner (3/32" allen) screw so as to expand the tip of the retractor screw, then try again. Don't over tighten the retractor screw. Only a foot-pound or so of torque is desired. Too much torque will cause the retractor screw to rotate with the drive screw.
Now that the retractor screw is tightened down, screw in the inner 3/32" allen screw as tight as is reasonably possible.
Open the all metal valve a turn or two.
If the retractor screw is loose at all, repeat the last three steps as necessary.